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					       Oregon
        Theodore R. Kulongoski, Governor
                                                                     Department of Transportation
                                                                               Geo-Environmental Section
                                                                                  Transportation Building
                                                                              355 Capitol St. NE, Rm. 301
                                                                                  Salem, OR 97301-3871
                                                                                                        5
                                                                                FILE CODE:

Date:             October 22, 2008


Subject:           Stormwater Treatment Best Management Practices (BMP) Summary
                   Reports

Introduction
The Stormwater Treatment Best Management Practices (BMP) Summary Reports provide
information on the water quality BMPs included in Chapter 14 – Water Quality of the ODOT
Hydraulics Manual. The BMP Summary Reports provide the ―back-up‖ information to support
the Water Quality BMP Selection Tool (BMP Selection Tool) developed by ODOT and the
natural resource agencies as part of the Stormwater Management Initiative. This memorandum
briefly describes the BMP Selection Tool approach and includes the summary reports for
individual BMPs. The BMP Summary Reports for use with the BMP Selection Tool will be
included in the ODOT Water Resources Manual (in development).

The focus of the BMP Summary Reports is to provide information on: (1) BMP effectiveness
and (2) selection criteria for each of the BMPs included in the appendices to Chapter 14 of the
ODOT Hydraulics Manual. Information on basic descriptions and application are taken directly
from the draft appendices to Chapter 14 for consistency.

Outline BMP Selection Tool
The BMP Selection Tool is intended to provide consistent guidance and informed decision-
making for water quality specialists and hydraulic engineers in selecting best management
practices to meet stormwater management objectives for ODOT projects. The selection process
is not expected to identify a unique BMP or treatment train, due to the qualitative and subjective
nature of some of the factors to consider in selecting a BMP. A separate memorandum describes
the BMP Selection Tool and process in more detail, Stormwater Treatment Program - BMP
Selection Tool (April 9, 2008). The description below is for context only.

The BMP Selection Tool is based on the information presented in the key references reviewed as
part of the project. The primary references used in developing the BMP Summary Reports and
modeling the BMP Selection Tool are listed at the end of this memorandum. Conceptually, the
BMP Summary Reports provide information on the following issues consistent with the
requirements of the BMP Selection Tool:

        Stormwater treatment suitability factors
            o Can the BMP meet the stormwater rate, volume, and water quality treatment
              requirements mandated by local regulations at the site or are a combination of
              BMPs needed?
          o Determine the management objectives: recharge, water quality, channel
             protection, peak discharge, and stormwater hotspots.
      Physical feasibility factors
          o Are there any physical constraints at the project site that may restrict or preclude
             the use of a particular BMP?
          o Factors include: surface area, drainage area, soil permeability, groundwater levels,
             and slope.
      Other non-design factors
          o Do the remaining BMPs have any important community or environmental
             benefits or drawbacks that might influence the selection process?
          o Factors include: maintenance, acceptance, construction cost, habitat quality,
             nuisances.

Contents of BMP Summary Reports
Five classes of BMPs were defined to be consistent with the BMP Selection Tool process.
Summary reports have been prepared for the following BMP classes:

      Pretreatment class: oil control facilities, sediment control facilities
      Infiltration class: infiltration pond, bioretention, bioslope, porous pavement
      Filtration class: grass swale, filter strip (with and without soil amendments)
      Pool-ponds class: Constructed wetlands, extended dry detention ponds, wet ponds
      Space-constrained or Urban application class: wet vaults, media filters, proprietary
       separation, proprietary filtration

The final format and content BMP Summary Reports will be finalized as part of the development
of the ODOT Water Resources Manual. Each BMP Summary Report includes the following
sections:

      Description
      Application
      Pollutant Removal Mechanism
      Targeted Pollutants
      Schematic
      Series of tables with qualitative ratings for BMP applicability and effectiveness intended
       to correspond with BMP Selection Tool components:
           o No. 1 Stormwater treatment suitability – evaluation against different stormwater
               management objectives in addition to water quality benefits (e.g., recharge or
               channel protection).
           o No.2 Receiving water type – the type of receiving water strongly influences the
               preferred BMP to use (e.g., increased treatment requirements may required or
               certain BMP types may be discouraged because of temperature impacts to
               sensitive water bodies).
           o No. 3 Water quality parameters – effectiveness of BMP in treating stormwater for
               certain pollutant types of categories.




                                                                                                2
o No. 4 Physical site suitability – considers site conditions to identify appropriate
  BMPs.
o No. 5 Non-design factors – accounts for maintenance, costs, and habitat benefits.
o No.6 Treatment train considerations – considers options for using multiple BMPs
  to take advantage of additive benefits.




                                                                                    3
References
American Society of Civil Engineers/Environmental and Waters Research Institute
      (ASCE/EWRI). 2001. Guide for BMP Selection in Urban Developed Areas.
California Department of Transportation (Caltrans). 2005. Stormwater Quality Handbooks:
       Project Planning and Design Guide.
City of Portland. 2004. Portland Stormwater Management Manual.
City of Portland, 2006. Effectiveness evaluation of best management practices for stormwater
        management in Portland, Oregon.
Minnesota Pollution Control Agency. 2005. The Minnesota Stormwater Manual.
National Cooperative Highway research Program (NCHRP). 2006. Evaluation of Best
       Management Practices and Low Impact Development for Highway Runoff Control..
Oregon Department of Transportation. Hydraulics Manual (in-progress).
Shoemaker, Leslie; Lahlou, Mohammed; Doll, Amy and Patricia Cazenas, 2000, Stormwater
      Best Management Practices in an Ultra-Urban Setting: Selection and Monitoring. U.S.
      Department of Transportation, Federal Highway Administration Publication No. FHWA-
      EP-00-002, Office of Natural Environment, Federal Highway Administration,
      Washington, D.C. 287p.
Washington Department of Ecology (WSDOE). 2001. Stormwater Management Manual for
      Western Washington.
WSDOE. 2006. Washington State Department of Ecology, Evaluation of Emerging Stormwater
    Treatment Technologies
Water Environment Research Foundation (WERF). International Stormwater BMP Database.
       (www.bmpdatabase.org).
Washington State Department of Transportation (WSDOT). 2006. Highway Runoff Manual.




                                                                                               4
     Attachment

BMP Summary Reports

  A – Pretreatment – Oil Control Facility
  B – Pretreatment - Sediment Control
  C – Infiltration Pond
  D – Bioslope
  E – Porous Pavement (not stand alone)
  F – Grass Swale
       Soil Amendment
       No Soil Amendment
  G – Filter Strip
       Soil Amendment
       No Soil Amendment
  H – Constructed Wetland
  I – Extended Detention Dry Pond
  J – Wet Pond
  K – Wet Vault
  L – Media Filter (non-proprietary)
  M – Proprietary Facility
       Filtration
       Separation
  N – Soil Amendments




                                            5
Pretreatment – Oil Control Facility
Description
Oil/water separators are used generally as a pretreatment device to prevent oil from impairing the
function of a downstream BMP. Oil control facilities are used to remove free, dispersed and
sorbed oil. Oil/water separators are most effective in situations where relatively high
concentrations of oil and grease occur in storm runoff such as in parking lot runoff, high traffic
areas and spill response activities. Separators do not function well at low concentrations of oil.
The two main types of oil/water separators (baffle-type and coalescing) are described here.
Oil/grit separators are also briefly discussed.

      Baffle-type oil/water separators use vaults that have multiple compartments (bays)
       separated by baffles extending down from the top of the vault. The baffles prevent
       floating oil from flowing out of the separator. Oil that collects at the surface is typically
       removed by floating skimmers. Baffles are also installed at the bottom of the vault to
       trap oily, settled material that accumulates.
      Coalescing plate oil/water separators consist of a series of inclined plates (plate pack)
       installed in the oil separation bay of the separator. As oily stormwater flows horizontally
       through a coalescing plate separator, it encounters the plate pack, accumulates on the
       surface, and migrates along the surface of the plate. This coalescing of small oil droplets
       into larger ones increases treatment effectiveness; thus, vault size is smaller than that of a
       baffle-type separator.
      Oil/grit separators uses a long, rectangular vault separated into three compartments. The
       first compartment traps debris, such as leaves and litter, and coarse sediment such as
       sand. The second compartment traps oil that floats to the surface. Oil will remain in this
       compartment until adsorbed by sediment particles that ultimately settle out. The third
       compartment houses the outlet pipe.

Application
   Potential ODOT applications include vehicle storage and maintenance yards, fueling
      areas, and high-use parking and rest areas—areas with high concentration of oil in runoff.
   Use only impervious conveyances for oil contaminated stormwater.
   Usually as the initial part of a treatment train. Best suited for an off-line configuration
      where only a portion of the first flush is treated by the unit and clean out occurs after
      every major storm event.
   Oil/water separators cannot be applied for removal of dissolved or emulsified oils such as
      coolants and soluble lubricants.
   Do not use separators in situations where detergents are used to cleanse paved areas; such
      cleansers chemically stabilize oil, preventing flotation.

Pollutant Removal Mechanism
    Density Separation (key treatment mechanism)
    Sorption
    Filtration




                                                                                                    1
Primary Targeted Pollutants
    Oil and Grease

Secondary Targeted Pollutants
    Sediment/Particulate
    Metals (particulate)




                                2
Schematic Detail




                   Baffle Type Oil/Water Separator




                                                     3
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  Low                Considered a pre-treatment device and designed to
                                                   provide removal of oils and grease (and some
                                                   sediment) only.
 Channel Protection             N/A                Considered a pre-treatment device and provides
                                                   minimal channel protection.
 Peak Discharge                 N/A                Considered a pre-treatment device and provides
                                                   minimal peak discharge reduction.
 Recharge                       N/A                Designed for separation of oils and grease and to not
                                                   allow infiltration.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**     Comments
 Drinking Water Protection(1) Restricted           Considered a pre-treatment device. Must combine
                                                   with other treatments
 Aquatic Species               Restricted          Considered a pre-treatment device. Must combine
 Protection(2)                                     with other treatments
 Water Quality Protection(3)   Restricted          For oil and grease removal only. Considered a pre-
                                                   treatment device. Must combine with other treatments
 Wetlands Protection(4)        Restricted          Considered a pre-treatment device. Must combine
                                                   with other treatments
 Sensitive Lakes               Restricted          Considered a pre-treatment device. Must combine
 Protection(5)                                     with other treatments
*Category Notes:
(1)
    Drinking water Protection – Use the sensitive lakes category to define BMP design restrictions for surface water drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                                  4
Note: Oil Control Facility is considered a pretreatment BMP. An “Overall Effectiveness Rating” is provided
below; however, removal efficiencies and effluent concentration are not documented. Pretreatment BMPs
are selected on a prescriptive basis and water quality treatment levels should be based on the primary
treatment BMP selected in the treatment train. See also Tool Component No. 6.
  Tool Component No. 3: Water Quality – Effectiveness
      Parameter          Overall        Documented Removal            Statistical Difference
                      Effectiveness      Efficiency and Effluent   Between Influent-Effluent
                         Rating(1)           Concentrations             Concentrations
  Sediment/          Moderate          Removal Efficiency:       Average influent-effluent:
  Particulate        (oil/water)       NA                        NA
  (Total suspended Moderate            Effluent Conc.:           Influent-effluent EMCs:
  solids)            (oil/grit)        NA                        NA
 Nutrients:             Not                Removal Efficiency:           Average influent-effluent:
 (Nitrogen,             applicable         TN: NA                        TP: NA
 Phosphorus)                               TP: NA                        TN: NA
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           TP: NA                       TP: NA
                                                                        TN: NA
 Hydrocarbons           High               Removal Efficiency:          Average influent-effluent:
 (oil and grease)       (oil/water)        NA                           NA
                        Moderate           Effluent Conc.:              Influent-effluent EMCs:
                        (oil/grit)         NA                           NA
 Bacteria               Not                Removal Efficiency:          Average influent-effluent:
 (pathogens/E.          applicable         NA                           NA
 Coli)                                     Effluent Conc.:              Influent-effluent EMCs:
                                           NA                           NA
 Metals                 Moderate           Removal Efficiency:          Average influent-effluent:
 (particulate and       (particulate)      NA                           Cu (total): NA
 dissolved)                                                             Cu (dissolved): NA
                        Not                                             Zn (total): NA
                        Applicable                                      Zn (dissolved): NA
                        (dissolved)        Effluent Conc. (ug/L):       Influent-effluent EMCs:
                                           Cu (total): NA               Cu (total): NA
                                           Cu (dissolved): NA           Cu (dissolved): NA
                                           Zn (total): NA               Zn (total): NA
                                           Zn (dissolved): NA           Zn (dissolved): NA

 Polycyclic             Not
 Aromatic               applicable
 Hydrocarbons
 (PAH)

Notes:
Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                   5
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Small                 Considered a pre-treatment device only. Less 1 percent
                                                 of drainage area. Negligible except for access.
 Drainage Area(2)          Small                 Considered a pre-treatment device only. Typically less
                                                 than 1 acre.
 Soil Infiltration Rate(3) Not Applicable Soil infiltration rate is not a critical factor for siting the
                           +                     facility
 Slope (gradient)(4)       Not applicable Slope is not a critical factor for siting the facility.
                           +
 Groundwater level(5)      Not applicable Depth to groundwater is not a critical factor for siting
                           +                     the facility
 Dependency on Soil        Independent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Small <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    Medium                   Maintenance is usually conducted by periodically
                                                    pumping out sediments and debris. Oil removal.
                                                    Sediment removal.
 Community                      High                Generally not visible to community or considered as
 Acceptance(2)                                      part of primary treatment facility.
 Construction Cost(3)           Medium              Dependent on type of pretreatment. High costs can be
                                                    associated with concrete structure construction and
                                                    excavation.
 Wildlife Habitat(4)            Low (none)          No habitat provided.
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                                  6
 Tool Component No. 6: Treatment Train Options
 BMP                                              Purpose                                                Upstream      Downstream
 Oil control facilities are considered a pretreatment BMP. Pretreatment BMPs are selected on a prescriptive basis for
 projects/sites where substantial amount of oil and grease concentrations in stormwater exist. Oil control facilities should be
 designed off-line to treat the water quality design storm. Oil control facilities should NOT be located downstream of conveyance
 facilities that introduce turbulence and consequently promote emulsification. In addition, pumping devices must be located
 downstream from oil/water separators. See also App. L - Proprietary Facilities.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                              X
 Storm/sanitary sewer system maintenance                                                                      X
 Proper vehicle washing and management practices                                                              X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                    X
 Limit clearing and grading of forests and native vegetation.                                                 X
 Manage a fixed portion of community open space as protected green space.                                     X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
 Minimize lane widths based on traffic volume.                                                                X
 Provide stormwater treatment, wherever possible, that can be integrated into required                        X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                X
 Minimize runoff through low impact development design including pervious pavement, water                     X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                          X              X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X              X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X              X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                              X              X
 Water Quality**
  Provides pretreatment for swale influent or additional treatment for swale effluent
  Some water quality BMPs also provide additional storage
 Sediment removal (pretreatment to reduce sediment loading)                                                   X
 Swale in series or parallel (provides additional capacity for larger water quality volumes)                  X              X
 Wet Ponds (additional treatment for metals, nutrients)                                                                      X
 Wetlands (additional treatment for metals, nutrients)                                                                       X
 Media Filter (pretreatment for sediment, metals, nutrients)                                                  X              X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Hydraulic structures (reduce velocity of runoff entering the oil control facilities)                         X              X
 Infiltration trench/pond                                                                                                    X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                            7
Pretreatment – Sediment Control
Description
Pretreatment, a first step in the pollutant removal process, is often considered when the unit
operation would benefit from an easy to maintain internal or external structure to improve the
unit’s efficiency and lifespan. Sediment control is a form of pretreatment that provides a location
for the coarse sediment carried by the stormwater to settle in a location that will not adversely
affect the rest of the treatment process. It can often be beneficial to include this treatment feature
to minimize annual maintenance costs and extend the life and efficiency of the facility.
Sediment control features can be integrated into the structure of the larger treatment facility or
installed as a step in the treatment process, also called a ―unit operation‖, in a multiple facility
treatment system. The three most common pretreatment facilities are all designed for sediment
control:

      Forebay or wet pool – Forebays and wet pools are smaller detention facilities physically
       connected to larger treatment facilities
      Pollution control manhole - Large sediment particles and debris small enough to fit in the
       inlet pipe settle to the bottom of the manhole (Note: pollution control manholes not
       designed as pretreatment devices, but as entire treatment systems are discussed in
       Appendix M, Proprietary Facilities)
      Sedimentation basin - a facility sized to reduce heavy sediment loads that may disrupt
       runoff treatment facilities. Settled runoff cannot be discharged directly to a receiving
       water without additional treatment. Considerations for siting these facilities are similar to
       those for detention basins described in Chapter 12.

Application
   The need for pretreatment facilities can usually be determined by local land uses. In areas
      of high sediment loads often result from having rock quarries, nurseries, arterial roads
      and highways (especially if they are graveled in the winter), and other soil disturbing
      activities.
   Wet pool or forebay facilities are applicable for constructed treatment wetlands,
      infiltration facilities, grassed swales, and extended dry detention ponds.
   Located upstream of other engineered treatment systems.

Pollutant Removal Mechanism
    Density Separation (key treatment mechanism)
    Filtration

Primary Targeted Pollutants
    Sediments/Particulates

Secondary Targeted Pollutants
    Oil and Grease
    Metals (particulate)




                                                                                                   B-1
Schematic Detail




          Example illustration of manufactured sediment removal structure (Stormceptor®).




                     Example of a sedimentation forebay in a wet pond facility.




                                                                                            B-2
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  Low                Considered a pre-treatment device and designed to
                                                   provide removal of sediment only.
 Channel Protection             Not applicable     Considered a pre-treatment device and provides
                                                   minimal channel protection.
 Peak Discharge                 Not applicable     Considered a pre-treatment device and provides
                                                   minimal peak discharge reduction.
 Recharge                       Not applicable     Designed for separation of sediment and to not allow
                                                   infiltration.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**     Comments
 Drinking Water Protection(1) Restricted           Considered a pre-treatment device. Must combine
                                                   with other treatments
 Aquatic Species               Restricted          Considered a pre-treatment device. Must combine
 Protection(2)                                     with other treatments
 Water Quality Protection(3)   Restricted          For Sediment removal only. Considered a pre-
                                                   treatment device. Must combine with other treatments
 Wetlands Protection(4)        Restricted          Considered a pre-treatment device. Must combine
                                                   with other treatments
 Sensitive Lakes               Restricted          Considered a pre-treatment device. Must combine
 Protection(5)                                     with other treatments
*Category Notes:
(1)
    Drinking water Protection – Use the sensitive lakes category to define BMP design restrictions for surface water drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               B-3
Note: Sediment Removal is considered a pretreatment BMP. An “Overall Effectiveness Rating” is provided
below, however removal efficiencies and effluent concentration are not documented. Pretreatment BMPs
are selected on a prescriptive basis and water quality treatment levels should be based on the primary
treatment BMP selected in the treatment train. See also Tool Component No. 6.
  Tool Component No. 3: Water Quality – Effectiveness
      Parameter          Overall        Documented Removal            Statistical Difference
                      Effectiveness      Efficiency and Effluent   Between Influent-Effluent
                         Rating(1)           Concentrations             Concentrations
  Sediment/          High              Removal Efficiency:       Average influent-effluent:
  Particulate                          NA                        NA
  (Total suspended                     Effluent Conc.:           Influent-effluent EMCs:
  solids)                              NA                        NA
 Nutrients:             Not                Removal Efficiency:           Average influent-effluent:
 (Nitrogen,             applicable         TN: NA                        TP: NA
 Phosphorus)                               TP: NA                        TN: NA
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           TP: NA                       TP: NA
                                                                        TN: NA
 Hydrocarbons           Moderate           Removal Efficiency:          Average influent-effluent:
 (oil and grease)       (if oil control    NA                           NA
                        is designed        Effluent Conc.:              Influent-effluent EMCs:
                        as part of         NA                           NA
                        structure)
 Bacteria               Not                Removal Efficiency:          Average influent-effluent:
 (pathogens/E.          applicable         NA                           NA
 Coli)                                     Effluent Conc.:              Influent-effluent EMCs:
                                           NA                           NA
 Metals                 Moderate           Removal Efficiency:          Average influent-effluent:
 (particulate and       (particulate)      NA                           Cu (total): NA
 dissolved)                                                             Cu (dissolved): NA
                        Not                                             Zn (total): NA
                        Applicable                                      Zn (dissolved): NA
                        (dissolved)        Effluent Conc. (ug/L):       Influent-effluent EMCs:
                                           Cu (total): NA               Cu (total): NA
                                           Cu (dissolved): NA           Cu (dissolved): NA
                                           Zn (total): NA               Zn (total): NA
                                           Zn (dissolved): NA           Zn (dissolved): NA

 Polycyclic             Not
 Aromatic               applicable
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                B-4
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Small                 Considered a pre-treatment device only. Less 1 percent
                                                 of drainage area. Negligible except for access.
 Drainage Area(2)          Small                 Considered a pre-treatment only. 5 acres maximum;
                                                 0.2 to 5 acres preferred.
 Soil Infiltration Rate(3) Not Applicable Soil infiltration rate is not a critical factor for siting the
                           +                     facility
 Slope (gradient)(4)       Not applicable Slope is not a critical factor for siting the facility.
                           +
 Groundwater level(5)      Not applicable Depth to groundwater is not a critical factor for siting
                           +                     the facility
 Dependency on Soil        Independent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Small <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    Medium                   Maintenance is usually conducted by regularly
                                                    pumping out sediments and debris. Sediment removal.
 Community                      High                Generally not visible to community or considered as
 Acceptance(2)                                      part of primary treatment facility.
 Construction Cost(3)           Low-Medium          Dependent on type of pretreatment. High costs can be
                                                    associated with concrete structure construction and
                                                    excavation.
 Aquatic/Wildlife               Low (none)          No habitat provided.
 Habitat(4)
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                             B-5
 Tool Component No. 6: Treatment Train Options
 BMP                                             Purpose                                                 Upstream      Downstream
 Sediment Removal is considered a pretreatment BMP. Pretreatment BMPs are selected on a prescriptive basis for projects/sites
 where substantial amount of debris and sediment concentration in stormwater are present. Wet pool or forebay facilities are
 applicable for constructed treatment wetlands, infiltration facilities, grassed swales, and extended dry detention ponds. See also
 App. L - Proprietary Facilities.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                              X
 Storm/sanitary sewer system maintenance                                                                      X
 Proper vehicle washing and management practices                                                              X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                    X
 Limit clearing and grading of forests and native vegetation.                                                 X
 Manage a fixed portion of community open space as protected green space.                                     X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
 Minimize lane widths based on traffic volume.                                                                X
 Provide stormwater treatment, wherever possible, that can be integrated into required                        X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                X
 Minimize runoff through low impact development design including pervious pavement, water                     X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                          X              X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X              X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X              X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                              X              X
 Water Quality**
  Provides pretreatment for other primary treatment BMPs
 Oil control (increase oil/hydrocarbon removal)                                                               X              X
 Swale in series or parallel (provides additional capacity for larger water quality volumes)                  X
 Wet Ponds (additional treatment for metals, nutrients)                                                       X
 Wetlands (additional treatment for metals, nutrients)                                                        X
 Media Filter (pretreatment for sediment, metals, nutrients)                                                  X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Hydraulic structures (reduce velocity of runoff entering the sediment removal BMP)                           X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                          B-6
Infiltration Pond
Description
Infiltration facilities apply treatment methods that use the soil for both treatment and as a vehicle
for disposal of treated stormwater to groundwater. Basic types of infiltration facilities include the
following:

      Infiltration Trenches: An infiltration trench is an excavated channel that has been lined
       on its sides and backfilled with clean stone to form a subsurface basin. Stormwater runoff
       is conveyed into the channel and temporarily stored until it infiltrates into the soil
      Infiltration Basins: An infiltration basin is a shallow depression formed by excavation or
       berming that captures stormwater and stores it until it infiltrates into the soil.
      Bio-infiltration Swales: A bio-infiltration swale is a grassed swale that has been
       specifically designed to infiltrate stormwater rather than convey it to a surface receiving
       water. In comparison with infiltration basins, bio-infiltration swales tend to be narrower
       and include check dams to slow and pool water.

Application
   Pretreatment is required to reduce sediment loadings.
   The need to determine an appropriate design infiltration rate. This is one of the most
      important aspects of infiltration facility design.
   The underlying soil must be capable of removing pollutants from stormwater, as well as
      infiltrate at the design rate. Infiltration treatment soils must contain sufficient organic
      matter and/or clays to adsorb, decompose, and/or filter stormwater pollutants.
   Infiltration facilities cannot be located on slopes greater than 6% or in fill soils.
   For roadway application, infiltration basins are typically located at interchanges and areas
      adjacent to roadways.
   Infiltration trenches are appropriate for ultra-urban applications, particularly subsurface
      designs that are covered with grating or pavement

Pollutant Removal Mechanism
    Hydrologic Attenuation (key treatment mechanism)
    Filtration (key treatment mechanism)
    Density Separation
    Sorption
    Uptake/Storage
    Microbial Transformation

Primary Targeted Pollutants
    Sediment/Particulate
    Nutrients
    Polycyclic Aromatic Hydrocarbons (PAH)
    Metals (particulate and dissolved)

Secondary Targeted Pollutants
    Oil and Grease




                                                                                                  C-1
Schematic Detail

                   Infiltration Trench




                   Infiltration Basin




                                         C-2
BMP Selection Tool Input Ratings

 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                 Rating(1)           Comments
 Water Quality             High                Provides effective treatment for wide variety of
                                               parameters, assuming soil tool provides sorption
                                               capacity.
 Channel Protection        High                Retention provided through infiltration into porous
                                               soil
 Peak Discharge            High                Provides retention through infiltration into porous
                                               soul and reduction of peak flows.
 Recharge                  High                Provides significant infiltration through underlying
                                               soil.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category                       Applicability    Comments
 Drinking Water Protection(1)   Restricted       Provides aquifer recharge; restricted for areas
                                                 with potential stormwater point sources with
                                                 high pollutant concentrations.
 Aquatic Species Protection(2) Preferred         Provides thermal benefits
 Water Quality Protection(3)    Preferred        For some target TMDL pollutants
 Wetlands Protection(4)         Acceptable       Effective in nutrient removal; however,
                                                 opportunities for infiltration in areas where
                                                 wetlands occur is limited
 Sensitive Lakes Protection(5) Acceptable        Can be effective for nutrient removal.
*Category Notes:
(1)
    Drinking water Protection – Applies to groundwater: minimizes risk for groundwater contamination; provides aquifer recharge. Use the
sensitive lakes category to define BMP design restrictions for surface water drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3)
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               C-3
 Tool Component No. 3: Water Quality – Effectiveness
     Parameter              Overall          Documented Removal              Statistical Difference
                         Effectiveness        Efficiency and Effluent      Between Influent-Effluent
                            Rating(1)            Concentrations(2)             Concentrations3)
 Sediment/              High                Removal Efficiency:           Average influent-effluent:
 Particulate                                75-95%                        N/A
 (Total suspended                           (75%-99% FHWA, 80%-
 solids)                                    100% BES)
                                            Effluent Conc.:               Influent-effluent EMCs:
                                            17                            N/A
 Nutrients:             High                Removal Efficiency:           Average influent-effluent:
 (Nitrogen,                                 TP: 50-75% (FHWA),            TP: N/A
 Phosphorus)                                65% (MN)                      TN: N/A
                                            TN: 45-70% (FHWA),
                                            50% (MN)
                                            Effluent Conc.:              Influent-effluent EMCs:
                                            TP: N/A                      TP: N/A
                                            TN: N/A                      TN: N/A
 Hydrocarbons           Moderate            Removal Efficiency:          Average influent-effluent:
 (oil and grease)                          N/A                           NA
                                           Effluent Conc.:               Influent-effluent EMCs:
                                           N/A                           NA
 Bacteria               High                Removal Efficiency:          Average influent-effluent:
 (pathogens/E.                             75-90%                        NA
 Coli)                                     (75%-98% FHWA)
                                           Effluent Conc.:               Influent-effluent EMCs:
                                           count/100 mls E. Coli         NA
                                           effluent concentration
 Metals                 High                Removal Efficiency:           Average influent-effluent:
 (particulate and       (particulate)       75-99% trace metals           Cu (total):
 dissolved)                                 (FHWA)                        Cu (dissolved):
                        High                Cu (total): 95% (MN)          Zn (total):
                        (dissolved)         Cu (dissolved):               Zn (dissolved):
                                            Zn (total): 95 % (MN)
                                            Zn (dissolved):
                                            Effluent Conc. (ug/L):        Influent-effluent EMCs:
                                            Cu (total): 4.8               Cu (total):
                                            Cu (dissolved):               Cu (dissolved):
                                            Zn (total): 39                Zn (total):
                                            Zn (dissolved):               Zn (dissolved):
 Polycyclic             High
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal varies widely, due in part to different sizing criteria, underlying soil conditions and design features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). Refer to
BMP Selection Process document for basis of statistical analysis.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                C-4
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Low-Medium            2 to 4 percent of drainage area. Also can be placed in confined spaces if
                                                 necessary. Trench is more applicable to confined spaces and urban
                                                 settings.
 Drainage Area(2)          Medium to             Trench: 2 to 10 acres maximum; Basin: 5 to 50 acres maximum. If the area
                           Large                 served is less than 2 ac, an infiltration trench is usually the preferred BMP.
                                                 Infiltration trenches are most cost-effective for small drainage areas.
 Soil Infiltration Rate(3) Medium-High           Infiltration rate must be greater than 0.52 in/hr. If a high-infiltration-rate soil
                           +++                   is not present, then the surface of the basin will become prohibitively large.
 Slope (gradient)(4)       Low ++                Typically, 6 % or less and can range from 2 % minimum (preferred) and 20 %
                                                 maximum.
 Groundwater level(5)      Medium-Deep           Buffer between the basin invert and the seasonal high groundwater level of
                           +++                   10 ft is used in some western states. For trenches, invert should be at least
                                                 4 ft above underlying bedrock and at least 4 to 8 ft over the seasonal high
                                                 groundwater elevation
 Dependency on Soil        Dependent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction

 Tool Component No. 5: Community and Environmental Factors
 Factor                   Rating(1)         Comments
 Overall Maintenance(1)   Medium            Maintenance essential to infiltrative capacity. Routine and nonroutine
                                            maintenance is required to keep infiltration basins operating effectively.
                                            Periodic maintenance includes removing debris, mowing, and revegetating
                                            eroded or barren areas.
 Community                Medium-High       Trench typically not visible to public. Can be integrated into a site's
 Acceptance(2)                              landscaping or open space. Infiltration basins add an aesthetic value to
                                            roadside areas as long as they are maintained and litter and debris are
                                            regularly removed.
 Construction Cost(3)     Medium            Infiltration facilities are moderate-cost BMPs. The principal cost to install
                                            relates to earth moving and construction costs and installation of inlet
                                            systems.
 Wildlife Habitat(4)      Trench: Low       Can provide vegetation (mostly grasses); does not provide permanent pool
                          Basin:            of water for aquatic habitat.
                          Medium
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                             C-5
 Tool Component No. 6: Treatment Train Options
 BMP                                               Purpose                                                 Upstream       Downstream
 Infiltration practices may be located at the end of the treatment train or they can be designed as off-line configurations where the
 water quality volume is diverted to the infiltration practice. In applications where the stormwater runoff has a particularly high
 pollutant load or where the soils have very high infiltration rates, a significant amount of pre-treatment should be provided to
 protect groundwater quality. Often, infiltration basins are designed as stand-alone facilities to provide water quality management-
 a design that infiltrates the 2-year runoff event. As an alternative, infiltration basins are sometimes combined with detention
 ponds to provide both stormwater quality and quantity management.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                                X
 Storm/sanitary sewer system maintenance                                                                        X
 Proper vehicle washing and management practices                                                                X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                      X
 Limit clearing and grading of forests and native vegetation.                                                   X
 Manage a fixed portion of community open space as protected green space.                                       X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                    X
 Minimize lane widths based on traffic volume.                                                                  X
 Provide stormwater treatment, wherever possible, that can be integrated into required                          X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                  X
 Minimize runoff through low impact development design including pervious pavement, water                       X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                            X                X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                    X                X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls                 X                X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                                X                X
 Water Quality**
  Pretreatment is highly recommended to remove sediments and extend life of infiltration facilities
  Provides pretreatment for trench/basin influent or additional treatment for trench/basin effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                                 X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                          X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Swales for water quantity control, overflow management                                                         X                X
 Hydraulic structures to reduce runoff quantity                                                                 X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                          C-6
Bioslope
Description

Bioslopes were developed by the Washington State Department of Transportation (WSDOT) to
treat highway runoff in areas with limited right-of-way. Bioslopes are flow-through, non-
structural BMPs that use physical straining or filtration, sorption, carbonate precipitation,
vegetative uptake, and microbial degradation to provide stormwater treatment. There are four
components to the BMP:
     Gravel zone with no vegetation that acts as a flow spreader,
     Vegetated filter strip that can incorporate soil amendments,
     Ecology-mix bed, and
     Gravel under drain trench with perforated pipe (if needed).

The gravel ―no-vegetation zone‖ is a shallow trench adjacent to the roadway pavement that acts
as a stormwater collector, filter, and flow spreader. It should be between 1 and 3 feet wide and
the depth depends upon the roadway geometry. After flowing through the no-vegetation zone,
stormwater passes into the vegetated filter strip. The width of the filter strip depends upon the
available right-of-way width, but should be at least 3 feet wide. Amending filter strip soils with
compost is recommended to increase infiltrative capacity and removal of dissolved contaminants.
After the filter strip the stormwater flows into the ecology-mix bed which is a geo-textile lined
trench including gravel under drain (with perforated pipe if necessary) covered with at least 12
inches of ecology mix. Ecology mix contains crushed rock (between 3/8-inch and #10 sieve) and
three amendments: dolomite, gypsum, and perlite. These materials allow ion exchange,
precipitation, and sorption to occur within the ecology mix. Stormwater that has passed through
the pervious stages and not infiltrated will pass into the gravel under drain which conveys the
remaining stormwater to either infiltrate here, or continue to a stormwater outfall.

Areas where Bioslopes are not appropriate include steep or unstable slopes, shallow
groundwater, or on areas containing wetlands. Steep slopes encourage material transport through
the embankment and can significantly shorten flow-through rates. Bioslopes should not be
installed on lateral slopes greater than 5 percent and longitudinal slopes less than 4H:1V. If
slopes are suspected or observed to be unstable, consult a geotechnical engineer. Shallow
groundwater areas should be avoided as they can prohibit infiltration. For roadside right-of-way
that is adjacent to wetlands, an interception trench or under drain must be included in the
bioslope design. Wetlands and wetland buffers should never be replaced with bioslopes.

Maintenance on bioslopes is very similar to normal roadside maintenance operations. Noxious
weed control is the most frequent maintenance required and herbicides should not be used on the
embankment is in a critical aquifer recharge area for drinking water supply. Studies by
Washington State Department of Transportation have not observed significant loss of infiltrative
or pollutant removal capacity over the life of their bioslopes.

Application
   Highway right-of-ways with limited space; for medians double bioslopes can be used.




                                                                                               E-1
      Applicable in situations where minimal maintenance effort is desired.
      More locations may be applicable as bioslopes provide high levels of treatment for TSS,
       metals, and nutrients.

Pollutant Removal Mechanism
    Hydrologic Attenuation (key treatment mechanism)
    Sorption (key treatment mechanism)
    Filtration (key treatment mechanism)
    Density Separation
    Uptake/Storage
    Microbial Transformation


Primary Targeted Pollutants
    Sediment/Particulate
    Nutrients
    Polycyclic Aromatic Hydrocarbons (PAH)
    Metals (particulate and dissolved)

Secondary Targeted Pollutants
    Oil and Grease




                                                                                           E-2
Schematic Detail (from WSDOT Highway Runoff Manual, 2006)




                                                            E-3
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  High               Effective at removing suspended solids, dissolved
                                                   solids, nutrients (including phosphorous), heavy
                                                   metals, and hardness (carbonates).
 Channel Protection             Medium             Provides storage and infiltration to effectively protect
                                                   channels.
 Peak Discharge                 Medium             Provides storage and infiltration to effectively reduce
                                                   peak discharges.
 Recharge                       High               Provides storage and infiltration to effectively provide
                                                   recharge.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**           Comments
 Drinking Water Protection(1) Acceptable                 Provides pollutant removal.
 Aquatic Species               Preferred                 Provides detention and infiltration; neutral for
 Protection(2)                                           temperature benefits.
 Water Quality Protection(3)   Preferred                 Dependent on the type of impairment (water quality
                                                         parameter); effective for TSS and metals; limited
                                                         benefit for temperature.
 Wetlands Protection(4)            Preferred             Variable nutrient removal.
 Sensitive Lakes                   Preferred             Variable nutrient (phosphorus) removal.
 Protection(5)
*Category Notes:
(1)
    Drinking water Protection – For groundwater; use the sensitive lakes category to define BMP design restrictions for surface water drinking
supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               E-4
 Tool Component No. 3: Water Quality – Effectiveness
     Parameter          Overall        Documented Removal                   Statistical Difference
                     Effectiveness      Efficiency and Effluent           Between Influent-Effluent
                        Rating(1)          Concentrations(2)                 Concentrations(3)
 Sediment/          High              Removal Efficiency:                Average influent-effluent:
 Particulate                          96%                                NO
 (Total suspended
 solids)                              Effluent Conc.:                   Influent-effluent EMCs:
                                      5.0 - 25* mg/L                    NO
 Nutrients:             High               Removal Efficiency:           Average influent-effluent:
 (Nitrogen,                                TP: 86%                       TP: NO
 Phosphorus)                               TN: 35%*                      TN: NO
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           TP: 0.04 - 0.3* mg/L         TP: YES
                                           TN: 0.7 mg/L*                TN: NO
 Hydrocarbons           Moderate           Removal Efficiency:          Average influent-effluent:
 (oil and grease)                          80%
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           0.75 mg/L
 Bacteria               Low                Removal Efficiency:          Average influent-effluent:
 (pathogens/E.                             35%
 Coli)                                     Effluent Conc.:              Influent-effluent EMCs:

 Metals                 High               Removal Efficiency:           Average influent-effluent:
 (particulate and       (particulate)      Cu (total): 86%               Cu (total): NO
 dissolved)                                Cu (dissolved): 39%           Cu (dissolved): NO
                        High               Zn (total): 85%               Zn (total): YES
                        (dissolved)        Zn (dissolved): 79%           Zn (dissolved): NO
                                           Effluent Conc. (ug/L):       Influent-effluent EMCs:
                                           Cu (total): 9.8               Cu (total): YES
                                           Cu (dissolved): 7.1           Cu (dissolved): YES
                                           Zn (total): 35                Zn (total): YES
                                           Zn (dissolved): 25           Zn (dissolved): YES
 Polycyclic             High
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal varies widely, due in part to different sizing criteria, underlying soil conditions and design features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). Refer to
BMP Selection Process document for basis of statistical analysis.

Data Sources:
WSDOT, 2006. Technology Evaluation and Engineering Report - WSDOT Ecology Embankment
http://www.wsdot.wa.gov/NR/rdonlyres/3D73CD62-6F99-45DD-B004-D7B7B4796C2E/0/EcologyEmbankmentTEERfinal.pdf
*NCHRP, 2006.”6.0 Bioslope” from Low Impact Design Manual for Highway Runoff Control




                                                                                                                                                E-5
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Medium                25 percent of drainage area. In most applications, ecology
                                                 embankments are placed adjacent to roadways. Minimum flow
                                                 length limits for ecology embankments is 25 ft. Gradient, width, and
                                                 length can be set based on local constraints.
 Drainage Area(2)          Medium                Maximum recommended overland flow distance should not be more
                                                 than 75 ft for an impervious service area or 150 ft for a pervious
                                                 service area.
 Soil Infiltration Rate(3) High                  Infiltration is not a key removal mechanism for ecology
                                                 embankment and is generally not a constraint. Filter strip section
                                                 requires sheet flow across the entire strip.
 Slope (gradient)(4)       Low ++                Surface slope be between 2-6% percent Maximum slope of 20%
                                                 along length. By design, ecology embankments are relatively
                                                 flexible BMPs; the gradient, width, and length can be set based on
                                                 local constraints.
 Groundwater level(5)      Low ++                Groundwater depth is not a key constraint or siting factor for
                                                 ecology embankments, as long as permanent pools are not
                                                 developed in the ecology mix. Typically 3 ft to groundwater is
                                                 acceptable.
 Dependency on Soil        Independent           If soils have low infiltrative capacity, a conveyance pipe must be
 Characteristics(6)                              included in the under drain below the ecology mix.
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    To be                    Periodic maintenance for ecology embankments is
                           determined               primarily focused maintaining vegetation, preventing
                                                    the formation of rills and gullies, and removing debris
                                                    and litter.
 Community                      High                Add an aesthetic value to roadside areas as long as
 Acceptance(2)                                      they are maintained and litter and debris are regularly
                                                    removed
 Construction Cost(3)           Medium              The principal cost to install is related to earth moving
                                                    construction costs and planting costs.
 Aquatic/Wildlife               Low                 Vegetated area comprised primarily of grasses and
 Habitat(4)                                         provide poor wildlife habitat; no exposed surface water
                                                    for aquatic habitat.
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.




                                                                                                                                             E-6
**Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                              E-7
 Tool Component No. 6: Treatment Train Options
                                                                                                         Upstream Downstream
 Ecology embankments can provide excellent treatment as a stand-alone treatment device as they incorporate several treatment
 techniques into one unit. They can be used upstream of other treatment BMPs and the ecology embankment lifespan can be
 increased through the use of roadway maintenance practices.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                              X
 Storm/sanitary sewer system maintenance                                                                      X
 Proper vehicle washing and management practices                                                              X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                    X
 Limit clearing and grading of forests and native vegetation.                                                 X
 Manage a fixed portion of community open space as protected green space.                                     X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
 Minimize lane widths based on traffic volume.                                                                X
 Provide stormwater treatment, wherever possible, that can be integrated into required                        X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                X
 Minimize runoff through low impact development design including pervious pavement, water                     X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                          X         X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X         X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X         X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                              X         X
 Water Quality**
  Provides pretreatment for ecology embankment influent or additional treatment for ecology embankment effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                               X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                        X
 Wet Ponds (additional treatment for metals, nutrients)                                                                 X
 Wetlands (additional treatment for metals, nutrients)                                                                  X
 Swale (additional treatment for sediment, metals, nutrients and conveyance)                                            X
 Media Filter (pretreatment for sediment, metals, nutrients)                                                  X         X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Hydraulic structures (reduce velocity of runoff entering the ecology embankment)                             X         X
 Infiltration trench/pond                                                                                               X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                          E-8
Porous Pavement (not stand alone)
Description

Porous pavement is a stormwater best management practice that integrates natural hydrological
functions into design. Natural processes of storage, detention, infiltration, evaporation, and
transpiration are replicated in order to reduce runoff volumes, attenuate peak runoff rates, and
filter and remove pollutants from runoff. Porous pavement is not considered an ―end-of-pipe‖
BMP. It functions to reduce the runoff generated and pollutant loading requiring treatment by
other runoff treatment BMPs. Three types of porous pavement design are considered applicable
to roadway projects:
      Porous pavement—pervious concrete or asphalt mixes that are applied in lieu of
       conventional impervious concrete or asphalt pavement mixes.
      Porous pavers—concrete block surface treatments that are installed with open spaces
       between each paver. The open space is typically filled with gravel, sand, or grass.
      Roadside channels—conventional open ditches that may achieve some minimal
       improvement to water quality.

Application
   Areas of light traffic, parking lots, and shoulders of roadways and highways. Porous
      pavement is also recommended on bicycle trails, sidewalks, and related pedestrian use
      areas.
   Use at gas stations, truck stops, and industrial sites is not recommended due to the high
      risk of groundwater contamination from trace organic compounds
   Drainage areas less than 15 acres.
   May be restricted in cold regions, areas with high wind erosion rates, and areas of sole-
      source aquifers.

Pollutant Removal Mechanism
    Hydrologic Attenuation

Targeted Pollutants
    Sediment/Particulate
    Nutrients
    Oil and Grease
    Polycyclic Aromatic Hydrocarbons (PAH)
    Metals (particulate and dissolved)




                                                                                             E-1
Schematic Detail




                            Schematic of Porous Pavement Application
(taken from Stormwater Best Management Practices in an Ultra-Urban Setting: Selection and Monitoring, FHWA;
http://www.fhwa.dot.gov/environment/ultraurb )




                                                                                                          E-2
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  Medium             LID results in increased infiltration and reduction of
                                                   runoff to carry pollutant loads and filter pollutants.
 Channel Protection             Medium-High        Provides added benefits to projects with site
                                                   constraints for locating or constructing end-of-pipe
                                                   detention facilities.
 Peak Discharge                 Medium-High        Provides added benefits to projects with site
                                                   constraints for locating or constructing end-of-pipe
                                                   detention facilities.
 Recharge                       High               Primary function is to increase infiltration to store,
                                                   detain, evaporate and transpire storm flows.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**     Comments
 Drinking Water Protection(1) Restricted           May not want to apply in areas with known hot spots
                                                   for pollutant sources. Sites that are probable sources
                                                   of high contaminant loads, such as gas stations,
                                                   should be avoided. Install no closer to drinking water
                                                   wells than 100 ft.
 Aquatic Species               Preferred           Promotes baseflow and reduces stream temperature
 Protection(2)                                     impacts.
 Water Quality Protection(3)   Preferred           Reduces runoff volume and pollutant loading; also
                                                   provides some direct water quality treatment through
                                                   infiltration/sorption process. Porous pavements are
                                                   as effective at removing pollutants from stormwater
                                                   as other infiltration devices.
 Wetlands Protection(4)        Acceptable          Reduces runoff volume and pollutant loading;
                                                   promotes baseflow; limited nutrient removal.
 Sensitive Lakes               Acceptable          Reduces runoff volume and pollutant loading;
 Protection(5)                                     promotes baseflow; limited nutrient removal.
*Category Notes:
(1)
    Drinking water Protection – Applied to groundwater. Use the sensitive lakes category to define BMP design restrictions for surface water
drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               E-3
 Tool Component No. 3: Water Quality – Effectiveness of Porous Pavements
     Parameter          Overall        Documented Removal              Statistical Difference
                     Effectiveness      Efficiency and Effluent     Between Influent-Effluent
                        Rating(1)          Concentrations(2)            Concentrations(3)
 Sediment/          Moderate          Removal Efficiency:         Average influent-effluent:
 Particulate                          70%                         NA
 (Total suspended                     (82%-95% FHWA)
 solids)                              Effluent Conc.:             Influent-effluent EMCs:
                                      42 mg/L                     NA
 Nutrients:             Moderate           Removal Efficiency:           Average influent-effluent:
 (Nitrogen,                                TN: 80%-85%                   TP: NA
 Phosphorus)                               TP: 60%-80%                   TN: NA
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           TP: NA                       TP: NA
                                                                        TN: NA
 Hydrocarbons           Moderate           Removal Efficiency:          Average influent-effluent:
 (oil and grease)                          NA                           NA
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           NA                           NA
 Bacteria               Moderate           Removal Efficiency:          Average influent-effluent:
 (pathogens/E.                             NA                           NA
 Coli)                                     Effluent Conc.:              Influent-effluent EMCs:
                                           NA                           NA
 Metals                 Moderate           Removal Efficiency:          Average influent-effluent:
 (particulate and       (particulate)      90% (not specified)          Cu (total):
 dissolved)                                (33-99% FHWA)                Cu (dissolved):
                        Low                                             Zn (total):
                        (dissolved)                                     Zn (dissolved):
                                           Effluent Conc. (ug/L):       Influent-effluent EMCs:
                                           Cu (total): NA               Cu (total): NA
                                           Cu (dissolved): NA           Cu (dissolved): NA
                                           Zn (total): NA               Zn (total): NA
                                           Zn (dissolved): NA           Zn (dissolved): NA

 Polycyclic             Moderate
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal varies widely, due in part to different sizing criteria, underlying soil conditions and design features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). Refer to
BMP Selection Process document for basis of statistical analysis.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                E-4
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Low                   BMP area typically underlies the entire contributing
                                                 surface area (to be infiltrated).
 Drainage Area(2)          Small                 Applied to discrete areas within a development or
                                                 roadway project.
 Soil Infiltration Rate(3) Medium ++             Minimum soil infiltration capacity of 0.27 in/h (greater
                                                 than (0.5 in/h is preferred).
 Slope (gradient)(4)       Low++                 Lower gradient promotes infiltration and less runoff.
 Groundwater level(5)      Medium ++             Should not interfere or limit infiltration rate.
                                                 Groundwater contamination can be minimized by
                                                 ensuring that the depth to the seasonally high water
                                                 tables is at least 4 ft below the reservoir layer.
 Dependency on Soil        Dependent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    To be                    Maintenance required to maintain infiltration rates
                           determined               (vacuum sweeping in conjunction with jet hosing).
                                                    Like other infiltration BMPs, porous pavements are not
                                                    designed to sustain a high removal rate for suspended
                                                    sediment.
 Community                      Medium              Not considered standard practice in industry and
 Acceptance(2)                                      construction.
 Construction Cost(3)           Medium              Costs for specialized asphalt/concrete is higher than
                                                    standard materials. Requirements for site preparation
                                                    or the use of specialized equipment may also increase
                                                    these costs. Higher costs of installation can be offset
                                                    to some extent by the elimination of curbs, gutters, and
                                                    storm drains.
 Aquatic/Wildlife               Low                 Most LID options provide limited vegetation and
 Habitat(4)                                         provide no permanent pools for aquatic habitat.
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                             E-5
 Tool Component No. 6: Treatment Train Options
 BMP                                             Purpose                                                 Upstream  Downstream
 LID structural practices (e.g. porous pavements) are categorized under the “Site Design/Development category below. Other
 structural flow control and runoff treatment BMPs are installed downstream of LID practices to address remaining water quantity
 and quality volumes not infiltrated by the LID practice.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                              X
 Storm/sanitary sewer system maintenance                                                                      X
 Proper vehicle washing and management practices                                                              X
 Site Design/Development* (LID “structural” practices generally fall in this category)
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                    X
 Limit clearing and grading of forests and native vegetation.                                                 X
 Manage a fixed portion of community open space as protected green space.                                     X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                          X           X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X           X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X           X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                              X           X
 Water Quality**
  Provides pretreatment for swale influent or additional treatment for swale effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                                           X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                                    X
 Swale in series or parallel (provides additional capacity for larger water quality volumes)                              X
 Wet Ponds (additional treatment for metals, nutrients)                                                                   X
 Wetlands (additional treatment for metals, nutrients)                                                                    X
 Media Filter (pretreatment for sediment, metals, nutrients)                                                              X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Detention Pond                                                                                                           X
 Infiltration trench/pond                                                                                                 X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                          E-6
Grass Swale
Description
Grassed swales are artificial open channels engineered to treat stormwater by sedimentation and
filtration as the conveyed stormwater runoff flows through the vegetated (typically grass) and
soil surface. Grassed swales are popular because of their low construction and maintenance cost
and few design limitations. They can be located in median strips, along the shoulders of
roadways, and parking lots. The five swale types are:

      Basic grassed swale - designed to provide water quality control only.
      Combination grassed swale - designed to provide water quality control and high flow
       conveyance
      Continuous grassed swale - designed similar to basic grassed swales except that runoff
       can enter anywhere along the length of the swale
      Combination continuous grassed swale - designed similar to combination grassed swales
       except runoff can enter anywhere along the length of the swale
      Bioinfiltration swale – designed to utilize infiltration as well as vegetative filtration, and
       due to the infiltration the downstream flows are reduced and often the swale can be sized
       smaller than a standard grassed swale (also covered in Appendix I – Infiltration).

Application
   Most applicable for impervious areas of five acres or less.
   Can be designed inline for both conveyance and water quality treatment.
   Typically designed for a storm return interval of 10 years for flow conveyance and
      storage.
   Can be designed using amended soil (see Section N) to enhance removal of dissolved
      pollutants.

Pollutant Removal Mechanism
    Filtration (key treatment mechanism)
    Sorption (key treatment mechanism with amended soil)
    Hydrologic Attenuation
    Density Separation
    Uptake/Storage
    Microbial Transformation

Primary Targeted Pollutants
    Sediment/Particulate
    Metals (particulate)
    Metals (dissolved) (using amended soil)

Secondary Targeted Pollutants
    Nutrients
    Oil and Grease
    Polycyclic Aromatic Hydrocarbons (PAH)




                                                                                                  F-1
Schematic Detail




                   F-2
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  Medium             Provides treatment for water quality design flow rate
                                                   and effective for TSS and heavy metals.
 Channel Protection             None               Retention provided through infiltration into porous
                                                   soil; detention provided through surface ponding and
                                                   storage in soil and gravel layers.
 Peak Discharge                 None               Provides storage mechanism through infiltration and
                                                   surface ponding in underdrain.
 Recharge                       Low                Provides infiltration through underlying soil (and
                                                   underdrain if present) and exfiltration into subsoil.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**           Comments
 Drinking Water Protection(1) Acceptable                 Provides limited recharge; provides pollutant removal
 Aquatic Species               Acceptable                Provides limited detention and infiltration (dependent
 Protection(2)                                           on soil infiltration rate); neutral for temperature
                                                         benefits.
 Water Quality Protection(3)       Acceptable            Dependent on the type of impairment (water quality
                                                         parameter); effective for TSS and meals; limited
                                                         benefit for temperature.
 Wetlands Protection(4)            Acceptable            Limited nutrient removal, no extended detention
                                                         periods.
 Sensitive Lakes                   Restricted            Limited nutrient removal.
 Protection(5)
*Category Notes:
(1)
    Drinking water Protection – Applies to groundwater. Use the sensitive lakes category to define BMP design restrictions for surface water
drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               F-3
 Tool Component No. 3: Water Quality – Effectiveness
     Parameter          Overall           Overall             Documented Removal               Statistical Difference
                     Effectiveness    Effectiveness           Efficiency and Effluent        Between Influent-Effluent
                     Rating without     Rating with              Concentrations(2)              Concentrations(3)
                       Amended          Amended
                         Soil(1)           Soil(1)
 Sediment/          High              High                   Removal Efficiency:           Average influent-effluent:
 Particulate                                                 50%-80%                       NO (NRCH) / YES (IBMPD)
 (Total suspended                                            30%-90% (FHWA)
 solids)                                                     Effluent Conc.:               Influent-effluent EMCs:
                                                             24-37.99 mg/L                 NO
 Nutrients:             Moderate           Moderate          Removal Efficiency:           Average influent-effluent:
 (Nitrogen,                                                  TN: 50%-80%                   TP: NO (NRCH) / YES
 Phosphorus)                                                 (0%-50% FHWA)                 (IBMPD)
                                                             TP: 50%-80%                   TN: NO
                                                             (20%-85% FHWA)
                                                             Effluent Conc.:               Influent-effluent EMCs:
                                                             TP: 0.21-0.37 mg/L            TP: YES (NRCH) / NO
                                                             TN: 0.69-0.71 mg/L            (IBMPD)
                                                                                           TN: NO
 Hydrocarbons           Moderate           Moderate          Removal Efficiency:           Average influent-effluent:
 (oil and grease)                                            <80%                          N/A
                                                             75% (FHWA)
                                                             Effluent Conc.:               Influent-effluent EMCs:
                                                             N/A                           N/A
 Bacteria               Not                Not               Removal Efficiency:           Average influent-effluent:
 (pathogens/E.          Applicable         Applicable        <35%                          N/A
 Coli)                                                       (N/A FHWA)
                                                             Effluent Conc.:               Influent-effluent EMCs:
                                                             3,584 – 916 count/100         N/A
                                                             mL E. Coli
 Metals                 High               High              Removal Efficiency:           Average influent-effluent:
 (particulate and       (particulate)      (particulate)     30%-65%                       Cu (total): NO (NRCH) /
 dissolved)                                                  (0% to 90% FHWA)              YES (IBMPD)
                        Moderate           High                                            Cu (dissolved): NO
                        (dissolved)        (dissolved)                                     Zn (total): YES
                                                                                           Zn (dissolved): YES
                                                             Effluent Conc. (ug/L):        Influent-effluent EMCs:
                                                             Cu (total): 10.01-15.01       Cu (total): YES
                                                             Cu (dissolved): 5.7-9.68      Cu (dissolved): YES
                                                             Zn (total): 48-60.23          Zn (total): NO (NRCH) /
                                                             Zn (dissolved): 20-           YES (IBMPD)
                                                             31.96                         Zn (dissolved): YES

 Polycyclic             Moderate           Moderate
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal varies widely, due in part to different sizing criteria, underlying soil conditions and design features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). Refer to
BMP Selection Process document for basis of statistical analysis.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                F-4
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Medium                10 to 20 percent of drainage area. Minimum length =
                                                 100 ft. to minimize flow rates and allow appropriate
                                                 residence times.
 Drainage Area(2)          Medium                5-10 acre maximum. Larger areas may require flow
                                                 splitters or multiple parallel swales.
 Soil Infiltration Rate(3) Low ++                Should be well drained to prevent ponding; infiltration
                                                 rate can be altered with media mix.
 Slope (gradient)(4)       Low +++               Slope: 1% to 6% to ensure adequate flow rate within
                                                 the channel and to prevent scouring and eroding of
                                                 channel.
 Groundwater level(5)      Medium ++             Around 3 ft depth to GW (or bedrock); prevents
                                                 groundwater from seeping upward into the cell (or
                                                 perching on impervious layer).
 Dependency on Soil        Dependent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    Low                      Routine mowing. Sediment removal. Weed control.
 Community                 Medium                   Provides neutral to positive visual impact; grassed and
 Acceptance(2)                                      vegetated; can blend in with other landscaping.
 Construction Cost(3)      Low-Medium               Readily available materials; standard construction
                                                    practices; limited grading and excavation needed for
                                                    appropriate sites.
 Wildlife Habitat(4)            Medium              Vegetated area comprised primarily of grasse and
                                                    provide poor wildlife habitat; no exposed surface water
                                                    for aquatic habitat.
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                             F-5
 Tool Component No. 6: Treatment Train Options
 BMP                                               Purpose                                               Upstream Downstream
 Swales can provide supplementary or complementary benefits; can serve as pretreatment areas for conventional stormwater
 detention or infiltration facilities or other water quality BMPs.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                              X
 Storm/sanitary sewer system maintenance                                                                      X
 Proper vehicle washing and management practices                                                              X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                    X
 Limit clearing and grading of forests and native vegetation.                                                 X
 Manage a fixed portion of community open space as protected green space.                                     X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
 Minimize lane widths based on traffic volume.                                                                X
 Provide stormwater treatment, wherever possible, that can be integrated into required                        X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                X
 Minimize runoff through low impact development design including pervious pavement, water                     X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                          X        X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X        X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X        X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                              X        X
 Water Quality**
  Provides pretreatment for swale influent or additional treatment for swale effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                               X        X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                        X
 Swale in series or parallel (provides additional capacity for larger water quality volumes)                  X        X
 Wet Ponds (additional treatment for metals, nutrients)                                                                X
 Wetlands (additional treatment for metals, nutrients)                                                                 X
 Media Filter (pretreatment for sediment, metals, nutrients)                                                  X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Hydraulic structures (reduce velocity of runoff entering the swale)                                          X        X
 Infiltration trench/pond                                                                                              X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                          F-6
Filter Strip
Description

Filter strips are treatment facilities that can remove pollutants by sedimentation and filtration.
Also called buffer strips or biofilters, filter strips are designed to treat sheet flow from an
adjacent roadway and treatment occurs as the stormwater runoff flows through the grass and soil
surface. Because of their minimalist right-of-way requirements and maintenance schedule, filter
strips are extremely popular stormwater runoff BMPs for highway application.

Application
   Generally most applicable to linear applications such as roads and highways.
   Applicable in situations where minimal maintenance effort is desired (provided grass
      cover can be maintained all year without irrigation).
   Commonly operated as a pre-treatment BMP located upstream of other BMPs capable of
      greater pollutant removal rates
   Can be designed using amended soil (see Section N) to enhance removal of dissolved
      pollutants.

Pollutant Removal Mechanism
    Filtration (key treatment mechanism)
    Sorption (key treatment mechanism with amended soil)
    Hydrologic Attenuation
    Density Separation
    Uptake/Storage
    Microbial Transformation

Primary Targeted Pollutants
    Sediment/Particulate
    Metals (particulate)
    Metals (dissolved) (using amended soil)

Secondary Targeted Pollutants
    Nutrients
    Oil and Grease
    Polycyclic Aromatic Hydrocarbons (PAH)




                                                                                               G-1
Schematic Detail




                   G-2
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  Medium             Effective at removing suspended solids, less effective
                                                   at removing dissolved solids
 Channel Protection             None               Does not provide enough storage or infiltration to
                                                   effectively protect channels.
 Peak Discharge                 None               Does not provide enough storage or infiltration to
                                                   effectively reduce peak discharges
 Recharge                       Low                Does not provide enough storage or infiltration to
                                                   effectively provide recharge.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**           Comments
 Drinking Water Protection(1) Acceptable                 Provides limited recharge; provides pollutant removal
 Aquatic Species               Acceptable                Provides limited detention and infiltration (dependent
 Protection(2)                                           on soil infiltration rate); neutral for temperature
                                                         benefits.
 Water Quality Protection(3)       Acceptable            Dependent on the type of impairment (water quality
                                                         parameter); effective for TSS and metals; limited
                                                         benefit for temperature.
 Wetlands Protection(4)            Acceptable            Limited nutrient removal; no extended detention
                                                         periods.
 Sensitive Lakes                   Restricted            Limited nutrient (phosphorus) removal
 Protection(5)
*Category Notes:
(1)
    Drinking water Protection – For groundwater; use the sensitive lakes category to define BMP design restrictions for surface water drinking
supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               G-3
 Tool Component No. 3: Water Quality – Effectiveness
     Parameter          Overall           Overall              Documented Removal              Statistical Difference
                     Effectiveness    Effectiveness            Efficiency and Effluent       Between Influent-Effluent
                     Rating without     Rating with               Concentrations(2)             Concentrations(3)
                       Amended          Amended
                         Soil(1)           Soil(1)
 Sediment/          High              High                   Removal Efficiency:           Average influent-effluent:
 Particulate                                                 70%-80%                       NO (NRCH) / YES (IBMPD)
 (Total suspended                                            27%- 70% (FHWA)
 solids)                                                     Effluent Conc.: 24.6-         Influent-effluent EMCs:
                                                             37.99 mg/L                    NO
 Nutrients:             Moderate           Moderate          Removal Efficiency:            Average influent-effluent:
 (Nitrogen,                                                  TP: 50%                        TP: YES (NRCH) / NO
 Phosphorus)                                                 TN: 35%                        (IBMPD)
                                                             20%-40% (FHWA)                 TN: NO
                                                             Effluent Conc.:               Influent-effluent EMCs:
                                                             TP: 0.32-0.37 mg/L            TP: NO (NRCH) / YES
                                                             TN: 0.69-0.71 mg/L            (IBMPD)
                                                                                           TN: NO
 Hydrocarbons           Moderate           Moderate          Removal Efficiency:           Average influent-effluent:
 (oil and grease)                                            80%
                                                             Effluent Conc.:               Influent-effluent EMCs:

 Bacteria               Not                Not               Removal Efficiency:           Average influent-effluent:
 (pathogens/E.          Applicable         Applicable        35%
 Coli)                                                       Effluent Conc.:               Influent-effluent EMCs:

 Metals                 High               High              Removal Efficiency:           Average influent-effluent:
 (particulate and       (particulate)      (particulate)     50%                           Cu (total): NO (NRCH) /
 dissolved)                                                  2%-80% (FHWA)                 YES (IBMPD)
                        Moderate           High                                            Cu (dissolved): NO
                        (dissolved)        (dissolved)                                     Zn (total): YES
                                                                                           Zn (dissolved): NO
                                                                                           (NRCH) / YES (IBMPD)
                                                             Effluent Conc. (ug/L):        Influent-effluent EMCs:
                                                             Cu (total): 10.01-15.01       Cu (total): YES
                                                             Cu (dissolved): 7.66-         Cu (dissolved): YES
                                                             9.68                          Zn (total): YES
                                                             Zn (total): 39.44-60.23       Zn (dissolved): YES
                                                             Zn (dissolved): 28.91-
                                                             31.96
 Polycyclic             Moderate           Moderate
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal varies widely, due in part to different sizing criteria, underlying soil conditions and design features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). Refer to
BMP Selection Process document for basis of statistical analysis.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                G-4
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Medium                25 percent of drainage area. In most applications, filter strips
                                                 are placed adjacent to roadways. Minimum flow length limits
                                                 for filter strips is 25 ft. Gradient, width, and length can be set
                                                 based on local constraints.
 Drainage Area(2)          Medium                Maximum recommended overland flow distance should not be
                                                 more than 75 ft for an impervious service area or 150 ft for a
                                                 pervious service area.
 Soil Infiltration Rate(3) Low ++                Infiltration is not a key removal mechanism for filter strip and
                                                 is generally not a constraint. Filter strips require sheet flow
                                                 across the entire strip.
 Slope (gradient)(4)       Medium ++             Surface slope be between 2-6% percent Maximum slope of 20%
                                                 along length. By design, filter strips are relatively flexible
                                                 BMPs; the gradient, width, and length can be set based on
                                                 local constraints.
 Groundwater level(5)      Medium ++             Groundwater depth is not a key constraint or siting factor for
                                                 filter strips, as long as permanent pools are not developed
                                                 which affects the filtering mechanism. Typically 3 ft to
                                                 groundwater is acceptable.
 Dependency on Soil        Dependent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    Low                      Periodic maintenance for filter strips is primarily focused
                                                    maintaining vegetation, preventing the formation of rills and
                                                    gullies, and removing debris and litter.
 Community                      High                add an aesthetic value to roadside areas as long as they are
 Acceptance(2)                                      maintained and litter and debris are regularly removed
 Construction Cost(3)           Low                 Filter strips are low-cost BMPs. The principal cost to install
                                                    is related to earth moving construction costs and planting
                                                    costs.
 Aquatic/Wildlife               Low                 Vegetated area comprised primarily of grasse and provide
 Habitat(4)                                         poor wildlife habitat; no exposed surface water for aquatic
                                                    habitat.
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers. (2) Community acceptance – accounts for general sense of visual preference,
reported nuisance problems, vegetative management; subjective in nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                              G-5
 Tool Component No. 6: Treatment Train Options
                                                                                                             Upstream      Downstream
 Filter strips can provide supplementary or complementary benefits. A filter strip is commonly operated as a pre-treatment BMP
 located upstream of other BMPs capable of greater pollutant removal rates. Pretreatment is not considered crucial to the removal
 performance of filter strips unless there is sufficient loading of pollutants (e.g., sand, oil and grease) to harm the vegetated
 surface.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                                  X
 Storm/sanitary sewer system maintenance                                                                          X
 Proper vehicle washing and management practices                                                                  X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                        X
 Limit clearing and grading of forests and native vegetation.                                                     X
 Manage a fixed portion of community open space as protected green space.                                         X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                      X
 Minimize lane widths based on traffic volume.                                                                    X
 Provide stormwater treatment, wherever possible, that can be integrated into required                            X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                    X
 Minimize runoff through low impact development design including pervious pavement, water                         X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                              X              X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                      X              X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls                   X              X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                                  X              X
 Water Quality**
  Provides pretreatment for filter strip influent or additional treatment for filter strip effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                                   X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                            X
 Wet Ponds (additional treatment for metals, nutrients)                                                                          X
 Wetlands (additional treatment for metals, nutrients)                                                                           X
 Media Filter (pretreatment for sediment, metals, nutrients)                                                      X              X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Hydraulic structures (reduce velocity of runoff entering the filter strip)                                       X              X
 Infiltration trench/pond                                                                                                        X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
  the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
  design, development, and construction practices in stormwater management.
** The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual BMPs. Only
  limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness information
  provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                         G-6
Constructed Wetland
Description

Stormwater treatment wetlands are shallow areas inundated or saturated by surface or
groundwater at a frequency and duration sufficient to maintain emergent vegetation adapted to
saturated soil conditions. Over time, particulate pollutants and other materials accumulate in the
wetland as sediment and must be periodically removed as part of their required maintenance.
Emergent vegetation contributes to the overall reduction of pollutants and must occasionally be
harvested to maintain a healthy growth environment and limit vegetation decay.

There are many reasons to select a stormwater treatment wetland over other engineered best
management practice facilities. Wetlands provide:
    Long contact time between stormwater and vegetation and soil to treat dissolved
       pollutants
    May provide valuable habitat to local animal species and migratory birds
    Have the potential to be better integrated aesthetically into a site because of the aquatic
       vegetation

Stormwater treatment wetlands consist of a forebay or wet pool cell for settling out the majority
of the large particulates. In the second bay, the water levels are much shallower and thickly
vegetated with emergent wetland plants. Two types of stormwater treatment wetlands are
considered in this section:
     Basic Wetland: A basic wetland provides water quality control only and is constructed
        offline, requiring a flow splitter.
     Combination Wetland: A combination wetland is constructed in-line and provides both
        water quality and water quantity control and does not require a flow splitter.

Application
   Stormwater treatment wetlands are applicable to most situations as long as enough
      appropriate land is available
   Stormwater treatment wetlands can be designed either in- or off-line although off-line is
      preferred as it protects the wetland vegetation from high flows.
   Potential sites are most likely at low-lying interchanges or medians where runoff can be
      directed to them, or existing open areas such as parks, which provide additional aesthetic
      and educational benefits.

Pollutant Removal Mechanism
    Hydrologic Attenuation
    Density Separation
    Sorption
    Filtration
    Uptake/Storage
    Microbial Transformation




                                                                                               H-1
Primary Targeted Pollutants
    Sediment/Particulate
    Nutrients
    Polycyclic Aromatic Hydrocarbons (PAH)
    Metals (particulate and dissolved)

Secondary Targeted Pollutants
    Oil and Grease




                                              H-2
Schematic Detail




                   H-3
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  High               Long retention time for settling and adsorption or
                                                   uptake by vegetation
 Channel Protection             High               Provides runoff storage; even more effective when a
                                                   combined detention pond is used.
 Peak Discharge                 High               Provides runoff storage; even more effective when a
                                                   combined detention pond is used.
 Recharge                       Low                None when impermeable liners are required or
                                                   medium when pool intercepts groundwater
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**     Comments
 Drinking Water Protection(1) Preferred
 Aquatic Species               Preferred           Provides runoff storage;
 Protection(2)
 Water Quality Protection(3)   Preferred           Properly designed wetland systems are extremely
                                                   effective at removing soluble pollutants and
                                                   particulates
 Wetlands Protection(4)        Preferred
 Sensitive Lakes               Acceptable          Generally high nutrient removal, but effectiveness
 Protection(5)                                     can be seasonably variable
*Category Notes:
(1)
    Drinking water Protection – Use the sensitive lakes category to define BMP design restrictions for surface water drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               H-4
 Tool Component No. 3: Water Quality – Effectiveness
      Parameter          Overall        Documented Removal                  Statistical Difference
                      Effectiveness     Efficiency and Effluent           Between Influent-Effluent
                         Rating(1)         Concentrations(2)                  Concentrations(3)
 Sediment/          High              Removal Efficiency:                Average influent-effluent:
 Particulate                          50-80% when influent               YES (NRCH)/NO (IBMPD)
 (Total suspended                     between 100-200 mg/L
 solids)                              (65% FHWA)
                                      Effluent Conc.:                   Influent-effluent EMCs:
                                      20 mg/L when influent             YES
                                      less than 100 mg/L
 Nutrients:          High             Removal Efficiency:                Average influent-effluent:
 (Nitrogen,                           TN: 20% (FHWA)                     TN: NO
 Phosphorus)                          TP: 25% (FHWA)                     TP: YES
                                      Effluent Conc.:                   Influent-effluent EMCs:
                                      TN: 2.42 mg/L                     TN: NO
                                      TP: 0.11-0.18 mg/L                TP: YES
 Hydrocarbons        Moderate         Removal Efficiency:               Average influent-effluent:
 (oil and grease)                     NA                                N/A
                                      Effluent Conc.:                   Influent-effluent EMCs:
                                      NA                                N/A
 Bacteria            Moderate         Removal Efficiency:               Average influent-effluent:
 (pathogens/E.                        64% (BES)                         N/A
 Coli)                                Effluent Conc.:                   Influent-effluent EMCs:
                                      499 count/100 mL                  N/A
 Metals              High             Removal Efficiency:               Average influent-effluent:
 (particulate and    (particulate)    50% (Zinc based on                Cu (total): NO
 dissolved)                           influent of 0.02-0.3              Cu (dissolved): N/A
                     High             mg/L)                             Zn (total): NO
                     (dissolved)      (35%-65% FHWA)                    Zn (dissolved):
                                           Effluent Conc. (ug/L):       Influent-effluent EMCs:
                                           Cu (total): 6.16-7.6         Cu (total): YES
                                           Cu (dissolved): 3.2          Cu (dissolved): N/A
                                           Zn (total): 48.3-118.74      Zn (total): YES
                                           Zn (dissolved): 13.8         Zn (dissolved):

 Polycyclic             High
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal varies widely, due in part to different sizing criteria, underlying soil conditions and design features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). Refer to
BMP Selection Process document for basis of statistical analysis.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                H-5
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Large                 2-10% of drainage area. A ratio of watershed area to wetlands area of at
                                                 least two percent is recommended to have efficient removal capabilities
 Drainage Area(2)          Large                 10 to 50 acres. There must be a sufficient drainage area to maintain base
                                                 flow in the system.
 Soil Infiltration Rate(3) Low +++               Wetland site must have existing natural soil conditions that facilitate
                                                 ponding, or these conditions must be created using clay, PVC, or other
                                                 types of liners.
 Slope (gradient)(4)       Low +++               Operates at a wide range of slope with 25% maximum slope allowed.
 Groundwater level(5)      Shallow +             In general, there is no minimum separation distance required with
                                                 stormwater wetlands. Wetland site must have existing natural soil
                                                 conditions that facilitate ponding, or these conditions must be created
                                                 using clay, PVC, or other types of liners.
 Dependency on Soil        Dependent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    Low-Medium               Frequent maintenance and inspection, which usually
                                                    involves moderate costs, are critical during the
                                                    establishment of vegetation in the marsh or wetland.
                                                    Sediment removal. Vegetation removal and
                                                    replacement.
 Community                      Medium-High         Properly sited wetland systems can be scenic assets
 Acceptance(2)                                      along a highway corridor.
 Construction Cost(3)           Medium-High         Costs for ponds typically include costs for
                                                    embankment, riser and spillway structures, outfall
                                                    protection, vegetative stabilization, excavation, and
                                                    grading. Project costs can be lowered if existing pre-
                                                    construction site conditions are carefully considered
 Aquatic/Wildlife               High                Fringe wetlands and deep water habitats provide
 Habitat(4)                                         shelter and breeding places for many species.
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                             H-6
 Tool Component No. 6: Treatment Train Options
 BMP                                             Purpose                                                 Upstream Downstream
 Wetlands can provide supplementary or complementary benefits; can serve as secondary treatment from a number of BMPs.
 When combined with extended detention, wetland BMPs may be one of the most effective systems to mitigate stormwater runoff
 impacts. Sediment forebays are the commonly used pretreatment method for stormwater wetlands, although other features, such
 as grassed swales, could be used to remove sediment from runoff before it enters the wetland system.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                              X
 Storm/sanitary sewer system maintenance                                                                      X
 Proper vehicle washing and management practices                                                              X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                    X
 Limit clearing and grading of forests and native vegetation.                                                 X
 Manage a fixed portion of community open space as protected green space.                                     X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
 Minimize lane widths based on traffic volume.
 Provide stormwater treatment, wherever possible, that can be integrated into required                        X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                X
 Minimize runoff through low impact development design including pervious pavement, water                     X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                          X        X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X        X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X        X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                              X        X
 Water Quality**
  Provides pretreatment for wetland influent or additional treatment for wetland effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                               X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                        X
 Wet Ponds (additional treatment for metals, nutrients)                                                                X
 Media Filter (pretreatment for sediment, metals, nutrients)                                                  X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Hydraulic structures (reduce velocity of runoff entering the wetland)                                        X        X
 Infiltration trench/pond                                                                                              X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                          H-7
Extended Detention Dry Pond
Description

An extended detention dry pond is a basin that has been designed to detain stormwater for some
minimum time to allow particles and attached pollutants to settle, thus providing water quality
control. Extended dry ponds do not have a large permanent pool of water; instead, water that
enters the pond is released over a period of time. They typically have the following design
features:

      A low flow channel to convey flows up to the water quality design flow.
      An extended detention outlet control structure. The outlet structure can be a riser or two
       Type D outlet structures. The first Type D outlet, referred to as the water quality outlet
       structure, is sized to accommodate the water quality outflow rate. The second Type D
       outlet, referred to as the bypass outlet structure, is sized to pass at least the 10-year event.
      A sediment forebay can be used to increase the treatment efficiency of the pond and to
       dissipate energy as water flows into the pond.
      An emergency spillway sized to safely pass flows that exceed the design storm is
       optional.

Application
   Settling of particulate pollutants and suspended solids.
   Detention storage during high flow events.
   Opportunities for siting extended detention facilities are in medians, interchanges,
      adjacent to ramps, and along rights-of-way adjacent to roads.

Pollutant Removal Mechanism
    Density Separation (key treatment mechanism)
    Hydrologic Attenuation (key treatment mechanism)
    Sorption
    Filtration
    Uptake/Storage
    Microbial Transformation

Primary Targeted Pollutants
    Sediment/Particulate
    Metals (particulate)

Secondary Targeted Pollutants
    Nutrients
    Oil and Grease
    Polycyclic Aromatic Hydrocarbons (PAH)
    Metals (dissolved)




                                                                                                    I-1
Schematic Detail




                   I-2
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  Medium             Effective at removing suspended solids and
                                                   sediments. Not as effective at removing dissolved
                                                   pollutants.
 Channel Protection             High               Detains water quality flow providing some channel
                                                   protection. Controlled release rate is designed to
                                                   maintain the existing hydraulic conditions in the
                                                   downstream watercourse.
 Peak Discharge                 High               Provides water storage up to water quality event.
                                                   When coordinated with other BMPs in the watershed,
                                                   they can effectively reduce stormwater peak flows.
 Recharge                       Low                Designed to detain flow, infiltration not the primary
                                                   function.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**     Comments
 Drinking Water Protection(1) Acceptable           Minimal infiltration occurs with proper siting and
                                                   design.
 Aquatic Species               Acceptable          Provides flow duration control; however. residence
 Protection(2)                                     times that are too long may allow the water to become
                                                   heated, resulting in a potential thermal impact to
                                                   receiving waters.
 Water Quality Protection(3)   Acceptable          Nutrients, heavy metals, and other pollutants
                                                   associated with these particulates are removed.
                                                   Residence time may allow for as much as 90 percent
                                                   removal of particulates through settling
 Wetlands Protection(4)        Acceptable          A shallow marsh or wetland may be incorporated into
                                                   the design to facilitate removal of nitrogen and
                                                   phosphorus.
 Sensitive Lakes               Acceptable          Due to limited phosphorus removal
 Protection(5)
*Category Notes:
(1)
    Drinking water Protection – Applies to groundwater: Use the sensitive lakes category to define BMP design restrictions for surface water
drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                                I-3
 Tool Component No. 3: Water Quality – Effectiveness
     Parameter          Overall        Documented Removal                   Statistical Difference
                     Effectiveness      Efficiency and Effluent           Between Influent-Effluent
                        Rating(1)          Concentrations(2)                  Concentrations(3)
 Sediment/          High              Removal Efficiency:                Average influent-effluent:
 Particulate                          65-90%                             NO (NRCH) / YES (IBMPD)
 (Total suspended                     Effluent Conc.:                   Influent-effluent EMCs:
 solids)                              40.72-44.4 mg/L                   NO (NRCH) / YES (IBMPD)
 Nutrients:             Moderate           Removal Efficiency:           Average influent-effluent:
 (Nitrogen,                                TP: 20-94%                    TP: NA
 Phosphorus)                               TN: 28-50%                    TN: NA
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           TP:                          TP: NA
                                                                        TN: NA
 Hydrocarbons           Moderate           Removal Efficiency:          Average influent-effluent:
 (oil and grease)                          NA                           NA
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           NA                           NA
 Bacteria               Not                Removal Efficiency:          Average influent-effluent:
 (pathogens/E.          Applicable         NA                           NA
 Coli)                                     Effluent Conc.:              Influent-effluent EMCs:
                                           NA                           NA
 Metals                 High               Removal Efficiency:          Average influent-effluent:
 (particulate and       (particulate)      24-89% (not specified)       Cu (total): YES (NRCH) /
 dissolved)                                                             NO (IBMPD)
                        Moderate                                        Cu (dissolved): NO
                        (dissolved)                                     Zn (total): YES (NRCH) /
                                                                        NO (IBMPD)
                                                                        Zn (dissolved): NO
                                           Effluent Conc. (ug/L):       Influent-effluent EMCs:
                                           Cu (total): 18.59-22.5       Cu (total): YES
                                           Cu (dissolved): 10.98-       Cu (dissolved): NO
                                           14.72                        Zn (total): YES
                                           Zn (total): 85.26-122.5      Zn (dissolved): NO
                                           Zn (dissolved): 34.34-
                                           58

 Polycyclic             Moderate
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal varies widely, due in part to different sizing criteria, underlying soil conditions and design features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). Refer to
BMP Selection Process document for basis of statistical analysis.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                 I-4
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Large                 10 to 20 percent of drainage area. Extended detention dry
                                                 ponds require significant land area. Additional space
                                                 constraints may reduce the applicability of some pond
                                                 enhancement features such as a forebay.
 Drainage Area(2)          Large                 Maximum area typically less than 50 acres. 2 acre minimum.
                                                 Orifice size determines minimum area.
 Soil Infiltration Rate(3) Low ++                Infiltration rate not a key factor, however relatively
                                                 impermeable soils, (generally less than 0.06 inches per
                                                 hour) may create problems with standing water within the
                                                 pond.
 Slope (gradient)(4)       Medium +              Maximum slope is 25%
 Groundwater level(5)      Deep ++               Depth to groundwater is not a critical factor for siting the
                                                 facility, as long as depth to groundwater does not intercept
                                                 bottom of the pond.
 Dependency on Soil        Dependent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    Medium                   Sediment removal from fore bay required every two years,
                                                    approximately. Annual inspections are required to check for
                                                    seepage. Other routine maintenance includes reseeding of
                                                    the pond banks and bottom, removal of debris from the
                                                    spillway, and outlet cleaning.
 Community                      Moderate            Has potential for nuisance insects or odor; poses potential
 Acceptance(2)                                      safety concerns (drowning); provides more natural
                                                    setting/view; can consume large areas
 Construction Cost(3)           Moderate            Cost factors for stormwater management ponds are
                                                    extremely sensitive to site conditions. Availability of in situ
                                                    materials for embankment construction, outlet protection,
                                                    cost of excavation, liner materials, and land costs are
                                                    significant factors.
 Aquatic/Wildlife               Moderate            Provides vegetation including shrubs, trees; does not
 Habitat(4)                                         provide permanent pool of water for aquatic habitat.
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers..
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.




                                                                                                                                              I-5
**Ratings (low, moderate, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                            I-6
 Tool Component No. 6: Treatment Train Options
                                                                                                         Upstream    Downstream
 Extended detention dry ponds must be designed with a fore bay for sediment control. Implementing the measures in this table
 can, especially an energy dissipator or pretreatment facility can reduce maintenance frequency and lengthen the life of an
 extended detention dry pond. Other design approaches such as wet ponds and wetlands may be used in conjunction with
 extended detention for more efficient water quality control. A shallow marsh or wetland may be incorporated into the design to
 facilitate removal of nitrogen and phosphorus.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                              X
 Storm/sanitary sewer system maintenance                                                                      X
 Proper vehicle washing and management practices                                                              X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                    X
 Limit clearing and grading of forests and native vegetation.                                                 X
 Manage a fixed portion of community open space as protected green space.                                     X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
 Minimize lane widths based on traffic volume.                                                                X
 Provide stormwater treatment, wherever possible, that can be integrated into required                        X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                X
 Minimize runoff through low impact development design including pervious pavement, water                     X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                          X             X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X             X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X             X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                              X             X
 Water Quality**
  Provides pretreatment for extended detention dry pond influent or additional treatment for effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                               X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                        X
 Wet Ponds (additional treatment for metals, nutrients)                                                                     X
 Wetlands (additional treatment for metals, nutrients)                                                                      X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Hydraulic structures (reduce velocity of runoff entering the extended detention dry pond)                    X             X
 Infiltration trench/pond                                                                                                   X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                           I-7
Wet Pond
Description

Wet ponds are effective water quality control facilities that maintain a permanent or seasonal
pool of water often called a wet pool, pool storage or dead storage. Wet ponds are surface
facilities open to the atmosphere that rely on biological activity as well as physical and chemical
interactions to remove pollutants. They may be designed solely for water quality control (offline
configuration), with a conveyance function (inline configuration), or to provide a combined
water quality control and detention function. Typical features include:

      A wet pool cell at the inlet end of the pond (first wet pool cell).
      A wet pool at the outlet end of the pond (second wet pool cell). The second wet pool cell
       provides secondary pollutant removal.
      A berm that separates the first and second wet pools.
      Pond vegetation consistent with treatment goals.
      Inlet erosion control at the pond inlet to dissipate energy and prevent erosion.
      An outlet structure that will pass flows up to the peak flow for conveyance.
      An emergency spillway per detention facility requirements

Application
   Settling of particulate pollutants and suspended solids.
   Removal of dissolved pollutants such as soluble phosphorus and metals.
   Good areas for wet ponds are inside loop ramps and open areas upstream from natural
      drainage ways and wetlands.
   The site must be large enough to accommodate the ponds and provide sufficient setback
      distances.
   Avoid areas with steep slopes and areas without access for maintenance.
   Extended detention wet ponds (variation of standard wet pond) are cost-effective
      stormwater treatment practices for providing runoff detention storage for channel
      protection and overbank flood control.

Pollutant Removal Mechanism
    Density Separation (key treatment mechanism)
    Hydrologic Attenuation
    Sorption
    Filtration
    Uptake/Storage
    Microbial Transformation

Primary Targeted Pollutants
    Sediment/Particulate
    Metals (particulate)

Secondary Targeted Pollutants




                                                                                                J-1
   Nutrients
   Oil and Grease
   Polycyclic Aromatic Hydrocarbons (PAH)
   Metals (dissolved)




                                             J-2
Schematic Detail




                   J-3
BMP Selection Tool Input Ratings

 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                 Rating(1)           Comments
 Water Quality             Medium              Relatively effective at reducing suspended solids and
                                               phosphorus; able to effectively reduce many pollutant
                                               loads although effluent concentrations may not be as
                                               low as other BMPs.
 Channel Protection        Medium              Rating is variable depending on whether an extended
                           (Variable)          detention is provided in the wet pond to hold flow
                                               control volume.
 Peak Discharge            High                Provides peak discharge detention in wet pool.
 Recharge                  Low (to None)       Design is intended to maintain a pool; typically used
                                               in soils with low infiltration rates; impermeable liners
                                               are sometimes required to maintain pool.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category                       Applicability      Comments
 Drinking Water Protection(1)   Preferred          Lining the pond may be necessary to protect ground
                                                   water, particularly when the seasonally high ground
                                                   water elevation is within three feet of the pond
                                                   bottom.
 Aquatic Species Protection(2) Acceptable          Provides some channel protection, but tends to
                                                   increase water temperature and may cause
                                                   downstream thermal impact.
 Water Quality Protection(3)    Preferred          Most effective at removing sediments and nutrients.
 Wetlands Protection(4)         Preferred          Moderately effective at removing nutrients.
 Sensitive Lakes Protection(5) Preferred           Increased permanent pool volumes are recommended
                                                   for enhanced removal of nutrients.
*Category Notes:
(1)
    Drinking water Protection – Applies to groundwater: minimizes risk for groundwater contamination; provides aquifer recharge. Use the
sensitive lakes category to define BMP design restrictions for surface water drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3)
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                                J-4
 Tool Component No. 3: Water Quality – Effectiveness
     Parameter              Overall          Documented Removal               Statistical Difference
                         Effectiveness       Efficiency and Effluent        Between Influent-Effluent
                            Rating(1)           Concentrations(2)               Concentrations3)
 Sediment/              High                Removal Efficiency:           Average influent-effluent:
 Particulate                                80%; 50-96%                   YES
 (Total suspended                           Effluent Conc.:               Influent-effluent EMCs:
 solids)                                    19-21.5 mg/L                  YES
 Nutrients:             Moderate            Removal Efficiency:           Average influent-effluent:
 (Nitrogen,                                 TP: 40%; 20-90%               TP: YES (NRCH) / NO
 Phosphorus)                                TN: 30%; 10-90%               (IBMPD)
                                                                          TN: NO
                                            Effluent Conc.:               Influent-effluent EMCs:
                                            TP: 0.16-0.19 mg/L            TP: YES
                                            TN: 1.17-1.38 mg/L            TN: NO

 Hydrocarbons           Moderate            Removal Efficiency:          Average influent-effluent:
 (oil and grease)                           80%                          NA
                                            Effluent Conc.:              Influent-effluent EMCs:
                                            NA                           NA
 Bacteria               High                Removal Efficiency:          Average influent-effluent:
 (pathogens/E.                              60-70%                       NA
 Coli)                                      Effluent Conc.:              Influent-effluent EMCs:
                                            146 to 499 count/100         NA
                                            mL E. Coli effluent
                                            concentration
 Metals                 High                Removal Efficiency:           Average influent-effluent:
 (particulate and       (particulate)       60% (24%-89% FHWA)            Cu (total): NO
 dissolved)                                                               Cu (dissolved): NO
                        Moderate                                          Zn (total): NO
                        (dissolved)                                       Zn (dissolved): NO
                                            Effluent Conc. (ug/L):        Influent-effluent EMCs:
                                            Cu (total): 6.92-8.83         Cu (total): YES
                                            Cu (dissolved): 3.2-5.77      Cu (dissolved): YES
                                            Zn (total): 28.63-77          Zn (total): YES
                                            Zn (dissolved): 16.89-        Zn (dissolved): YES
                                            41.68
 Polycyclic             Moderate
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal varies widely, due in part to different sizing criteria, underlying soil conditions and design features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). Refer to
BMP Selection Process document for basis of statistical analysis.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                J-5
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Medium                4 to 20 percent of drainage area.
 Drainage Area(2)          Large                 10 to 50 acres needed to sustain wet pond. Ten acres
                                                 may be feasible, if ground water is intercepted and/or if
                                                 water balance calculations indicate a wet pool can be
                                                 maintained.
 Soil Infiltration Rate(3) Low +++               Infiltration rates must be low to maintain pool.
 Slope (gradient)(4)       Low +                 25 % maximum slope and 0.5 to 1% minimum slope
                                                 across location of practice to promote flows toward
                                                 pond.
 Groundwater level(5)      Deep +                No minimum separation distance required in general.
                                                 Intercepting the groundwater table can help sustain a
                                                 permanent pool. Some source water protection
                                                 requirements may require a separation distance or an
                                                 impervious liner.
 Dependency on Soil        Dependent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    Medium-High              Maintenance activities include mowing, replanting
                                                    vegetation, sediment removal (once every 5 to 15
                                                    years), pipe and riser repairs.
 Community                      Medium              Have the potential for nuisance insects or odor; poses
 Acceptance(2)                                      potential safety concerns (drowning); provides more
                                                    natural setting/view; can consume large areas
 Construction Cost(3)           Medium              Potentially large areas required for excavation (and
                                                    acquisition)
 Aquatuc/Wildlife               High                Provides vegetation including shrubs, trees, wetland
 Habitat(4)                                         plantings and surface water pond for water fowl, birds,
                                                    other mammals.
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                              J-6
 Tool Component No. 6: Treatment Train Options
 BMP                                             Purpose                                                 Upstream     Downstream
 Wet ponds are typically installed as an end-of-pipe BMP at the downstream end of the treatment train. Pond size and outflow
 regulation requirements can be significantly reduced with the use of additional upstream BMPs. Wet ponds should be designed to
 provide adequate water quality and water quantity treatment for all regulated storms if it is the only BMP employed. It is highly
 recommended that pretreatment be provided to reduce the future pond maintenance burden.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                              X
 Storm/sanitary sewer system maintenance                                                                      X
 Proper vehicle washing and management practices                                                              X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                    X
 Limit clearing and grading of forests and native vegetation.                                                 X
 Manage a fixed portion of community open space as protected green space.                                     X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
 Minimize lane widths based on traffic volume.                                                                X
 Provide stormwater treatment, wherever possible, that can be integrated into required                        X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                X
 Minimize runoff through low impact development design including pervious pavement, water                     X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                          X               X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X               X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X               X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                              X               X
 Water Quality**
  Provides pretreatment for pond influent or additional treatment for pond effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                               X
 Bioswale (pretreatment to reduce sediment, metals and nutrient loading)                                      X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                        X
 Ponds in series (additional pollutant loading removal)                                                       X               X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Hydraulic structures (reduce velocity of runoff entering the pond)                                           X
 Infiltration trench/pond                                                                                                     X
 Ponds in series                                                                                              X               X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                          J-7
Wet Vault
Description

A wet vault is an underground structure that has a permanent pool of water that dissipates energy
and improves the settling of particulate pollutants. A wet vault’s primary treatment feature is its
permanent pool for sedimentation. Because they are located underground, wet vaults lack the
biological pollutant removal mechanisms present in wet ponds.

Application
   Wet vaults are typically in-line structures that are generally used for commercial,
      industrial, or roadway projects if space is a limitation.
   System should be located in an area where maintenance and potential repairs can be
      conducted with minimal disturbance to surrounding uses.
   Primarily designed for settling of particulate pollutants and suspended solids. Ineffective
      in removing dissolved pollutants such as soluble phosphorus or metals such as copper.
   Areas where freezing temperatures occur are a concern.

Pollutant Removal Mechanism
    Density Separation

Targeted Pollutants
    Sediment/Particulate
    Oil and Grease
    Metals (particulate)




                                                                                                K-1
Schematic Detail




                   K-2
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  Low-Medium         Primarily for the settling suspended solids
 Channel Protection             High               Designed to retain the design storm runoff
 Peak Discharge                 High               Designed to retain the design storm runoff
 Recharge                       None               Lined facility or concrete structure to limit or prevent
                                                   any recharge/infiltration.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**           Comments
 Drinking Water Protection(1) Preferred                  Limited to no infiltration occurs.
 Aquatic Species               Acceptable                Provides detention and peak flow control
 Protection(2)
 Water Quality Protection(3)   Restricted                Primary water quality benefits are for particulates and
                                                         sediments.
 Wetlands Protection(4)            Restricted            Limited to no nutrient removal.
 Sensitive Lakes                   Restricted            Limited to no nutrient removal.
 Protection(5)
*Category Notes:
(1)
    Drinking water Protection – Applies to groundwater. Use the sensitive lakes category to define BMP design restrictions for surface water
drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               K-3
 Tool Component No. 3: Water Quality – Effectiveness
     Parameter          Overall        Documented Removal                   Statistical Difference
                     Effectiveness      Efficiency and Effluent           Between Influent-Effluent
                        Rating(1)          Concentrations(2)                 Concentrations(3)
 Sediment/          Moderate          Removal Efficiency:                Average influent-effluent:
 Particulate                          75 to 90 %                         NA
 (Total suspended
 solids)                              Effluent Conc.:                   Influent-effluent EMCs:
                                      90 to 45 mg/L                     NA
 Nutrients:             Not                Removal Efficiency:           Average influent-effluent:
 (Nitrogen,             Applicable         TN                            TP: NA
 Phosphorus)                               TP: : 35 to 45 %              TN:
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           TP: 0.29 to 0.15 mg/L        TP: NA
                                                                        TN: NA
 Hydrocarbons           Moderate           Removal Efficiency:          Average influent-effluent:
 (oil and grease)                                                       NA
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           NA                           NA
 Bacteria               Low                Removal Efficiency:          Average influent-effluent:
 (pathogens/E.                                                          NA
 Coli)                                     Effluent Conc.:              Influent-effluent EMCs:
                                           22,450 to 594                NA
                                           Count/100 mls
 Metals                 Moderate           Removal Efficiency:           Average influent-effluent:
 (particulate and       (particulate)      Cu (total): 35 to 45 %        Cu (total): No
 dissolved)                                Zn (total): 35 to 45 %        Cu (dissolved): No
                        Not                                              Zn (total): Yes
                        Applicable                                       Zn (dissolved): No
                        (dissolved)        Effluent Conc. (ug/L):       Influent-effluent EMCs:
                                           19.7 to 10.3                 Cu (total): Yes
                                           Cu (dissolved): 9.1 to       Cu (dissolved): No
                                           3.7                          Zn (total): Yes
                                           119 to 68                    Zn (dissolved): No
                                           Zn (dissolved): 50 to 26

 Polycyclic             Not
 Aromatic               Applicable
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal in grassed swales varies widely, due in part to different sizing criteria, underlying soil conditions and design
features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). BMP
category of “biofilter” was assumed. Refer to BMP Selection Process document for basis of statistical analysis.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                K-4
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Small                 0.5 to 1 percent of drainage area.
 Drainage Area(2)          Small                 1-10 acre maximum. Larger areas may require flow
                                                 splitters or multiple parallel facilities. Wet vaults are
                                                 most practical in relatively small catchments (less than
                                                 10 acres of impervious surface)
 Soil Infiltration Rate(3)      Not applicable      Soil infiltration rate is not a critical factor for siting the
                                +                   facility
 Slope (gradient)(4)            Not applicable      Slope is not a critical factor for siting the facility.
                                +
 Groundwater level(5)           Not applicable      Depth to groundwater is not a critical factor for siting
                                +                   the facility, vault buoyancy must be considered in
                                                    shallow groundwater applications.
 Dependency on Soil             Independent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction

 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    High                     Maintenance is usually conducted by periodically
                                                    pumping out sediments and debris. Sediment removal.
                                                    Oil removal.
 Community                      High                Generally not visible to community.
 Acceptance(2)
 Construction Cost(3)           Moderate-High       High costs associated with concrete structure
                                                    construction and excavation.
 Wildlife Habitat(4)            Low (none)          No habitat provided.
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                             K-5
 Tool Component No. 6: Treatment Train Options
 BMP                                             Purpose                                                   Upstream      Downstream
 Water quality controls, such as water quality inlets and sand filters, are often used to pretreat the stormwater before it enters the
 system. This is done to remove sediment and pollutants, which might clog the system.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                                X
 Storm/sanitary sewer system maintenance                                                                        X
 Proper vehicle washing and management practices                                                                X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                      X
 Limit clearing and grading of forests and native vegetation.                                                   X
 Manage a fixed portion of community open space as protected green space.                                       X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                    X
 Minimize lane widths based on traffic volume.                                                                  X
 Provide stormwater treatment, wherever possible, that can be integrated into required                          X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                  X
 Minimize runoff through low impact development design including pervious pavement, water                       X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                            X               X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                    X               X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls                 X               X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                                X               X
 Water Quality**
  Provides pretreatment for swale influent or additional treatment for swale effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                                 X               X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                          X
 Swale in series or parallel (provides additional capacity for larger water quality volumes)                    X               X
 Media Filter (pretreatment for sediment, metals, nutrients)                                                    X
 Water Quantity
  Provides additional volume and peak discharge reduction
 NA                                                                                                              -              -
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                          K-6
Media Filter (non-proprietary)
Description

Media filters, specifically surface filters and filter vaults, are typically two-chambered facilities
including a pretreatment settling basin and a filter bed filled with sand or other absorptive media.
Because media filters are subject to clogging and have high maintenance requirements, as well as
high construction costs, other treatment options should be carefully evaluated before selecting a
media filtration method of treatment.

      Media filters can be organized into two categories:
      Inert media filters are designed to remove suspended solids and any attached pollutants.
       The most common inert media filters include sand, perlite, and crushed glass.

      Chemically-active media filters use a filter medium that interacts with target pollutants
       such as dissolved metals, phosphorus and organics to remove them from the water phase.
       These media are often proprietary, and include leaf compost, iron-amended resin, and
       surface-modified sand.

      Common design elements for sand filters treating stormwater include the following:
      A pretreatment facility to remove suspended solids.
      A mechanism for dissipating energy at the inlet.
      A mechanism for flow spreading at the inlet to the filter.
      A sand bed that contains the filtering medium.
      An underdrain system to convey filtered stormwater to a conveyance system.

Application
   The applicability of surface sand filters to roadway projects has been demonstrated.
   Media filter designs are poorly suited to providing stormwater quantity management to
      prevent flooding because high flows can easily damage the filter bed.
   Underground media filters can be designed to treat flow conveyed by a storm drain or to
      collect flow directly from an impervious area (e.g. parking lot).
   Underground sand filter is considered to be highly applicable to the ultra-urban setting. It
      requires a small commitment of land area, provides dependable service, and is relatively
      effective at urban pollutant removal
   Because the unit is below grade, it is safe for application in public areas and is relatively
      vandal-proof. For roadside applications, it can be placed adjacent to roadways without
      imposing a safety hazard and can function satisfactorily in the area below elevated
      roadways or ramps.
   Sand filters can be located before or after detention facilities when placed offline. This is
      the preferred application approach. On-line sand filters should only be located
      downstream of detention.




                                                                                                  L-1
Pollutant Removal Mechanism
    Filtration (key treatment mechanism)
    Sorption
    Microbial Transformation

Primary Targeted Pollutants
    Sediment/Particulate
    Metals (particulate)

Secondary Targeted Pollutants
    Oil and Grease
    Polycyclic Aromatic Hydrocarbons (PAH)
    Metals (dissolved)




                                              L-2
Schematic Detail




                   L-3
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  Medium-High        Effective at removing suspended solids, less effective
                                                   at removing dissolved solids
 Channel Protection             None               Does not provide storage or infiltration to effectively
                                                   protect channels.
 Peak Discharge                 Low                Does not provide storage or infiltration to effectively
                                                   affect peak discharge.
 Recharge                       None               Does not provide recharge.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**           Comments
 Drinking Water Protection(1) Preferred                  Provides limited recharge; provides pollutant removal
 Aquatic Species               Acceptable                Provides limited detention and infiltration (dependent
 Protection(2)                                           on soil infiltration rate); neutral for temperature
                                                         benefits.
 Water Quality Protection(3)       Acceptable            Dependent on the type of impairment (water quality
                                                         parameter); effective for TSS and metals; limited
                                                         benefit for temperature.
 Wetlands Protection(4)            Restricted            Limited nutrient removal; no extended detention
                                                         periods.
 Sensitive Lakes                   Restricted            Limited nutrient (phosphorus) removal
 Protection(5)
*Category Notes:
(1)
    Drinking water Protection – Use the sensitive lakes category to define BMP design restrictions for surface water drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               L-4
 Tool Component No. 3: Water Quality – Effectiveness
     Parameter          Overall        Documented Removal                   Statistical Difference
                     Effectiveness      Efficiency and Effluent           Between Influent-Effluent
                        Rating(1)          Concentrations(2)                 Concentrations(3)
 Sediment/          High              Removal Efficiency:                Average influent-effluent:
 Particulate                          60 to 90 %                         YES
 (Total suspended                     (75% to 95% FHWA)
 solids)                              Effluent Conc.:                   Influent-effluent EMCs:
                                      25.47-42 mg/L                     NO (MRCH)/YES (IBMPD)

 Nutrients:             Low                Removal Efficiency:           Average influent-effluent:
 (Nitrogen,                                TN: 20 to 71 %                TN: N/A
 Phosphorus)                               (27% to 70% FHWA)             TP: NO
                                           TP: 0 to 80 %
                                           (27% to 80% FHWA)
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           TN:                          TN: N/A
                                           TP: 0.14-0.18 mg/L           TP: YES
 Hydrocarbons           Moderate           Removal Efficiency:          Average influent-effluent:
 (oil and grease)       (organic           (90% FHWA)                   NA
                        media)             Effluent Conc.:              Influent-effluent EMCs:
                                           NA                           NA
 Bacteria               Moderate           Removal Efficiency:          Average influent-effluent:
 (pathogens/E.          (organic           40%                          NA
 Coli)                  media)             (90% FHWA, BES)
                                           Effluent Conc.:              Influent-effluent EMCs:
                                           91 count/100mls              NA
 Metals                 High               Removal Efficiency:          Average influent-effluent:
 (particulate and       (particulate)      22 to 91 % Metals            Cu (total): YES
 dissolved)                                (unspecified - FHWA)         (NRCH)/NO (IMBPD)
                        Moderate                                        Cu (dissolved): NO
                        (dissolved)                                     Zn (total): NO
                                                                        Zn (dissolved): NO
                        (low for inert     Effluent Conc. (ug/L):       Influent-effluent EMCs:
                        media)             Cu (total): 5.7-12.54        Cu (total): YES
                                           Cu (dissolved): 3.7-         Cu (dissolved): NO
                                           10.33                        Zn (total): YES
                                           Zn (total): 15-68.85         Zn (dissolved): YES
                                           Zn (dissolved): 8.3-
                                           57.31

 Polycyclic             Moderate
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1)
    Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the
documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2)
    Reported pollutant removal in grassed swales varies widely, due in part to different sizing criteria, underlying soil conditions and design
features.
(3)
    Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). BMP
category of “biofilter” was assumed. Refer to BMP Selection Process document for basis of statistical analysis.

Data Sources:
NCHRP. 2006. Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.
Portland Bureau of Environmental Services. 2006. Effectiveness Evaluation of Best Management Practices for Stormwater Management in
Portland, Oregon.
Water Environment Research Federation. Undated. International Stormwater BMP Database. www.bmpdatabase.org




                                                                                                                                                L-5
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Low-moderate Underground - Negligible except for access.
                                                 Surface filters – 2 to 3 percent of drainage area.
                                                 Surface media filters may require a significant
                                                 commitment of land area depending on depth of filter.
 Drainage Area(2)          Low                   5 acres maximum and 0.5 to 2 acres preferred.
 Soil Infiltration Rate(3) Not applicable Media part of design. Designed to provide limited
                           +                     recharge.
 Slope (gradient)(4)       High +                Maxiumum slope of 20 %
 Groundwater level(5)      Medium ++             O ft if enclosed. A site with a seasonally high
                                                 groundwater table that does not provide at least two
                                                 feet of clearance to the bottom of a surface filter may
                                                 require special design and construction
                                                 considerations.
 Dependency on Soil        Independent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    Medium                   Frequent inspection. Media cleaning and/or
                                                    replacement
 Community                      High                Generally not visible to the community (underground)
 Acceptance(2)                                      or integrated into site design.
 Construction Cost(3)           High                High costs associated with concrete structure
                                                    construction and excavation.
 Aquatic/Wildlife               Low                 No habitat provided.
 Habitat(4)
Notes:
Factors*:
(1)
    Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2)
    Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3)
    Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4)
    Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                              L-6
 Tool Component No. 6: Treatment Train Options
                                                                                                         Upstream     Downstream
 Media filters can be located before or after detention facilities when placed offline. This is the preferred application approach.
 On-line sand filters should only be located downstream of detention. It is strongly recommended that the design be installed in an
 off-line configuration.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                              X
 Storm/sanitary sewer system maintenance                                                                      X
 Proper vehicle washing and management practices                                                              X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                    X
 Limit clearing and grading of forests and native vegetation.                                                 X
 Manage a fixed portion of community open space as protected green space.                                     X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
 Minimize lane widths based on traffic volume.                                                                X
 Provide stormwater treatment, wherever possible, that can be integrated into required                        X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                X
 Minimize runoff through low impact development design including pervious pavement, water                     X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                          X             X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X             X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X             X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                              X             X
 Water Quality**
  Provides pretreatment for swale influent or additional treatment for swale effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                               X             X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                        X
 Swale in series or parallel (provides additional capacity for larger water quality volumes)                  X             X
 Wet Ponds (additional treatment for metals, nutrients)                                                                     X
 Wetlands (additional treatment for metals, nutrients)                                                                      X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Detention facility or hydraulic structures (filter placed off-line)                                          X             X
 Detention facility (reduce flow rates entering filter placed on-line)                                                      X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
   the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in
   design, development, and construction practices in stormwater management.
**          The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual
   BMPs. Only limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness
   information provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                          L-7
Proprietary Facility
Description

A wide range of proprietary facilities can be used for stormwater treatment. Generally,
proprietary systems are more compact than many standard systems and installed underground,
making them a preferred method for treatment in many urban settings where space is limited.

      The general types of proprietary are:
      Separation facilities—coarse sediment, pollutants absorbed to sediment, oil, and
       floatables are separated from the flow and detained as water flows through the unit.
      Filtration facilities—fine sediment and attached pollutants are screened as the water
       flows through the system.
      Pre-designed wetland facilities—vegetation is used for pollutant removal.
      Catch basin inserts—devices that fit inside a catch basin to reduce pollutants, usually a
       filter type device.

Application
   Separation and filtration facilities reduce coarse and fine sediment, attached pollutants,
      oil, and other floatables. They are useful for situations with limited space.
   Pre-designed wetlands need sufficient land area and can be designed either in- or off-line
      although off-line is preferred.
   Catch basin insert reduce pollutant loads by capturing coarse sediment and attached
      pollutants.

Pollutant Removal Mechanism
    Sorption (key treatment mechanism for filtration)
    Filtration (key treatment mechanism for filtration)
    Density Separation (key treatment mechanism for separation)
    Microbial Transformation

Primary Targeted Pollutants
    Sediment/Particulate (filtration and separation)
    Metals (particulate, filtration and separation)
    Oil/Grease (separation)

Secondary Targeted Pollutants
    Oil and Grease (filtration)
    Metals (dissolved, filtration)




                                                                                             M-1
Schematic Detail




            Example illustration of manufactured sediment removal structure (Stormceptor®).




                          Example VortechsTM Stormwater Treatment System
                                        (Vortechnics, 1996)




                                                                                              M-2
BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  Medium-High        Can be included as part of a treatment train. Primarily
                                                   to remove floatables and hydrocarbons along with
                                                   sediments.
 Channel Protection             Not applicable     Typically provides minimal channel protection; focus
                                                   on water quality treatment with no detention. Can be
                                                   incorporated into the structural control in certain
                                                   situations.
 Peak Discharge                 Not applicable     Typically provides minimal peak discharge reduction;
                                                   focus on water quality treatment with no detention.
 Recharge                       Not applicable     Designed for water quality treatment and to not allow
                                                   infiltration.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.


 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**     Comments
 Drinking Water Protection(1) Preferred            Proprietary facilities are designed to maximize
                                                   treatment efficiencies with limited to no groundwater
                                                   discharge.
 Aquatic Species               Restricted          Provides no channel protection or baseflow benefits.
 Protection(2)                                     Must combine with other BMPs.
 Water Quality Protection(3)   Preferred           Proprietary facilities are designed to maximize
                                                   treatment efficiencies within small areas.
 Wetlands Protection(4)        Restricted          Typically poor nutrient removal and provides no
                                                   benefits to wetland hydrology. Must combine with
                                                   other BMPs
 Sensitive Lakes               Restricted          Typically poor nutrient removal, must combine with
 Protection(5)                                     other BMPs
*Category Notes:
(1)
    Drinking water Protection – Applies to groundwater. Use the sensitive lakes category to define BMP design restrictions for surface water
drinking supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                               M-3
Note: While there has been extensive analyses conducted on the effectiveness of standard BMPs, there is limited
independent research on the pollutant removal effectiveness of proprietary BMP technology. Most of the data for
pollutant removal effectiveness comes from the companies that design and market the facilities. For this reason,
effectiveness for proprietary facilities is not included in this BMP Summary Report. The designer should conduct additional
research and justification for applying a proprietary facility for stormwater treatment.

  Tool Component No. 3: Water Quality – Effectiveness
      Parameter           Overall          Overall           Documented Removal           Statistical Difference
                      Effectiveness    Effectiveness         Efficiency and Effluent        Between Influent-
                          Rating           Rating               Concentrations(2)                Effluent
                        Filtration(1)    Separation                                         Concentrations(3)
  Sediment/          High              High                 Removal Efficiency:          Average influent-
  Particulate                                                                            effluent:
  (Total suspended                                          Effluent Conc.:             Influent-effluent
  solids)                                                                               EMCs:

  Nutrients:            Not               Not               Removal Efficiency:          Average influent-
  (Nitrogen,            Applicable        Applicable        TN:                          effluent: TP:
  Phosphorus)                                               TP:                          TN:
                                                            Effluent Conc.:             Influent-effluent
                                                            TP:                         EMCs:
                                                                                        TP:
                                                                                        TN:
  Hydrocarbons          Moderate          High              Removal Efficiency:         Average influent-
  (oil and grease)                                                                      effluent: NA
                                                            Effluent Conc.:             Influent-effluent
                                                            NA                          EMCs:
                                                                                        NA
  Bacteria              Low               Low               Removal Efficiency:         Average influent-
  (pathogens/E.                                                                         effluent:
  Coli)                                                                                 NA
                                                            Effluent Conc.:             Influent-effluent
                                                                                        EMCs:
                                                                                        NA
  Metals                High              High              Removal Efficiency:         Average influent-
  (particulate and      (particulate)     (particulate)                                 effluent:
  dissolved)
                        High              Not
                        (dissolved)       Applicable
                                          (dissolved)       Effluent Conc. (ug/L)       Influent-effluent
                                                                                        EMCs:



  Polycyclic            Not               Not
  Aromatic              Applicable        Applicable
  Hydrocarbons
  (PAH)

(1)
   Assumed filtration removal rates are based on a chemically active filter media such as a mix of perlite, zeolite, and granular
activated carbon. Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the
BMP, as well as the documented removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations
reported in literature.




                                                                                                                                              M-4
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Low                   Facilities are typically subsurface applications.
 Drainage Area(2)          Small                 5 acres maximum; 0.2 to 5 acres preferred.
 Soil Infiltration Rate(3) Not Applicable Soil infiltration rate is not a critical factor for siting the
                           +                     facility
 Slope (gradient)(4)       Not applicable Slope is not a critical factor for siting the facility.
                           +
 Groundwater level(5)      Not applicable Depth to groundwater is not a critical factor for siting
                           +                     the facility, buoyancy must be considered in shallow
                                                 groundwater applications
 Dependency on Soil        Independent
 Characteristics(6)
Notes:
(1)
    Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.
Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2)
    Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.
Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3)
    Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.
Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4)
    Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.
Slope Rating: Low <2%; Medium <5%; High >5% slope
(5)
    Groundwater level – depth to groundwater to allow proper function of BMP
Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6)
    Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.

+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction



 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                 Comments
 Overall Maintenance(1)    High                     Systems typically require frequent maintenance.
                                                    Systems should be inspected and maintained
                                                    according to the manufacturer’s recommendations.
 Community                      High                Generally not visible to community or considered as
 Acceptance(2)                                      part of primary treatment facility.
 Construction Cost(3)           Low-Medium          Dependent on type of facility. High costs can be
                                                    associated with concrete structure construction and
                                                    excavation.
 Aquatic/Wildlife               Low (none)          No habitat provided. Predesigned wetland may provide
 Habitat(4)                                         some habitat.
Notes:
Factors*:
(1) Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors
include level of effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an
“average” of ratings provided by ODOT maintenance managers.
(2) Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in
nature.
(3) Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates
when evaluating the preferred alternative.
(4) Wildlife Habitat – provides potential habitat for wildlife.
 **Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The
rating is to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                            M-5
 Tool Component No. 6: Treatment Train Options
 BMP                                               Purpose                                                    Upstream      Downstream
 Proprietary facilities are typically installed as on-line facilities with structures to by-pass high flows. In some cases, pretreatment
 is needed to reduce litter, oil and coarse sediment loadings to the facility. When a proprietary facility is needed, space is typically
 a constraint and larger BMPs such as ponds are typically not feasible.
 Pollution Prevention*
  Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
  Many other practices (not listed) need to be coordinated with residential and municipal entities.
 Street sweeping                                                                                                   X
 Storm/sanitary sewer system maintenance                                                                           X
 Proper vehicle washing and management practices                                                                   X
 Site Design/Development*
  Employs natural processes at the source to reduce pollutant loadings.
  Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
 Preserve/restore riparian buffers with native vegetation.                                                         X
 Limit clearing and grading of forests and native vegetation.                                                      X
 Manage a fixed portion of community open space as protected green space.                                          X
 Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                       X
 Minimize lane widths based on traffic volume.                                                                     X
 Provide stormwater treatment, wherever possible, that can be integrated into required                             X
 landscaping areas and traffic islands.
 Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                     X
 Minimize runoff through low impact development design including pervious pavement, water                          X
 harvesting and green roofs (where applicable).
 Construction*
 Construction practices – vehicle tracking pads, grading, sequencing                                               X              X
 Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                       X              X
 Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls                    X              X
 Post-construction – BMP maintenance, pavement management, landscape maintenance                                   X              X
 Water Quality**
  Provides pretreatment for swale influent or additional treatment for swale effluent
  Some water quality BMPs also provide additional storage
 Oil control (increase oil/hydrocarbon removal)                                                                    X              X
 Sediment removal (pretreatment to reduce sediment and metals loading)                                             X
 Swale in series or parallel (provides additional capacity for larger water quality volumes)                       X              X
 Media Filter (pretreatment for sediment, metals, nutrients)                                                       X
 Water Quantity
  Provides additional volume and peak discharge reduction
 Hydraulic structures (reduce velocity of runoff entering the proprietary facility)                                X              X
 Infiltration trench/pond                                                                                                         X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However,
the prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in design,
development, and construction practices in stormwater management.
** The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual BMPs. Only
limited information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness information
provided in Tool Component 3 only accounts for the single BMP.




                                                                                                                                         M-6
Soil Amendment
Description

Soil amendment is a general term describing organic or inorganic additions to soil to improve
soil health or other functions such as infiltration and storage. Frequently used soil amendments
for water quality include compost, organic by-products from industries such as food processing
and paper production, or mulch and other yard debris. Areas applicable for soil amendment as a
water quality BMP can include both high and low foot traffic areas. The amount of organic
material applied depends on the end use of the area: low foot traffic areas such as roadside
swales or filter strips should be amended to a final organic concentration of 10 percent, while
areas expected to receive more foot traffic should only be amended to 5 percent organic content.

Amending soils provides many benefits that increase the treatment effectiveness of many BMPs.
The additional organic material supports vegetation growth by supplying nutrients and retaining
moisture and blankets of compost applied as a soil amendment have also been shown to inhibit
weed growth allowing the desired vegetation to take hold. The texture of the amendment,
compost in particular, readily absorbs water and once it reaches saturation slowly releases the
moisture into the native material below to infiltrate. In some areas it is possible to detain the
water quality storm with enough compost. Blankets of organic soil amendments have been
shown to be very effective at reducing erosion during and after construction, even when only 6
inches thick. Compost can also be used as berms for construction runoff treatment instead of
installing traditional silt fences.

Maintenance on amended soils depends upon its use. For compost used as a filtration blanket,
the pore spaces can fill with sediment requiring periodic removal and replacement of the
compost. Planting compost blankets with native grasses or other seed mixes can prolong the
infiltrative life of the BMP as roots provide channels to allow water to infiltrate as pore spaces in
the soil become clogged with sediment. The most crucial maintenance activity is inspection.
Each year (more frequently in case of large rainfall events) the compost should be inspected to
identify areas without compost, without vegetation, diseased vegetation, any erosion channels
through the amendment, and any ponding. These problem areas should be quickly repaired to
maintain the treatment function of the BMP.

Quality of the organic amendment is a very important concern as low-quality materials can be
contaminated with heavy metals, excess nutrients, weed seeds, excess fines (sediment), or other
undesirables that can actually contaminate stormwater. Additionally, the application of the
amendment can directly influence its treatment capacity. Compost placed for erosion prevention
should not be incorporated into the soil as it can no longer function as a barrier. On the other
hand, when woody plantings are planned for the site, incorporating the compost into the soil
provides a more natural soil structure for the vegetation. Often mulch is applied as erosion
prevention instead of additional compost for woody plantings.




                                                                                                 M-7
Application
   Generally most applicable to most structural BMPs such as filter strips, swales, wetlands,
      or Low Impact Development BMPs including infiltration basins/rain gardens or adjacent
      to porous paver walkways or driveways.
   Areas of moderate slope, 4H:1V to 1H:1V.
   Areas with no concentrated flows.
   Applicable in situations where minimal maintenance effort is desired (provided grass
      cover can be maintained all year without irrigation).
   Commonly operated as a secondary-treatment BMP located downstream of other BMPs
      to allow the treated stormwater to infiltrate instead of flowing into a typical conveyance
      system.

Pollutant Removal Mechanism
    Density Separation
    Sorption

Targeted Pollutants (Primary)
    Sediment/Particulate
    Heavy metals




                                                                                             M-8
Schematic Detail


                        Typical Compost or Biosolids Soil Amendment Cross-section

                                                                                              Mulch (for woody vegetation)

                                                                                                Compost blanket (6 inches)
            Scarify soil
             boundary
                                                                                                Subsoil




                                      Typical Incorporated Soil Amendment Cross-section




                                                                                               Blended soil and amendment


                                                                                               Subsoil


BMP Selection Tool Input Ratings
 Tool Component No. 1: Application to Stormwater Management Objectives
 Objective                      Rating(1)          Comments
 Water Quality                  High               Effective at removing suspended solids, dissolved
                                                   solids removal efficiency strongly dependent upon
                                                   amendment.
 Channel Protection             Medium             Provides some storage and infiltration to protect
                                                   channels.
 Peak Discharge                 Medium             Provides some storage and infiltration to reduce peak
                                                   discharges.
 Recharge                       Medium             Provides some storage and infiltration to provide
                                                   recharge.
Notes:
Water Quality – Objective for sites subject to water quality goals or requirements (see Tool Component 2). In almost all cases, water quality
objective is applicable. Specific water quality objectives are addressed further under Tool Component 2.
Channel Protection – Objective for sites subject to channel protection requirements to protect streams.
Peak Discharge – Objective for sites subject to flood control. In almost all cases, flood control objective is applicable.
Recharge – Objective for sites subject to a recharge requirement to infiltrate runoff.
Note: BMPs that do not address any one of the objectives should not necessarily be eliminated from consideration because they may still be
needed to meet other objectives.
(1)
    Ratings (low, medium, high) are qualitative in nature and are based on a compilation of design criteria and effectiveness factors. These rating
are to be applied in the context of comparing BMPs within the BMP selection process.




                                                                                                                                               M-9
 Tool Component No. 2: Receiving Water Application
 Category*                     Applicability**     Comments
 Drinking Water Protection(1) Acceptable           Provides limited recharge; provides pollutant
                                                   removal.
 Aquatic Species               Acceptable          Provides some detention and infiltration; neutral for
 Protection(2)                                     temperature benefits.
 Water Quality Protection(3)   Preferred           Dependent on the type of impairment (water quality
                                                   parameter); effective for TSS and metals; limited
                                                   benefit for temperature.
 Wetlands Protection(4)        Acceptable          Variable nutrient removal.
 Sensitive Lakes               Acceptable          Variable nutrient (phosphorus) removal.
 Protection(5)
*Category Notes:
(1)
    Drinking water Protection – For groundwater; use the sensitive lakes category to define BMP design restrictions for surface water drinking
supplies.
(2)
    Aquatic Species Protection – minimizes channel erosion; provides channel protection; promotes baseflow; stream temperature.
(3)
    Water Quality Protection – provides enhanced pollutant removal for TMDL/303(d) listed pollutants of concern (corresponds with Tool
Component 3).
(4)
    Wetlands Protection – maintains wetland hydroperiods and provides enhanced removal of nutrient (phosphorus) loads.
(5)
    Sensitive Lakes Protection – provides enhanced removal of nutrient loads (primarily phosphorus).

**Rating Notes:
Preferred – provides positive benefits to meet needs under receiving water category.
Acceptable – provides limited benefit or is not a detriment to receiving water category.
Restricted – Potentially detrimental to receiving water category.




                                                                                                                                           M-10
 Tool Component No. 3: Water Quality – Effectiveness
     Parameter          Overall        Documented Removal                         Statistical Difference
                     Effectiveness      Efficiency and Effluent                 Between Influent-Effluent
                        Rating(1)          Concentrations(2)                       Concentrations(3)
 Sediment/          Moderate          Removal Efficiency:                      Average influent-effluent:
 Particulate                          94%
 (Total suspended                     Effluent Conc.:                          Influent-effluent EMCs:
 solids)                              14 mg/L
 Nutrients:               Moderate(4)         Removal Efficiency:               Average influent-effluent:
 (Nitrogen,                                   TP: 84%                           TP:
 Phosphorus)                                  TN: NA                            TN:
                                              Effluent Conc.:                  Influent-effluent EMCs:
                                              TP: 0.056 mg/L                   TP:
                                              TN: NA                           TN:
 Hydrocarbons             High                Removal Efficiency:              Average influent-effluent:
 (oil and grease)                             79% (motor oil)
                                              Effluent Conc.:                  Influent-effluent EMCs:
                                              0.45 mg/L (motor oil)
 Bacteria                 Not                 Removal Efficiency:             Average influent-effluent:
 (pathogens/E.            Applicable
 Coli)                                        Effluent Conc.:                  Influent-effluent EMCs:

 Metals                   High                Removal Efficiency:              Average influent-effluent:
 (particulate and                             Cu (total): 80%
 dissolved)                                   Cu (dissolved): 4%
                                              Zn (total): 87%
                                              Zn (dissolved): 74%
                                              (WSDOT)
                                              Effluent Conc. (ug/L):           Influent-effluent EMCs:
                                              Cu (total): 8.5
                                              Cu (dissolved): 4.6
                                              Zn (total): 25
                                              Zn (dissolved): 12
                                              (WSDOT)
 Polycyclic               Moderate
 Aromatic
 Hydrocarbons
 (PAH)

Notes:
(1) Overall effectiveness rating is qualitative in nature and takes into consideration the treatment mechanisms inherent to the BMP, as well as the documented

removal efficiencies, effluent concentrations and statistical difference between influent-effluent concentrations reported in literature.
(2) Reported pollutant removal varies widely, due in part to different sizing criteria, underlying soil conditions and design features.
(3) Influent-effluent statistics are based on the statistical results compiled in the International BMP Database (www.bmpdatabase.org). Refer to BMP Selection

Process document for basis of statistical analysis.
(4)WSDOT also measured soluble reactive phosphorous, which showed an increase in concentration of 75% after contact with the compost.



Data Sources:
WSDOT, 2007. Compost-Amended Vegetated Filter Strip Performance Monitoring Project
http://www.wsdot.wa.gov/NR/rdonlyres/B4785C56-C0C2-45C6-88B9-A9912FC2E031/0/CAVFSdraft2006Report.pdf




                                                                                                                                                           M-11
 Tool Component No. 4: Physical Site Suitability
 Parameter                 Rating                Comments
 Surface Area(1)           Low                   25 percent of drainage area. In most applications, soil
                                                 amendments are placed adjacent to roadways.
                                                 Gradient, width, and length can be set based on local
                                                 constraints.
 Drainage Area(2)          Low                   Maximum recommended overland flow distance should
                                                 not be more than 75 ft for an impervious service area or
                                                 150 ft for a pervious service area.
 Soil Infiltration Rate(3) Low +                 Infiltration into soil is not a key removal mechanism for
                                                 amended soils and is generally not a constraint.
                                                 Amended soils require sheet flow across the entire
                                                 area.
 Slope (gradient)(4)       Medium ++             Longitudinal slope must be less than 5% percent,
                                                 maximum lateral slope of 1H:1V, below 3H:1V
                                                 preferred. Terracing and other soil stabilization
                                                 mechanisms can be used to overcome adverse slopes.
 Groundwater level(5)      Medium ++             Groundwater depth is not a key constraint or siting
                                                 factor for soil amendments, as long as the compost
                                                 layer is not submerged. Typically 3 ft to groundwater
                                                 is acceptable.
 Dependency on Soil        Dependent +           Application of soil amendment can improve poor soil
 Characteristics(6)                              conditions from texture/infiltration rate to chemical
                                                 activity.
Notes:
(1) Surface Area – size of surface area BMP requires in terms of percentage total contributing surface area.

Surface Area Rating: Low <5%; Medium <10%, Large >10% of impervious area
(2) Drainage Area – size of drainage area generally applicable for the “conventional” application of the BMP.

Drainage Area Rating: Small < 2 acres; Medium <10 acres, Large >10 acres of drainage area
(3) Soil Infiltration Rate – preferred soil infiltration rates for optimum BMP performance.

Soil Infiltration Rate Rating: Low < 0.5 in/hr; Medium <2.5 in/hr; High >2.5 in/hr
(4) Slope (gradient) – preferred site slopes/topography to construct BMP and allow proper function.

Slope Rating: Low <2%; Medium <5%; High >5% slope
(5) Groundwater level – depth to groundwater to allow proper function of BMP

Groundwater Level Rating: Shallow <3 ft below ground surface; Medium <10 ft bgs; Deep >10 feet bgs
(6) Dependency on Soil Characteristics – Dependency as it relates to maintaining treatment effectiveness.



+++ - Will or may preclude the application of this type of facility
++ - Can generally be overcome with appropriate site design
+ - Generally not a restriction

 Tool Component No. 5: Non-Design Factors
 Factor*                   Rating**                         Comments
 Overall Maintenance(1)    Low                              Periodic maintenance for soil amendments is primarily
                                                            focused maintaining vegetation, preventing the
                                                            formation of rills and gullies, and removing debris and
                                                            litter.
 Community                           Medium                 Add an aesthetic value to roadside areas as long as
 Acceptance(2)                                              they are maintained and litter and debris are regularly
                                                            removed.
 Construction Cost(3)                Low                    Soil amendments are low-cost BMPs. The principal
                                                            cost to install is related to earth moving construction
                                                            costs and planting costs (if applicable).
 Aquatic/Wildlife                    Low                    If vegetated, area comprised primarily of grass and
 Habitat(4)                                                 provide poor wildlife habitat; no exposed surface water
                                                            for aquatic habitat.
Notes:
Factors*:
(1) Maintenance – level of effort/cost to conduct necessary inspection and maintenance through the life cycle of the BMP. Maintenance factors include level of

effort; frequency of maintenance, reliability/durability, need for specialized equipment, and O&M cost. The rating shown is an “average” of ratings provided by
ODOT maintenance managers.
(2) Community acceptance – accounts for general sense of visual preference, reported nuisance problems, vegetative management; subjective in nature.
(3) Construction Cost – general cost rating to construct the BMP. Rating should not preclude preparing design-level engineering cost estimates when evaluating

the preferred alternative.



                                                                                                                                                           M-12
  Wildlife Habitat – provides potential habitat for wildlife.
(4)

**Ratings (low, medium, high) are qualitative in nature and are based on a compilation of information from references on these factors. The rating is to be
applied in the context of comparing BMPs within the BMP selection process.



      Tool Component No. 6: Treatment Train Options
                                                                                                          Upstream     Downstream
  Soil amendments can provide supplementary or complementary benefits. Soil amendments are commonly operated as a pre-
  treatment BMP located upstream of other BMPs capable of greater pollutant removal rates or as an additive to a BMP such as a
  swale or filter strip. Pretreatment is not considered crucial to the removal performance of soil amendments unless there is
  sufficient loading of pollutants (e.g., sand, oil and grease).
  Pollution Prevention*
   Reduces loadings of pollutants entering the project site limits and influent concentration in runoff.
   Many other practices (not listed) need to be coordinated with residential and municipal entities.
  Street sweeping                                                                                              X
  Storm/sanitary sewer system maintenance                                                                      X
  Proper vehicle washing and management practices                                                              X
  Site Design/Development*
   Employs natural processes at the source to reduce pollutant loadings.
   Control/minimize runoff at the source by maximizing infiltration, evapotranspiration and filtration.
  Preserve/restore riparian buffers with native vegetation.                                                    X
  Limit clearing and grading of forests and native vegetation.                                                 X
  Manage a fixed portion of community open space as protected green space.                                     X
  Prevent the discharge of unmanaged stormwater from new stormwater outfalls.                                  X
  Minimize lane widths based on traffic volume.                                                                X
  Provide stormwater treatment, wherever possible, that can be integrated into required                        X
  landscaping areas and traffic islands.
  Use vegetated open channels in the street right-of-way to convey and treat stormwater runoff.                X
  Minimize runoff through low impact development design including pervious pavement, water                     X
  harvesting and green roofs (where applicable).
  Construction*
  Construction practices – vehicle tracking pads, grading, sequencing                                          X              X
  Sediment control – silt fences, inlet protection, temporary sedimentation traps, check dams                  X              X
  Soil erosion control – mulch, blankets, mats, temporary seeding structural/vegetative controls               X              X
  Post-construction – BMP maintenance, pavement management, landscape maintenance                              X              X
  Water Quality**
   Conveys and provides pretreatment for amended BMP
  Swale (additional treatment for metals, nutrients)                                                           X
  Filter strip (additional treatment for metals, nutrients)                                                    X
  Water Quantity
   Provides additional volume and peak discharge reduction
  Hydraulic structures (reduce velocity of runoff entering the amended soil)                                   X
Notes:
* The focus of the BMP Selection Process is on selecting on-site, structural BMPs that address runoff generated from a project site. However, the
   prevention/minimization BMPs are included in Tool Component 6 to emphasize the importance of integrating low impact concepts in design, development,
   and construction practices in stormwater management.
** The BMPs provide improved water quality benefits; however, effectiveness information currently available focuses on individual BMPs. Only limited
   information is available for the overall improvement in effectiveness using these treatment train options. Effectiveness information provided in Tool
   Component 3 only accounts for the single BMP.




                                                                                                                                                              M-13

				
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