Storm Drain Flushing

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					                                                                                  SOURCE CONTROLS




Storm Drain Flushing
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: A storm drain is “flushed” with water to suspend and remove deposited materials.

Related SWMPs: Sewer system maintenance; catch basin cleaning; street cleaning.

Description: Locate reaches of storm drain with deposit
problems and develop a flushing schedule that keeps the
pipe clear of excessive build-up. In some instances it
may be necessary to acquire the existing conditions data
with “closed circuit television” (CCTV) inspection.
Flushing helps ensure pipes convey design flow and
removes pollutants from the storm drain. Whenever
possible, flushed effluent should be collected and
pumped to the sanitary sewer for treatment.
Flushing is particularly beneficial for storm drains with
grades too flat to be self-cleansing, and is most effective
in small diameter pipes.

Application Requirements: Minimum of two-persons
are needed for routine sediment removal and flush water
collection. Equipment operators are also required.
                                                           Flushing of storm drain with water to
Equipment needed:                                                 remove deposit problems
   · Water source (water truck, fire hydrant).
   · Sediment collector (vacuum truck, dredge).
   · Inflatable devices to block flow.
   · Sediment/turbidity containment/treatment equipment required if flushing to an open channel.
Proven Effectiveness/Experience Elsewhere: XCG Consultants (1999) recommended a program of
sewer flushing to reduce bacterial pollution loads to the Bay of Quinte in a recent pollution control
planning study.

Cost Considerations: Unless flushing to a dry/wet detention area, the collection of liquid and sediments
maybe costly in terms of pollutant removal benefits.




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Objectives Addressed:

                          Technical Objectives (Terms of Ref.)                           Measure
                                                                                         Addresses
 1. Achieve healthy aquatic communities                                                     X
 2. Reduce fish consumption advisories                                                      X
 3. Reduce erosion impacts
 4. Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source          X
 7. Achieve water and sediment objectives in watercourses and waterfront                    X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                     X
 10. Eliminate aesthetic nuisances                                                          X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· Can be done on an area - wide basis. Effectiveness is greatly dependent upon pipe system. Some
   systems will have little deposition depending upon flow velocities and areas drained.
References:
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993.
· XCG Consultants.1998. City of Trenton Pollution Control Planning Study - Phase 2 - Final Report.
   Report prepared for Quinte Conservation, the City of Trenton and Environment Canada Great Lakes
   2000 Cleanup Fund.




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Catch Basin Cleaning
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Catch basin and stormwater inlet
maintenance is done on a regular basis to remove
pollutants, reduce high pollutant concentrations during the
first flush of storms, prevent clogging of the downstream
conveyance system and restore the catch basin’s sediment-
trapping capacity.
The maintenance program can reduce solid loadings to
surface water and associated pollutants.
Related SWMPs: Sewer system maintenance; street
sweeping; sewer flushing.

Description: Municipal staff should inspect public and
                                                                Vacuum truck and equipment for catch
private facilities on an annual basis to ensure compliance
                                                                          basin cleaning
with the following:
·   Catch basins should be cleaned regularly enough to reduce the possibility of sediment and pollutant
    loading from the flushing effect of stormwater inflow. Cleaning should occur before the sump is 40%
    full.
·   Prioritize maintenance to clean catch basins and inlets in areas with the highest pollutant loading and
    in areas near sensitive water bodies. Ideally works should be scheduled just prior to the wet fall
    season to remove sediments and debris accumulated during the summer.
·   Keep accurate operation logs of which catch basins were cleaned and how much waste was removed
    to track program.
·   Catchbasins with “goss traps” also capture oil and other floatable materials.
·   The metal content of decant and solids cleaned from a catch basin should be periodically tested to
    determine if the decant violates limits for disposal to the wastewater treatment plant or if the solids
    would be classified as a hazardous waste.
Application Requirements: Two-person teams are required to clean catch basins with vacuum trucks.
Crews must be trained in proper maintenance, including record keeping, disposal and safety precautions.
Arrangements must be made for the proper disposal of the collected wastes.
Equipment needed: Truck mounted vacuum excavators are normally used for this activity.

Proven Effectiveness/Experience Elsewhere: N/A
Cost Considerations: An aggressive catch basin cleaning program could require a significant capital and
operating and maintenance budget because of the typically large number of catch basins in any given area
and the high cost of labour and equipment required to do the work. Smaller municipalities may elect to
contract this work out as an annual contract.




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Objectives Addressed:

                         Technical Objectives (Terms of Ref.)                            Measure
                                                                                         Addresses
 1. Achieve healthy aquatic communities                                                     X
 2. Reduce fish consumption advisories                                                      X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source          X
 7. Achieve water and sediment objectives in watercourses and waterfront                    X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                     X
 10. Eliminate aesthetic nuisances                                                          X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· Can be done on an area - wide basis. Effectiveness will depend upon drainage source and frequency
   of cleaning.

References:
· Public Works Practices, Robert Pitt, University of Alabama at Birmingham, March 30, 1998
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993.
· Butler, D. and S.H.P.G. Karunaratne. “The suspended solids trap efficiency of the roadside gully
   pot.” Wat. Res. Vol. 29, No. 2. pp. 719-729. 1995.
· Pitt, R. and G. Shawley. A Demonstration of Non-Point Source Pollution Management on Castro
   Valley Creek. Alameda County Flood Control and Water Conservation District (Hayward, CA) for
   the Nationwide Urban Runoff Program, U.S. Environmental Protection Agency, Water Planning
   Division, Washington, D.C., June 1982.




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Street Cleaning
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls.

Primary Mechanism: Some reduction in the buildup
of pollutants on street surfaces can be accomplished
by conducting street cleaning on a regular basis. The
primary and historical role of street cleaning is for
sediment and litter control.
Related SWMPs: Road maintenance; catch basin
cleaning; sewer flushing.

Description: The following approaches may be
effective in implementing and maintaining the street
cleaning BMP:
·   Prioritize cleaning to use the most technically
    advanced sweepers, at the greatest possible                        Street sweeper
    frequency, in areas with the highest pollutant
    loading.
·   Cleaning frequency should be based upon inter-event times (the dry period between storms). To
    achieve 30% removal of street dirt, the sweeping interval must be no more than 2 times the average
    interval between storms. To reach 50% removal, sweeping must occur 1 or 2 times during the average
    interval between storms.
·   Sweeping frequency should be increased just before the rainy season.
·   Proper maintenance and operation of sweepers greatly increases their efficiency.
·   Accurate operation logs should be kept of curb miles swept and amount of waste collected to track
    program.
·   Climate, parked cars, street and curb conditions, traffic congestion, and construction projects may
    limit the effectiveness of this measure.
Application Requirements: The following considerations may apply to this measure:
·   Sweeper operators and maintenance staff, supervisory and administrative personnel are required.
·   Traffic control / bylaw officers may be required to enforce parking restrictions.
·   Cleaning routes and the associated timings must be designed to optimize efficiencies.
·   Collected wastes must be properly disposed.
·   Operators require training in proper sweeper operation and technique.

Equipment needed:
Mechanical broom sweepers (more effective at picking up large debris and cleaning wet streets, less
costly to purchase but generate more dust).
Vacuum sweepers (more effective at removing fine particles and associated heavy metals but ineffective
at cleaning wet streets), combination sweepers and street flushers. Speeds of 10-15 km per hour are
optimal. In addition, brush adjustment, rotation rate and sweeping pattern also affect removal efficiencies.
Proven Effectiveness/Experience Elsewhere: Normal street cleaning operations for aesthetics and
traffic safety purposes are not very satisfactory from a stormwater quality perspective. These objectives
are different and the removal efficiency for fine and highly polluted particles is very low. Unless the street



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cleaning operations can remove the fine particles, they will always be limited in their pollutant removal
effectiveness.

Some efficient machines are now available to clean porous pavements and infiltration structures, and new
tandem machines that incorporate both brooms and vacuums have recently been shown to be very
efficient, even for the smaller particles. Conventional street cleaning operations preferentially remove the
largest particles, while rain preferentially removes the smallest particles. In addition, street cleaners are
very inefficient when the street dirt loadings are low, when the street texture is course, and when parked
cars interfere. However, it should also be noted that streets are not the major source of stormwater
pollutants for all rains in all areas.

Streets are the major source of pollutants for the smallest rains, but other areas contribute significant
pollutants for moderate and large rains. Therefore, the ability of street cleaning to improve runoff quality
is dependent on many issues, including the local rain patterns and other sources of runoff pollutants. More
research is needed to investigate newer pavement cleaning technologies in areas such as industrial storage
areas and commercial parking areas, which are critical pollutant sources.

A study in Severn Sound found that uses of the same technologies are an efficient and cost effective
stormwater management practice. Potential phosphorus reductions from stormwater of approximately 5%
are achievable at less cost than most other traditional stormwater management practices.
Cost Considerations: A street cleaning program requires a significant capital and operating maintenance
budget.

Objectives Addressed:

                           Technical Objectives (Terms of Ref.)                                 Measure
                                                                                                Addresses
 1. Achieve healthy aquatic communities                                                            X
 2. Reduce fish consumption advisories                                                             X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                   X
 7. Achieve water and sediment objectives in watercourses and waterfront                             X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                              X
 10. Eliminate aesthetic nuisances                                                                   X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· Can be done on an area – wide basis and can be evaluated on an area basis. Effectiveness depends on
   frequency of sweeping and type of equipment used.




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References:
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993.
· Public Works Practices, Robert Pitt, University of Alabama at Birmingham, March 30, 1998.
· Aaron Mattson, Severn Sound Remedial Action Plan, Urban Stormwater Management Strategy:
   Phase II- October, 1998.




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Control of Road De-Icers
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls.

Primary Mechanism: The goal of a winter operations
program is to provide safe road conditions without losing
sight of the cost implications and potential negative impacts
to the environment due to misuse of chemicals, including
road salt and other de-icing compounds.
Determine techniques to be included in anti-icing program
such as Automatic Spreaders vs. Manual Controls to
eliminate over and under spreading, especially when truck
speed is variable. Manual systems can be monitored and
adjusted by the operator based upon truck speed, but such
adjustments become a full-time job.
                                                                      Salt dome and salt truck
There are some advantages to the use of liquids at
pavement temperatures above -5°C. Prewetting of solid salt has been proven to keep more material on
the road surface as opposed to being blown away by passing vehicles. Prewetting salt quickens its melting
action and if prewetted with liquid calcium chloride, enhances its melting effect at lower temperatures.
Reductions in dry salt, which could be attributed to the effectiveness of prewetting with 32% liquid
calcium at a rate of 4 to 8% by weight, ranged from 10 to 40%.
Related SWMPs: N/A

Description: Past practices for winter road maintenance on local residential streets included waiting until
25mm or more of snow accumulated before beginning to plow and treating with chemicals which
frequently lead to the development of “pack”. Removal of this compacted layer tightly bonded to the
pavement is called de-icing. This technique usually requires a large quantity of chemical to work through
the pack to reach the snow/pavement interface and break it up. Arterial and collector streets receive
application of salt at an earlier stage of snowfall, often at the onset of snow, in order to maintain traffic
safety.
Alternatively anti-icing provides for the application of liquid chemicals on the dry pavement to prolong
the period of time during a snowfall or temperature drop until such time as ice starts to form. A recent
review of road salts by Environment Canada (Priority Substances List Assessment Report – Road Salts,
Environment Canada, August, 2000) has recommended that “road salts” primarily sodium chloride, be
considered “toxic” under Section 64 of the Canadian Environmental Protection Act 1999. This will place
salting under increasing scrutiny and increase the need for close management of operational practices.

Application Requirements: The extent to which maintenance services will be provided to a road section
must be determined and by municipal council or the jurisdictional body responsible for the road.
The Ministry of Environment Guideline B-4 Snow Disposal and De-Icing Operations in Ontario is
provided to minimize the environmental impact of snow collection and disposal practices and de-icing
operations. The Ministry encourages the sensible and conservative use of sodium chloride and other de-
icing compounds and recommends the following operational guidelines to be used by the road
maintenance agencies.




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a) Reduce de-icing chemical application rates to the minimum amount necessary to successfully perform
   the job. Experience has shown that an application rate in the order of 100 to 130 kg per km of 2 lane
   road is sufficient;
b) Employ rate-controlled distribution equipment that applies de-icing chemicals at the proper rate
   regardless of vehicle speed;
c) Apply de-icing chemicals on main thoroughfares and critical sections of roadways only;
d) Where salt/sand mixtures are applied, incorporate into the admixture only enough salt to achieve
   desired results; and
e) Consider special protective measures when de-icing chemicals are applied to places in proximity to
   very salt-sensitive areas (e.g., orchards, parks).
Proven Effectiveness/Experience Elsewhere: The City of Waterloo Salt Reduction Program resulted in
less salt use through use of more effective control of the salt dosage systems in the salt spreader trucks.
The City of Toronto reviewed practices and alternatives to road salt in the early 1990s. Changing the
plowing practices to favor more plowing and less salt application reduced salt usage.

Cost Considerations: Costing is variable, depending on the equipment and materials used; the labour and
machines needed; climate and road conditions.

Objectives Addressed:

                            Technical Objectives (Terms of Ref.)                                Measure
                                                                                                Addresses
  1. Achieve healthy aquatic communities                                                           X
  2. Reduce fish consumption advisories                                                            X
  3. Reduce erosion impacts
  4 Re-establish natural hydrologic process
  5. Re-establish natural features
  6. Virtual elimination of toxic contaminants using pollution prevention at source                     X
  7. Achieve water and sediment objectives in watercourses and waterfront                               X
  8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
  9. Improve body contact recreation in rivers and reduce beach closures
  10. Eliminate aesthetic nuisances
  11. Reduce basement flooding
  12. Reduce sanitary sewer inflow and infiltration
  13. Protect life and property from flooding

Opportunities Considerations:
· Very time dependent. Can be done on an area basis depending upon de-icing need.

References:
· Priority Substances List Assessment Report – Road Salts, Environment Canada, August 2000.
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993.




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Control of Fertilizers and Pesticides
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls.

Primary Mechanism: The reduced use of fertilizers and pesticides
can be promoted through the use of Plant Health Care Programs. These
can be designed for municipal, commercial and residential uses. By
consistently employing a particular organic set of horticultural
practices, healthy turf growth can be encouraged while having the
smallest possible environmental impact. Shrubs, trees, flowers and
walkways can be used as attractive replacements for the traditional
lawn.
An integrated Pest Management Program can include using biological
controls using “beneficial” insects as alternatives to pesticides (e.g.,
ladybird beetles, preying mantis) as well as “companion plantings” to
discourage insects.
                                                                           Pesticide free lawn care
A chemical reduction program need not advocate a complete ban on
pesticide use, but can recognize that there may be occasions when spraying may be necessary.

Related SWMPs: Integrated pest management.

Description: Naturescaping promotes natural lawn care techniques and encourages lawn replacement
with alternatives, including drought-tolerant plants. Many alternatives are available for pest and weed
control, including the use of beneficial insects, companion plantings and alternative spray compounds,
such as soap and other more environmentally friendly substances. Public education will be needed to
produce support for chemical reduction in parks and public use areas.
Public education programs can also promote reduced horticultural chemical use around residences. This
may include media publicity, educational material, e.g., brochures, lawn signs, park display areas with
interpretive signage, and community promotional events (Waterloo Dandelion Festival). Some
neighbourhood groups or individuals may be strongly opposed to the program because of their aesthetic
preferences for traditional lawns, and because of perceived health and safety risks.
Application Requirements: Xeriscaping can be defined as “quality landscaping that conserves water and
protects the environment”. Seven principles are applied: 1) planning and design, 2) soil analysis, 3)
appropriate plant selection, 4) practical turf areas, 5) efficient irrigation, 6) use of mulch, and 7)
appropriate maintenance.
A Plant Health Care Program requires a commitment to reducing pesticide and fertilizer use on a long-
term basis involving some degree of planning. Education and training of municipal workers may be
necessary, and some acceptance of possibly different aesthetics on the part of the public may have to be
solicited.
Proven Effectiveness/Experience Elsewhere: Innovative Turf Management is a Plant Health Care
Program implemented by the City of Waterloo gradually over many years. The program has successfully
reduced pesticide application from 73% of the City’s total land area in 1979 to 0.5% today.
Hudson’s By-law is a by-law banning pesticide use, which was introduced by the Town of Hudson,
Quebec in 1991. In December of 2000 the Supreme Court of Canada began hearing arguments from two



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pesticide companies on whether a municipality can enact by-laws controlling pesticide use. As of June
2001, the Supreme Court of Canada ruled that the Town of Hudson has the right to prohibit pesticide use.
A similar by-law was past last year in Halifax, while Calgary, Vancouver and Toronto are considering
such by-laws of their own. In Halifax, the ban only applies to spraying within 50 metres of schools and
hospitals, however, by April 2003, the ban will be city-wide.
Cost Considerations: Initially, landscape changes can be labour intensive, but this may be offset by
reduced costs when naturalized areas and alternative plantings are fully established. Healthy vigorous turf
is less susceptible to pest invasion; water use is reduced; there is less turf watering and maintenance costs
are often reduced.

Objectives Addressed:

                           Technical Objectives (Terms of Ref.)                                 Measure
                                                                                                Addresses
 1. Achieve healthy aquatic communities                                                            X
 2. Reduce fish consumption advisories                                                             X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                      X
 7. Achieve water and sediment objectives in watercourses and waterfront                                X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                                 X
 10. Eliminate aesthetic nuisances                                                                      X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· Area – wide measure but very dependent upon current applications. Programs in Toronto will be
   reviewed.

References:
· Alternatives to Pesticides is a publication available courtesy of the City of Cambridge, City Green
   Cambridge and Health Canada.
· Naturescaping is a brochure offering alternatives to the traditional lawn including a list of plants
   suitable for southern Ontario and is available from the Region of Waterloo by calling (519) 575-4423.
· Xeriscape Landscaping- Preventing Pollution and Using Resources Efficiently, EPA-840-B-93-001,
   April 1993.
· How to Get Your Garden off Drugs. Friends of the Earth, 701-251 Laurier Avenue West, Ottawa,
   Ontario, K1P 5J6. (613) 230-3352.
· Hudson’s Bay By-law and related topics, www.cbc.ca




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Enforcement of Anti-Litter and
Discharge By-Law
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls.

Primary Mechanism: Municipalities may pass bylaws for the maintenance
and management of its sewers, sewer system, sewage works, treatment works
and watercourses, and regulate the manner, extent and nature of the reception
and disposal of sewage and land drainage. This power is granted in Section
210 paragraph 147 of the Municipal Act.
Individuals discard litter, usually consisting of packaging material, over the
urban landscape. Pet feces are deposited primarily by dogs and left
uncollected by owners. Both types of litter end up in storm drainage and
cause problems.

Control programs involve changing individual’s behavior by preventing the
littering action. Bylaws making the littering illegal, supported by
enforcement, are the “backbone” of the prevention programs.
                                                                                 Pet litter bylaws to
Related SWMPs: Pollution prevention and control, street sweeping; catch            control animal
basin cleaning; yellow fish road program
                                                                                         waste
Description: Except where regulated by a Certificate of Approval or Order
relating to the premise under the Environmental Protection Act or Ontario Water Resources Act, which
expressly allows the discharge, typical sewer use bylaws in municipalities include the following:
·   Water at an elevated temperature i.e. greater than 40oC;
·   Water having a pH less than 6.0 or greater than 9.0;
·   Water containing an excessive amount of solids i.e. more than 15 milligrams per litre of suspended
    solids;
·   Water containing dyes or colouring materials that discolour the water;
·   Vegetable or animal matter;
·   Sewage;
·   Once-through cooling water;
·   Automotive or machine oils and greases;
·   Fuels;
·   Paints and organic solvents;
·   PCBs;
·   Pesticides;
·   Toxic Materials;
·   Hazardous Wastes;
·   Waste disposal leachate;
·   Waste radioactive materials.

Programs such as the community-based Yellow Fish Road storm drain-stenciling project can discourage
illegal dumping of household materials down street drains.




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Introduction of Stoop and Scoop and Anti-Litter bylaws should be accompanied by both a public
education program and enforcement arrangements. Public education can include media promotion, Stoop
and Scoop signing, distribution of “doggie” collection bags in parks, and through business sponsors such
as veterinarians and pet stores.
Application Requirements: Requires technical staff to detect and investigate violations and to
coordinate public education programs.
Legal staff is required to pursue prosecution of significant cases.
Administrative staff is required to maintain and update a database of all industrial sewer discharges.
Equipment needed can include:
· Personal protective equipment;
· Sampling containers and equipment;
· Laboratory facilities in house or under contract;
· Promotion and signage of the applicable By-law and appropriate enforcement.
Proven Effectiveness/Experience Elsewhere: The City of St. Catharines enforced a Stoop and Scoop
program as part of their beach improvement programs. This involved extensive public education and
surveys, signage, provision of bag dispensers and bags for dog feces.

Cost Considerations: Program costs for procuring necessary equipment and training are borne by the
industries or commercial operations responsible for the illegal discharges. Staff support is needed for
enforcement activities, legal pursuit and database compilation.

The municipality is the driving force in Anti-Litter programs with support arrangements to pick up and
dispose of lawn and garden wastes, maintenance of catch basins and street sweeping programs, litter
control through signage, provision and emptying of litter containers, and bylaw enforcement.
Bylaw officers are required to provide enforcement where necessary. Summer students or part time staff
may be used to carry out some public education programs for the Anti-Litter and Stoop and Scoop By-
laws. The cost of promotional materials will vary according to the type used and method of distribution.
Objectives Addressed:

                          Technical Objectives (Terms of Ref.)                                  Measure
                                                                                                Addresses
 1. Achieve healthy aquatic communities                                                            X
 2. Reduce fish consumption advisories                                                             X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                      X
 7. Achieve water and sediment objectives in watercourses and waterfront                                X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                                 X
 10. Eliminate aesthetic nuisances                                                                      X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· By-laws in use in the City of Toronto will be reviewed along with the program to manage and enforce
   them.


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References:
· Model Sewer Use Bylaw, MOE, 1998.
· WPCF Manual of Practice No. SM-7, 1988, Municipal Strategies for the Regulation of Sewer Use
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993.




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Water Conservation
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Water conservation and water efficiency programs
are used to reduce the volume of household and industrial water entering
combined and sanitary sewers and wastewater treatment plants. This lowers
the risk of combined sewer overflows during rainy weather and improves
the operating efficiency and long-term performance of wastewater
treatment facilities and septic tanks. Water conservation programs also
reduce the demand on groundwater resources especially in dryer seasons
and provide a cost-saving benefit for industries and other
large volume users.

Related SWMPs: Pollution prevention and control; plant
health care programs; naturalization and xeriscaping; rain
barrel program.
                                                                  Low flow showerheads and low flush
Description: Public outreach and education is the most          toilets can be installed to conserve water
significant component of a water conservation program.
This can range from providing information with utility bills to a major social marketing program to reach
a specific reduction target. Other approaches include:
·   Integrate efforts with naturalization and pesticide reduction programs for public lands;
·   Integrate water efficiency planning into municipal water supply and wastewater treatment strategies;
·   Use social marketing or educational programs for householders, businesses and industries to change
    water use habits and attitudes;
·   Produce and distribute water conservation educational brochures and printed information;
·   Develop media contacts, press releases and promotional events to promote water conservation;
·   Integrate public outreach programs or publication development with agencies or organizations with a
    compatible agenda.
·   Develop incentive programs to facilitate the installation of residential low flush toilets and water
    saving devices;
·   Use metering and water pricing strategies to provide a cost saving incentive for the end user;
·   Reduce operational water use on public parks and municipal lands;
·   Promote alternative landscaping or gardening practices which reduce the need for summer peak
    watering;
·   Develop industrial and commercial information materials, workshops and water audit kits to promote
    water efficiency in the workplace;
·   Develop school programs and provide materials such as shower timers and small water saving
    devices. Incorporate a monitoring component as assigned homework.
·   Reduce water leaks where possible.
·   Consider on-site water reuse as a means of conserving water.
Application Requirements: A staff person is needed to track, review and provide coordination of efforts.
The type of water conservation program undertaken and the level of integration with related program
services will determine other support.
Equipment needed: Municipal water use reduction may include the retrofitting or changing of public
toilets, drinking fountains and other facilities. Homeowner programs may include toilet replacement



                                                                                    City of Toronto   1 - 15
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incentives. Industrial programs may require redesign of some operations and changes to existing facilities.

Proven Effectiveness/Experience Elsewhere: A Master Plan for Water Efficiency is a large component
of the Water Resources Protection Strategy for the Regional Municipality of Waterloo (see Case Studies
for more details). The Master Plan sets water reduction targets for the next ten years and determines what
programs will be carried out to achieve these. To date the Region has facilitated the retrofitting of 7,000
low flush toilets per year through a $50 per toilet rebate incentive. Other programs include Industrial
Water Audit kits and assistance, publication materials, school programs and public information displays.
A total budget of $520,000 has been allocated for the next five years for the Water Efficiency Program.
Preliminary data from an American Water Works Association Research Foundation end user study shows
that toilets are the heaviest year round residential water users. Water softeners are also large water uses.
·   The Watershed Infrastructure Ecology Program (WIEP) in Toronto included the “5 Things You Can
    Do” program framework.
·   The City of Toronto Go Low Flow program incorporated water conservation retrofit devices. The cost
    for a basic kit of several small devices for public distribution is approximately $10.15 per kit.

The conservation co-op is a 4 storey 84 unit apartment building complex located in the Sandy Hill district
of the City of Ottawa. Tenants are committed to providing a green alternative. All members are trying to
reach goals to reduce energy, water and waste consumption, and to demonstrate that it is economically
feasible. The system demonstrates the effectiveness of light greywater reclamation and water reuse in
reducing water demand and wastewater discharge.

In Sooke, British Columbia, the Ministry of Social Services Building is a 920 square metre office
complex, housing 20 full time employees. All greywater and blackwater is treated and recycled for toilet
flushing. This system has been found to reduce wasterwater flows by 90%.
Cost Considerations: The cost of public outreach programs will be determined by the type of outreach
undertaken, the level of integration with other programs and the amount of volunteer help available.
Water conservation can be incorporated into municipal operational policies and should result in long term
cost savings.




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                                                                                   SOURCE CONTROLS



Objectives Addressed:

                         Technical Objectives (Terms of Ref.)                               Measure
                                                                                            Addresses
 1. Achieve healthy aquatic communities                                                        X
 2. Reduce fish consumption advisories
 3. Reduce erosion impacts                                                                           X
 4 Re-establish natural hydrologic process                                                           X
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                   X
 7. Achieve water and sediment objectives in watercourses and waterfront                             X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                              X
 10. Eliminate aesthetic nuisances
 11. Reduce basement flooding                                                                        X
 12. Reduce sanitary sewer inflow and infiltration                                                   X
 13. Protect life and property from flooding                                                         X

Opportunities Considerations:
· The City of Toronto is developing a new strategy for water conservation. This will be reviewed.

References:
· Canadian Mortgage and Housing Corporation (CMHC), Case Studies, Conservation Co-op, Ottawa,
   Ontario and Ministry of Social Service Building, Sooke, British Columbia. http://www.cmhc-
   schl.gc.ca
· Eco-Efficiency Resource Manual, EDCO. Trish Johnson Cover. Water Efficiency Branch,
   Environmental Services Department. Ottawa-Carlton Centre, Cartier Square, 111 Lisgar Street,
   Ottawa, ON K2P 2L7.
· Water Efficiency: A Guidebook for Small and Medium-sized Municipalities in Canada, Ontario
   Water Works Association, 1999




                                                                                   City of Toronto       1 - 17
SOURCE CONTROLS




Erosion and Sediment Control
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: This BMP is primarily
developed for construction sites where erosion and
sedimentation rates are usually very high. It aims at
prevention of erosion and containment of sediment from
leaving the site boundary.

Related SWMPs: Storm drain flushing; catch basin
cleaning; street cleaning.

Description: Erosion and sediment control is a
responsible act that should be implemented on every
construction site, before work begins and during              Erosion silt fencing at a construction site
construction. Planning of effective erosion and sediment
control should follow these seven basic principles.
·   Plan the development to fit the site.
·   Minimize the extent of the disturbed area and the duration of exposure.
·   Stabilize and protect disturbed areas as soon as possible.
·   Keep runoff velocities low.
·   Protect disturbed areas from runoff.
·   Retain sediment within the corridor or site area.
·   Implement a thorough maintenance and follow-up program.

Erosion and sediment control practices can be classified into:
· Temporary Cover Practices (e.g. seeding, mulching).
· Permanent Cover Practices (e.g. sodding, vegetative buffer strips).
· Erosion Control Practices (e.g. silt fencing, straw bales, sediment basins, sediment traps, sewer inlet
   traps).
· Sediment Control Practices (e.g., temporary runoff controls, rock check dam, interception
   berm/swale).

Application Requirements: A professional engineer or technician should prepare an erosion and
sediment control plan. A municipal inspector should check the practices after installation as well as after
major storm events.

Proven Effectiveness/Experience Elsewhere: Most of the practices have been implemented successfully
in North America. The requirements for new developments are typically applied in the Greater Toronto
Area, usually for new urban developments in the developing municipalities around Toronto. Within
Toronto, most development is smaller infill or redevelopment projects, with fewer options for sediment
and erosion control.

Cost Considerations: Construction and maintenance costs of erosion and sediment control practices
should be incorporated into the project cost. Municipal staff costs are incurred with review of erosion
control plans, the provision of site inspections and follow-up enforcement action.




1 - 18   City of Toronto
                                                                                   SOURCE CONTROLS



Objectives Addressed:

                         Technical Objectives (Terms of Ref.)                               Measure
                                                                                            Addresses
 1. Achieve healthy aquatic communities                                                        X
 2. Reduce fish consumption advisories
 3. Reduce erosion impacts                                                                           X
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                   X
 7. Achieve water and sediment objectives in watercourses and waterfront                             X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                              X
 10. Eliminate aesthetic nuisances                                                                   X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· A review will be made of sediment and erosion control requirements for infill and redevelopment
   projects that apply in the City of Toronto. No quantitative assessment of sediment load reductions
   will be made.

References:
· Technical Guidelines – Erosion and Sediment Control, MNR, 1989
· Guidelines on Erosion and Sediment Control for Urban Construction Sites, Ontario, 1987




                                                                                   City of Toronto       1 - 19
SOURCE CONTROLS




Used Oil Recycling
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Used oil recycling is a responsible alternative to improper disposal practices, such
as dumping in the sanitary sewer or storm drain system, applying oil to roads for dust
control, placing used oil and filters in the trash for landfill disposal or simply pouring
used oil on the ground.
Related SWMPs: Pollution prevention; drainage system control.

Description: The following approaches may be effective for used oil recycling:
·   Integrate efforts with a municipal solid waste program that likely has already been
    established.
·   Set up a municipal collection center funded by the municipality.
·   Contract out the collection and hauling of used oil to a private hauler/recycler.
·   Utilize the automobile service industry for collection of used oil.
·   Work with automotive parts supply stores to reduce incidents of automotive fluids left by customers
    on paved areas.
·   Create procedures for collection such as collection locations and schedule, acceptable containers and
    maximum amounts accepted.
·   Promote public participation through the use of posters, handouts, brochures and announcements in
    print and broadcast media; provide a list of the commercial recyclers.
·   Develop incentive programs for commercial locations and used oil recyclers.
Application Requirements: Arrangements must be made for collecting and delivering waste oil to a
recycling facility. A staff person is needed to coordinate these arrangements and review alternative
arrangements such as contracting out collection and haulage.
Public education is also a critical component of a successful program.

Proven Effectiveness/Experience Elsewhere: N/A
Cost Considerations: A collection facility or curbside collection may result in significant costs. Using
commercial locations (such as automobile service stations and fast-oil-change businesses) as collection
centers eliminates hauling and recycling costs for a municipality. If collection and recycling are
contracted out, staffing costs are minimal.




1 - 20   City of Toronto
                                                                                     SOURCE CONTROLS




Objectives Addressed:

                          Technical Objectives (Terms of Ref.)                                  Measure
                                                                                                Addresses
 1. Achieve healthy aquatic communities                                                            X
 2. Reduce fish consumption advisories                                                             X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                     X
 7. Achieve water and sediment objectives in watercourses and waterfront                               X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                                X
 10. Eliminate aesthetic nuisances                                                                     X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· A program review will be carried out. Difficult to assess quantitative benefits.

References:
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993.




                                                                                     City of Toronto   1 - 21
SOURCE CONTROLS




Household Hazardous Waste Collection

Wet Weather Flow Management Practice (WWFMP) Type: Source Controls
Primary Mechanism: This source control focuses on the
collection of deleterious chemicals that sometimes are
disposed of in a manner that threatens stormwater or sanitary
sewage quality. Household hazardous wastes (HHW) are
defined as waste materials that typically are found in homes or
similar sources and exhibit characteristics such as corrosivity,
ignitability, reactivity and /or toxicity, or are listed as
hazardous materials.
Household hazardous waste products include drain openers,
oven cleaners, wood and metal cleaners and polishes,
automotive oil and fuel additives, grease and rust solvents,
carburetor and fuel injection cleaners, starter fluid, batteries,   Environmental day household
paint thinners, paint strippers and removers, adhesives,            hazardous waste collection and
herbicides, pesticides, fungicides and wood preservatives.                 proper disposal

Household hazardous waste collection is a preventative, rather than curative measure and may reduce the
need for more elaborate treatment controls. Pollutants from household waste also end up in combined
sewer discharge, biosolids from the sewage treatment plant in sewage effluent, and for volatile organics,
as an air pollutant.

The benefits to storm water quality from HHW collection is unknown at present but best engineering
judgement indicates a potential of up to 15% reduction in loadings. (California Storm Water Best
Management Practice Handbooks; Stormwater Quality Task Force, March 1993. Fact Sheet SC31).
Related SWMPs: Solid waste program; Sewer use by-law enforcement; used oil recycling.

Description: The following considerations may be applicable for this BMP.
·   Integrate efforts with a municipal solid waste program that may have already been established.
    Optimize collection method(s) (for example, permanent, periodic, mobile and curbside) and
    frequency (for example, monthly and quarterly) based upon waste type, community characteristics,
    existing programs and budget.
·   Educate the public about hazardous materials in the home and the consequences of improper use or
    disposal.
·   Identify and promote the use of non-hazardous alternatives.
·   Identification of proper storage and disposal methods.
·   Promote participation in local HHW collection programs.
·   Distribute posters, handouts and educational material aimed at local schools.
·   Use public service announcements on local television, radio and newspapers.
·   Add utility bill inserts.
·   Make presentations to community organizations and develop a “speaker bureau” of local
    environmental professionals and recycling experts.
Application Requirements: Drop off sites and storage areas are needed. This BMP may require a
minimum of six trained persons per collection site or event to handle traffic, waste drop-off,



1 - 22   City of Toronto
                                                                                      SOURCE CONTROLS


characterization and disposal. Proper storage, disposal practices, and destinations and transport must be in
place.

Public education and participation must be planned and coordinated.
Proven Effectiveness/Experience Elsewhere: The Household Hazardous Waste Program for the
Regional Municipality of Waterloo is based at the regional Land Fill Site and has designated public dates
for receiving waste. Dates are publicized in public information flyers distributed throughout the region.
Cost Considerations: Cost depends on the type of program chosen and available disposal costs, and this
BMP can be a high-cost option compared to other source controls. This BMP may be limited to areas with
convenient access to hazardous waste disposal facilities and recycling facilities because of the
transportation costs. There are also significant liability issues involved with the collection, handling and
disposal of household hazardous waste.

Both collection and disposal can be expensive and are partly a function of frequency of collection, which
depends on the collection program implemented. Many communities have deferred HHW programs
because of the high cost.
Trained operators are required at collection centres.
Laboratory and detection equipment is necessary.
Extensive record keeping is required including dates, types and quantities of waste stored.
Objectives Addressed:

                           Technical Objectives (Terms of Ref.)                                  Measure
                                                                                                 Addresses
 1. Achieve healthy aquatic communities                                                             X
 2. Reduce fish consumption advisories                                                              X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                      X
 7. Achieve water and sediment objectives in watercourses and waterfront                                X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                                 X
 10. Eliminate aesthetic nuisances                                                                      X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· A program review will be carried out. Difficult to assess quantitative benefits.

References:
· David V. Galvin, Household Hazardous Waste in Municipal Wastewaters and Storm Drains: An
   important Target for Comprehensive Pollution Prevention Programs; WPCF Conference Proceedings
   Toronto, AC91-068-004, 1991.
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993.




                                                                                      City of Toronto   1 - 23
SOURCE CONTROLS




Safer Alternative Products
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Promote the use of less harmful and
environmentally damaging products. Alternatives exist for most
product classes, including fertilizers, pesticides, cleaning solutions
and most automotive and paint products. Promoting the use of less
harmful products can reduce the amount of toxic and deleterious
substances that enter stormwater and ultimately reach receiving
waters.

Related SWMPs: Hazardous waste reduction.
Description: This BMP has three key audiences: municipal
employees, the general public and small business. Existing
regulations already require municipalities to reduce the use of
hazardous materials. Municipal employees who handle potentially
harmful materials should be trained in the use of safer alternatives.
Purchasing departments should be encouraged to procure less              Special alternative product tags
hazardous materials.                                                         on retail store shelves
Safer alternatives for use by the general public are presented through education. Awareness is the key to
successful implementation of this BMP. It promotes a willingness to try alternatives and modify old
behaviours.

The following are examples of topics to be covered under a public education program.
· Automotive products - Less toxic alternatives are not available for many automotive products,
   especially engine fluids. But there are alternatives to car polishes, degreasers and windshield washer
   solution. Re-refined, recycled oil is also available.
· Cleaners - vegetable based or citrus-based soaps are available to replace petroleum-based
   soaps/detergents.
· Paint products - Water based paints, wood preservatives, stains and finishes are available.
· Pesticides - Specific alternative products or methods exist to control most insects, fungi and weeds.
· Fertilizers - compost and soil amendments are natural alternatives.

Application Requirements: Staff is needed to educate municipal employees and coordinate public
education efforts. There are no major equipment requirements to this BMP.

Proven Effectiveness/Experience Elsewhere: N/A

Cost Considerations: The primary cost of this BMP is for staff time (i.e. display or flyer creation). Use
of some alternative products may result in cost savings.




1 - 24   City of Toronto
                                                                                     SOURCE CONTROLS


Objectives Addressed:

                         Technical Objectives (Terms of Ref.)                                 Measure
                                                                                              Addresses
 1. Achieve healthy aquatic communities                                                          X
 2. Reduce fish consumption advisories                                                           X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                     X
 7. Achieve water and sediment objectives in watercourses and waterfront                               X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                                X
 10. Eliminate aesthetic nuisances                                                                     X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· A program review will be carried out. Difficult to assess quantitative benefits.

References:
· Hamilton-Wentworth Enviro-Guide for Students and Residents (1996). Hamilton-Wentworth
   Regional Environment Department, Waste Management Division. (905) 546-4417.
· Home Green Home – Your Guide to Homemade Alternative for Household Use. Communication
   Services, Region of Peel, 10 Peel Centre Dr., Brampton, ON L6T 4B9.
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993.




                                                                                     City of Toronto       1 - 25
SOURCE CONTROLS




Materials Storage Controls
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: This BMP primarily concerns material
delivery and storage for municipal and commercial operations.
Material storage controls can prevent or reduce the discharge of
pollutants to stormwater from material delivery and storage
areas. This can be done by reducing the storage of hazardous
materials on site, storing materials in designated areas, installing
secondary containment, conducting regular inspections and
training employees and subcontractors.

Related SWMPs: Pollution prevention and control;
environmental management system; spill control; building               Inside materials storage reduces
codes; fire codes.                                                                washoff

Description: The key is to design and maintain material storage areas that reduce exposure to stormwater
by:
·   Storing materials inside or under cover on paved surfaces;
·   Using secondary containment, where needed;
·   Minimizing storage and handling of hazardous materials and Inspecting storage areas regularly;
·   Keeping an ample supply of absorbent spill clean-up materials near the storage area.

This is a preventative BMP where the benefits include reduced liability, due diligence, and improved
public image for commercial operations.

Application Requirements: Employees must be educated in the proper handling and storage of materials
on site. Storage sheds and designated areas must meet building and fire code requirements. Accurate and
up-to-date inventories should be kept of all stored materials.

Proven Effectiveness/Experience Elsewhere: N/A

Cost Considerations: Costs will vary depending on the size of the facility and the necessary controls.
Employee education is paramount for successful BMP implementation.




1 - 26    City of Toronto
                                                                                     SOURCE CONTROLS


Objectives Addressed:

                          Technical Objectives (Terms of Ref.)                                 Measure
                                                                                               Addresses
 1. Achieve healthy aquatic communities                                                           x
 2. Reduce fish consumption advisories                                                            x
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                     x
 7. Achieve water and sediment objectives in watercourses and waterfront                               x
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures                                x
 10. Eliminate aesthetic nuisances                                                                     x
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· A program review will be carried out. Difficult to assess quantitative benefits.

References:
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993




                                                                                     City of Toronto       1 - 27
SOURCE CONTROLS




Vehicle Use Reduction
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Reduce the discharge of stormwater pollutants,
attributed to vehicle emissions that result in atmospheric fallout of
pollution, by highlighting the stormwater impacts; promoting the
benefits to stormwater of alternative transportation; and integrating
initiatives with existing regulations and programs.

Related SWMPs: Pollution prevention and control; energy and traffic
reduction programs.

Description: Studies show that reducing vehicle deposits on roadways
is likely to have a significant impact on local water quality, with
potential improvement in aquatic habitat. Highway drainage has been
shown to be toxic (Marsalek et al, 1999). A reduction in the amount of
pollutants entering major lakes and rivers, should reduce costs of
pollutant removal at water intake plants. Highway expansion needs and
road maintenance costs may also be reduced.
                                                                             Multiple occupancy vehicle
Efforts should be integrated with:
                                                                                    use encouraged
· government agencies, business and municipal programs to reduce
   vehicle use to improve air quality and public health;
· transit system redesign, expansion, and transit use promotions;
· residential street redesign including the addition of bicycle lanes and traffic calming initiatives;
· subdivision planning through community trail design, neighbourhood focused services;
· local bicycle and road safety programs;
· ride-share and trip reduction programs at government offices, major employers and universities;
· car-pooling between urban centres by the provision of no cost commuter parking, commuter lanes and
   toll reduction incentives;
· idling by-laws to reduce emissions;
· encouragement of alternative form of transportation, such as walking, bicycles and transit.
Application Requirements: A staff person is needed to track, review and comment on emerging
legislation and programs, and provide coordination of proactive efforts. Public education will be
paramount in eliciting support for this BMP.

Proven Effectiveness/Experience Elsewhere: Toronto Cities for Climate Protection Emissions
Reduction Program. Contact ICLEI, World Secretariat, City Hall 16th Floor, West Tower, Toronto. Phone
(416) 392-1475. The Toronto Case Study is posted at the website: www.iclei.org

Cost Considerations: Costs will be determined by the level of integration with related programs and
services, and the type of remediation undertaken. Projects can vary from the simple installation of
donated bicycle racks to the construction and maintenance of major commuter parking facilities.
Public education costs may include staff time for co-ordination, promotional materials, open houses and
other means of reaching target groups. Economic restraints may limit the level of integration between
departments and programs. The use of alternative transportation is highly dependent on its convenience
and relative cost.



1 - 28   City of Toronto
                                                                                    SOURCE CONTROLS


Objectives Addressed:

                          Technical Objectives (Terms of Ref.)                                 Measure
                                                                                               Addresses
 1. Achieve healthy aquatic communities                                                           X
 2. Reduce fish consumption advisories                                                                X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source                    X
 7. Achieve water and sediment objectives in watercourses and waterfront                              X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures
 10. Eliminate aesthetic nuisances                                                                    X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· Evaluation to be by program review and effect on traffic. The direct effect on pollution is difficult to
   assess.
References:
· Marsalek, J., Q. Rochfort, B. Brownlee, T. Mayer and M. Servos (1999). An exploratory study of
    urban runoff toxicity. Wat. Sci.Tech. Vol. 39. No. 21, pp.33-39.
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser &
    McKee, Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for
    Stormwater Quality Task Force, March 1993.




                                                                                    City of Toronto   1 - 29
SOURCE CONTROLS




Pool Drainage
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Outdoor swimming pools
require regular maintenance, involving chemical
treatment, backwashing (rinsing the filter with
clean water), and winterising. The drawdown of
pools prior to winter may release a large volume
of water to the surface water or to combined
sewers. Pools and spa water containing chlorine
can be toxic to aquatic life. Pool backwash water
containing sediment can cause sediment pollution
of surface waters.
Advice should be given to landowners by
municipalities, conservation authorities and
resident    associations   on     environmentally                   Winter pool drawdown.
acceptable ways to discharge pool backwash water
and drawdown water for winterizing.
Potentially toxic discharges will be avoided, groundwater infiltration will be enhanced, and nuisance
avoided. In combined sewer areas, flow reduction will result in reduced operational costs for conveyance
and treatment.
Related SWMPs: N/A

Description: Chemical additives for pools include chlorine or bromine, to maintain pool quality, and
products such as pH-up or muratic acid, which are occasionally used to maintain acid balance. Weekly
backwashing is necessary to remove particles from the pool filter. Backwashing can draw down the pool
water level by about one inch, and the backwashed water, containing sediments collected on the filter, is
usually discharged to the lawn or driveway. In the fall, owners must blow out the pool lines (i.e.
circulation, pump and filter) to avoid freezing and cracking over the winter. This winterizing activity
usually results in the drawdown of in-ground pool water level by about one quarter of the pool volume,
while above ground pools and spas are completely emptied.
Public education programs should stress the following:
· In order to have the least environmental impact, pools should be emptied at least three days after the last
   intense chemical application. The chlorine residual should be virtually absent.
· Backwash water is contaminated by filtered sediments and pool operators should discharge this water
   either to the sanitary sewer, or across the lawn to the storm sewer. By allowing pool water to flow
   across a lawn, some water will be lost through infiltration, some sediments will be filtered, and most
   remaining pool chemicals will volatilize to the air.
· If backwash water is discharged to the sanitary sewer, residents should take care to not also discharge
   winter drawdown water to the sanitary sewer because of the potential impacts of increased flow volume.
· In combined sewer areas, where no storm sewer exists, residents should be aware of the impacts of
   additional flow on the conveyance and treatment system. In these areas, infiltration measures should be
   encouraged to reduce the volume of water draining to the sewer system.
· Residents should be advised not to discharge the pool water onto neighbouring properties.




1 - 30   City of Toronto
                                                                                      SOURCE CONTROLS


·     Residents should be discouraged from discharging pool water into ravines to avoid erosion and slope
      failure.

Application Requirements: Municipal staff should be aware of the recommended pool discharge method
in order to respond to queries from residents. An information flyer can be distributed with water bills
(since pool owners use a substantial amount of water).
Proven Effectiveness/Experience Elsewhere: N/A
Cost Considerations: Costs will be limited to the production and distribution of public education
material.

Objectives Addressed:

                             Technical Objectives (Terms of Ref.)                                Measure
                                                                                                 Addresses
    1. Achieve healthy aquatic communities                                                          X
    2. Reduce fish consumption advisories                                                           X
    3. Reduce erosion impacts                                                                       X
    4 Re-establish natural hydrologic process                                                       X
    5. Re-establish natural features
    6. Virtual elimination of toxic contaminants using pollution prevention at source                   X
    7. Achieve water and sediment objectives in watercourses and waterfront                             X
    8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
    9. Improve body contact recreation in rivers and reduce beach closures                              X
    10. Eliminate aesthetic nuisances                                                                   X
    11. Reduce basement flooding
    12. Reduce sanitary sewer inflow and infiltration                                                   X
    13. Protect life and property from flooding

Opportunities Considerations:
· A program review will be carried out. Difficult to assess quantitative benefits.

References:
· Residential and Commercial Source Control Programs to Meet Water Quality Goals, Water
   Environment Research Foundation, Project 95-IRM-1, 1998, page 4-18.
· Swimming Pool Discharge Water, staff report, Toronto Region Conservation Authority, Nov. 11,
   1996.




                                                                                      City of Toronto   1 - 31
SOURCE CONTROLS




Spills Control
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Prevention or reduction of
discharge of pollutants to stormwater from above
ground storage tanks can be done by installing
safeguards against accidental releases, installing
secondary     containment,     conducting     regular
inspections and training employees in standard
operating procedures and spill cleanup techniques.
Vehicles and heavy equipment will leak and spill
fluids. The key is to reduce the frequency and
severity of leaks and spills and when they do occur,
prevent or reduce the environmental effects.

Transportation related spills are difficult to prevent.   Floatable spills containment and adsorption
A rapid spill response is necessary in these cases to
control spills.
Related SWMPs: N/A

Description: Efforts should be integrated with existing storage tank programs, through the local fire and
health departments, and with the local emergency response plan coordinated by the municipality.
·   Perform regular maintenance.
·   Keep ample supplies of spill cleanup materials at all facilities.
·   Update spill cleanup materials as changes occur in the types of chemicals stored on site.
    The following considerations may be effective in reducing spills associated with vehicle and
    machinery use:
    · Perform fluid removal and changes inside or under cover on paved surfaces.
    · Keep equipment clean and do not allow excessive build-up of oil and grease. Washwater should
        be properly filtered and disposed.
    · Recycle greases, used oil and filters, antifreeze, cleaning solutions, automotive batteries,
        hydraulic and transmission fluid.
    · Use dry cleanup methods.
·   Salt/pickled sand storage areas should be covered.
·   Drainage from stored materials should be treated to remove sediment.
Application Requirements: This BMP has no significant administrative or staffing requirements. Well-
trained employees can reduce human errors that lead to accidental releases or spills. Clean up materials
and methods should be available and appropriate for the spilled material.
Containment systems, either purchased or custom manufactured, should meet required Fire Code and
environmental standards.




1 - 32   City of Toronto
                                                                                    SOURCE CONTROLS


Proven Effectiveness/Experience Elsewhere: The Ontario Spills Action Centre recorded 3030 oil spills
in the City of Toronto (formerly Metropolitan Toronto) over a ten-year period (1988 – 1997). Sixty-three
percent of spills were cleaned up (80% or better containment); however, 30 % of spills were not cleaned
up, with oil entering the environment. (Li, 1998).

Cost Considerations: Costs will vary depending on the size of the facility and the necessary controls.

Objectives Addressed:

                        Technical Objectives (Terms of Ref.)                             Measure
                                                                                         Addresses
 1. Achieve healthy aquatic communities                                                     X
 2. Reduce fish consumption advisories                                                      X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source            X
 7. Achieve water and sediment objectives in watercourses and waterfront                      X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and
 spills
 9. Improve body contact recreation in rivers and reduce beach closures                       X
 10. Eliminate aesthetic nuisances                                                            X
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding

Opportunities Considerations:
· The spill response program for the City of Toronto will be reviewed.

References:
· James Li, “Statistical Analysis of Oil Spill Data in the City of Toronto” Conf. Proc. CSCE, June
   1998.




                                                                                    City of Toronto   1 - 33
SOURCE CONTROLS




Leaf Clearing and Removal
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Some reduction in the
discharge of nutrients and pollutants to stormwater
from street surfaces can be accomplished by
conducting leaf cleaning and removal during the fall
season. The primary benefit of this activity is the
removal of a high nutrient load from the storm sewer
and ultimately the creek system, which enhances
overall water quality.

Related SWMPs: Street sweeping; pollution
prevention and control; environmental management
system.

Description: The following approaches may be
effective to implement and maintain a municipal leaf        Leaf removal vacuum truck and equipment
pick-up program:
·   Prioritize pick-up to use the most technically advanced sweepers or truck mounted vacuums designed
    especially for this activity, at the greatest possible frequency in areas with the greatest numbers of
    trees. Provisions must be made for dumping, as the on board storage fills quickly with the bulky
    material. Areas with heavy leaf deposits may be most easily cleaned with loaders and dump trucks or
    a tuck mounted vacuum system that discharges into the back of the truck.
·   Residents should be informed of leaf collection arrangements, such as location of leaf collection
    centres; use of 2-ply kraft paper yard bags instead of plastic; curbside collection dates, restrictions
    and proper methods of accumulation. Residents should also be encouraged to dispose of leaf and yard
    waste in their own composters or by mowing and leaving on the lawn.
·   Keep accurate operation logs of tonnages collected to track program.

The following limitations may apply to this BMP.
· Parked cars are the primary obstacles to an effective program if leaves are deposited at the curbside.
· The effectiveness may also be limited by traffic congestion, construction projects, and climatic
   conditions.
· There is some potential for danger of children playing and hiding in curbside leaf piles.
Application Requirements: Sweeper operators, maintenance staff, supervisory and administrative
personnel are required. Traffic control bylaw officers may also be required to enforce parking restrictions.

Pick-up routes must be designed to optimize efficiencies. Leaf dump areas should be designated. Proper
disposal of collected materials. Composting should be encouraged.




1 - 34   City of Toronto
                                                                                  SOURCE CONTROLS


Proven Effectiveness/Experience Elsewhere: City of Kitchener “2000 Leaf to Compost Program”,
Public Works Department. Leaf compost is sold for garden application to area residents.

Cost Considerations: A leaf pick-up program requires a significant capital, operating and maintenance
budget. Some public education is also required, which has associated information distribution costs. The
end product of leaf collection may be composted material available for municipal and public use.




                                                                                  City of Toronto   1 - 35
SOURCE CONTROLS



Objectives Addressed:

                           Technical Objectives (Terms of Ref.)                           Measure
                                                                                          Addresses
  1. Achieve healthy aquatic communities                                                     X
  2. Reduce fish consumption advisories                                                      X
  3. Reduce erosion impacts
  4 Re-establish natural hydrologic process
  5. Re-establish natural features
  6. Virtual elimination of toxic contaminants using pollution prevention at source
  7. Achieve water and sediment objectives in watercourses and waterfront                     X
  8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
  9. Improve body contact recreation in rivers and reduce beach closures                      X
  10. Eliminate aesthetic nuisances                                                           X
  11. Reduce basement flooding
  12. Reduce sanitary sewer inflow and infiltration
  13. Protect life and property from flooding

Opportunities Considerations:
· This measure will be evaluated by a program review. The actual performance in meeting objectives is
   difficult to evaluate quantitatively.
References:
· California Storm Water Best Management Practice Handbooks; prepared by Camp Dresser & McKee,
   Larry Walker Associates, Uribe and Associates, Resources Planning Associates, for Stormwater
   Quality Task Force, March 1993.




1 - 36   City of Toronto
                                                                                    SOURCE CONTROLS




Modifying Engineering Standards
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Reduce pollutant
sources near source through absorbing and
filtering of pollutants. Reduced runoff by
encouraging infiltration.

Related WWFMPs: Alternate conveyance
controls (roadside ditches). At source controls
(storm gardens, surface storage / infiltration).

Description: Changes to engineering standards
to promote the use of surface storage and
drainage (through grassed areas). Utilizing              Engineering standards have to be changed to allow
grading standards to promote surface ponding                    for alternatives to roadside ditches
and / or increasing the detention time of surface
water on grassed areas. Reduce the minimum and maximum surface slopes, and provide retention areas.
Change road design standards to promote roadside swales. Often times these require measures to promote
infiltration such as rock or stone filled basins or trenches.
Application Requirements: Will require revisions to engineering standards and site plan standards (and
approval processes). Will require public education for the acceptance of periodic surface ponding (and
conveyance).
Proven Effectiveness / Experience Elsewhere: Roadside ditches have been used historically in some
municipalities. Currently, some municipalities are utilizing roadside ditches in urban areas. Grassed
swales have been evaluated for effectiveness.

Cost Consideration: Some research has concluded that capital and operating costs are lower for roadside
ditch applications compared to curb and gutter applications.




                                                                                    City of Toronto   1 - 37
SOURCE CONTROLS




Objectives Addressed:

                           Technical Objectives (Terms of Ref.)                             Measure
                                                                                            Addresses
 1.      Achieve healthy aquatic communities                                                   X
 2.      Reduce fish consumption advisories
 3.      Reduce erosion impacts                                                                 X
 4.      Re-establish natural hydrologic process                                                X
 5.      Re-establish natural features
 6.      Virtual elimination of toxic contaminants using pollution prevention at source         X
 7.      Achieve water and sediment objectives in watercourses and waterfront
 8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and
         spills
 9.      Improve body contact recreation in rivers and reduce beach closures                    X
 10.     Eliminate aesthetic nuisances
 11.     Reduce basement flooding
 12.     Reduce sanitary sewer inflow and infiltration
 13.     Protect life and property from flooding

Opportunities Considerations:
· Use of natural drainage systems such as site level infiltration and natural conveyance systems are
   being evaluated quantitatively through the modelling effort in this study. Current design standards
   will be reviewed to ensure that they do not impede or prevent application of the source and
   conveyance measures proposed in the study. The existing infrastructure that is in rural cross sections
   utilizing roadside ditches should be maintained and upgraded to ensure that the benefits of this
   practice are maintained.

References:
· MOE, 2000, (DRAFT) Stormwater Management Plannng and Design Manual
· An Evaluation of Roadside Ditches and Other Related Stormwater Management Practices, J. F.
   Sabourin and Associates, Published by TRCA, 2000.




1 - 38   City of Toronto
                                                                                   SOURCE CONTROLS




Cross Connection Control Program
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: A significant source of
stormwater pollution can be removed by preventing
unwarranted physical connections to the storm drain
system from sanitary sewers and floor drains through
regulation, regular inspection, testing and education.
An active program will reduce liability (shows due
diligence) for pollution from storm sewers.

Related SWMPs: Sewer system operations;
downspout disconnection bylaw; sewer rehabilitation.

Description: The following steps are components of
this BMP:
·   Ensure that existing provincial municipal building
    and plumbing codes prohibit physical connection
    of non-stormwater discharges to the storm drain        Regular testing of storm drains to prevent
    system.                                                           unwanted pollution
·   Require visual inspection of new developments or
    redevelopments during development phase.
·   Develop documentation and record keeping protocols to track inspections and catalogue the storm
    drain system.
·   Use techniques such as zinc chloride smoke testing, fluorometric dye testing and television camera
    inspection to verify physical connections.
Application Requirements: Building and plumbing inspectors must verify and document inappropriate
discharges into the storm drain system. Additional follow-up time is required to verify that appropriate
corrective measures have been carried out.
A community awareness program (using various media), can target appropriate audiences (homeowners,
businesses and contractors) to warn against improper connections to the storm drain system and
encourage public reporting of illegal connections through a community hotline telephone number.
Equipment needed may include:
·   Personal protective equipment (hard hats, boots, plastic gloves, coveralls);
·   Sampling containers and storm water test kits;
·   Self-contained breathing apparatus;
·   Oxygen/combustible and hydrogen sulfide gas meters;
·   CCTV pipeline television camera;
·   Smoke and dye testing equipment.

Notify community and local fire departments before testing with zinc chloride smoke testing and
fluorometric dye testing in targeted areas.

Proven Effectiveness/Experience Elsewhere: N/A




                                                                                   City of Toronto   1 - 39
SOURCE CONTROLS


Cost Considerations: Zinc chloride smoke testing, fluorometric dye testing and television camera
inspection can be costly. Labour and equipment cost for verification of plumbing connections is also a
factor.

Objectives Addressed:

                           Technical Objectives (Terms of Ref.)                          Measure
                                                                                         Addresses
 1. Achieve healthy aquatic communities                                                     X
 2. Reduce fish consumption advisories                                                      X
 3. Reduce erosion impacts
 4 Re-establish natural hydrologic process
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source           X
 7. Achieve water and sediment objectives in watercourses and waterfront                     X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills       X
 9. Improve body contact recreation in rivers and reduce beach closures                      X
 10. Eliminate aesthetic nuisances                                                           X
 11. Reduce basement flooding                                                                X
 12. Reduce sanitary sewer inflow and infiltration                                           X
 13. Protect life and property from flooding

Opportunities Considerations:
· A program review will be carried out. Difficult to assess quantitative benefits.

References:
· Investigation of Inappropriate Pollutant Entries into Storm Drainage Systems – A Users Guide,
   EPA600/R-92/238, January, 1993.
· Canviro Consultants, 1987, Don River Dry Weather Survey, TAWMS Technical Report #11, MOE.




1 - 40   City of Toronto
                                                                                     SOURCE CONTROLS




Roof Leader Disconnection
Wet Weather Flow Management Practice                (WWFMP) Type: Source
Controls

Primary Mechanism: Direct inflow

Related WWFMPs: Lot level storage/infiltration, weeping tiles/foundation
drains.

Description: Roof leaders are typically connected to the combined drainage
system in older portions of many cities or to the storm sewer system, and
illegal connections to the sanitary sewer also exist. Illegal sanitary connections
often result after an area has been partially separated, resulting in the roof
leaders being connected to the converted sanitary sewer. These connections all
contribute significant runoff directly to the combined, storm, or sanitary system
following a storm event. Disconnection of roof leaders has a minimal effect on
pollutant removal since very little pollutant load accumulates on rooftops.               Rain barrel

Application Requirements: Disconnection of the roof leaders is a very effective means of reducing
direct runoff where site conditions and grading allow roof runoff to be directed to sufficiently sized
vegetated areas or collected in rain barrels. It is most successful where positive drainage exist from the
building to the street and where there is also good street drainage. A negative effect to roof leader
disconnection is that it can aggravate localized site drainage problems in areas where surface water
collects because of impervious soils or inadequate site drainage. The major problem with this alternative
is proper implementation and acceptability.

A rain barrel can be used under any roof leader but may need a few modifications in order to operate
effectively and safely. Consideration must be given to handling the overflow once the barrel is filled.

Proven Effectiveness / Experience Elsewhere: The City of St. Catharines has implemented a roof leader
disconnection by-law, which makes disconnection of roof leaders mandatory. The City of St. Catharines
enforcing this by-law on an area basis with follow up inspections to confirm compliance. Final
inspections are still being completed in some areas. In areas in which final inspections have been
completed, compliance with the by-law has been achieved. The impacts of this disconnection program to
the overall runoff volume has yet to be observed through flow monitoring in local areas but the program
has resulted in an estimate 4% reduction in storage requirements at the wastewater treatment plant. (City
of St. Catherines)

The City of Sarnia has implemented a voluntary roof leader disconnection program. Although roof leader
disconnection is an effective control option for reducing basement flooding, with limited water quality
benefits, complete disconnection compliance by homeowners is difficult to achieve. In Sarnia,
approximately 50% voluntary disconnection compliance was achieved. Complaints of seepage through
basement walls and backyard ponding have been reported, but are considered a result of poor lot grading.
(City of Sarnia)

The City of Toronto has been carrying out a roof leader disconnection program within the combined
sewer area since 1994. Approximately 1700 homes are canvassed each year and the residents are


                                                                                     City of Toronto   1 - 41
SOURCE CONTROLS


informed of the benefits of roof leader disconnection. A site visit is made to properties where residents
are interested in participating in the program. A conditional assessment of the property is made along with
a list of required materials. These materials are delivered to the homeowner and the resident is responsible
for disconnecting the roof leader and installing the new material. Toronto experiences a 10% annual
participation rate, however, this number may be lower than actual because it does not include residents
that disconnect on their own after receiving information from the canvas.
A study conducted for the City of Hamilton (D. Henry, and W. James, 1981) utilized SWMM to estimate
the reduction in stormwater runoff and peak discharge as a result of disconnecting roof leaders.
Disconnecting roof leaders and distributing the runoff onto lawns and gardens was estimated to reduce the
total 2 year design storm runoff volume by 10% to 24%. This study also found that the length and
intensity of the storm event and the amount of pervious area available to accept the rooftop runoff
effected the total percent reductions.
Cost Considerations: Disconnection of roof leaders are simple and low in cost, as long as there is
adequate lot grading. Politically, however, disconnection programs are difficult to implement.

Objectives Addressed:

                            Technical Objectives (Terms of Ref.)                               Measure
                                                                                               Addresses
 1.      Achieve healthy aquatic communities
 2.      Reduce fish consumption advisories
 3.      Reduce erosion impacts
 4.      Re-establish natural hydrologic process                                                   X
 5.      Re-establish natural features                                                             X
 6.      Virtual elimination of toxic contaminants using pollution prevention at source
 7.      Achieve water and sediment objectives in watercourses and waterfront                      X
 8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and               X
         spills
 9.      Improve body contact recreation in rivers and reduce beach closures
 10.     Eliminate aesthetic nuisances
 11.     Reduce basement flooding                                                                  X
 12.     Reduce sanitary sewer inflow and infiltration                                             X
 13.     Protect life and property from flooding

Opportunities Considerations:
· The option will be assessed in further detail on a subwatershed or catchment area based on new
   development or redevelopment areas and/or physical implementation criteria.

References:
· Shelley Grice, The Development and Promotion of “Recycle Your Rain”: A City of Toronto Lot
   Level Stormwater Diversion Initiative, in Stormwater Technology Transfer Conference, Stormwater
   Assessment Monitoring and Performance Program, MOE, 1998.




1 - 42    City of Toronto
                                                                                     SOURCE CONTROLS




Foundation Drain Disconnection
Wet Weather Flow Management Practice (WWFMP) Type: Source
Controls

Primary Mechanism: Infiltration

Related WWFMPs: Sump pumps, roof leader disconnection, illicit
connections

Description: Foundation drains are connected to the sewer laterals (the
pervious pipes surrounding the house that accumulate water during
storms). Foundation drains are installed to lower the water table around
the structure to prevent lot flooding, structural damage, and flooding into
the house, especially if the home has a basement. As of 1991, the Ontario
Building code will not permit foundation drains from new developments
to be connected to sanitary sewers.
                                                                           Foundation drain connected to
Application Requirements: Illicit foundation drains connected to the         sump pump discharging to a
sanitary sewer are discovered during field inspections (smoke testing),             soakaway pit
or during replacement of the sewer laterals. Determination of illicit foundation drains is labour intensive
and disconnection of the foundation drain can be costly and difficult to implement. The elimination of
foundation drains would not have a measurable impact on the volume of combined sewer overflows or
their pollutant quality. However, disconnection of foundation drains from the storm drain (sump pump)
would eliminate the excessive hydraulic fluctuations but may result in possible structural damage and
basement flooding.

Proven Effectiveness / Experience Elsewhere: The City of Edmonton has developed a cross connection
program, which is to eliminate all illicit connections, including foundation drains. The impact of
eliminating foundation drains has not been monitored.

Cost Considerations: Foundation drains are typically only disconnected when the local sewer and
service connections are being replaced. The cost to benefit ratio is very high and therefore not an option
frequently considered.




                                                                                     City of Toronto   1 - 43
SOURCE CONTROLS


Objectives Addressed:

                            Technical Objectives (Terms of Ref.)                          Measure
                                                                                          Addresses
 1.      Achieve healthy aquatic communities
 2.      Reduce fish consumption advisories
 3.      Reduce erosion impacts
 4.      Re-establish natural hydrologic process
 5.      Re-establish natural features
 6.      Virtual elimination of toxic contaminants using pollution prevention at source
 7.      Achieve water and sediment objectives in watercourses and waterfront
 8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and
         spills
 9.      Improve body contact recreation in rivers and reduce beach closures
 10.     Eliminate aesthetic nuisances
 11.     Reduce basement flooding                                                            X
 12.     Reduce sanitary sewer inflow and infiltration                                       X
 13.     Protect life and property from flooding

Opportunities Considerations:
· The option will be assessed in further detail on a subwatershed or catchment area based on new
   development or redevelopment areas and/or physical implementation criteria.

References:
· Ontario Building Code
· City of Edmonton, Alberta website on roof leader disconnection: www.gov.edmonton.ab.ca




1 - 44    City of Toronto
                                                                                     SOURCE CONTROLS




Lot Level Storage/Infiltration Systems
(Rear Yard Ponding)
Wet Weather Flow Management                 Practice
(WWFMP) Type: Source Controls

Primary Mechanism: Flow retention; infiltration;
recharge

Related WWFMPs: Reduced lot grading; soakaway
pits; infiltration trenches/basins

Description: Discharge of roof leaders to rear yard
ponding areas can be used to reduce peak flow rates
in receiving systems, reduce total volume of runoff
from a given event and contribute somewhat to             Discharge of roof leaders to rear yard ponding
quality improvement by reducing atmospheric                                   areas
pollutants through natural filtration.

Areas for ponding can be created in the rear yards or along rear lot lines. Roof leaders should discharge
to the ponding area via a splash pad and overland flow route. Water is detained in the pond until it either
evaporates or infiltrates. Depth of pond depression should not exceed 1 m with an overland relief flow
route to accommodate depths greater than this amount.

Target storage volumes should range from a minimum of 5 mm to a maximum of 20 mm over the rooftop
area, as 90% of rainfall events within the Toronto area are less than this latter amount.
Ponding configuration will be determined by site specific layout of the development. In general, pond
depth should be minimized and length should be maximized as compared to width to prevent short-
circuiting, reduce the potential for groundwater mounding and maximize the potential for infiltration.

Pond should be located a minimum of 4 metres away from the building to minimize the impact on the
foundation drainage. Infiltration can be enhanced by tilling the ponding area to a depth of 300 mm prior
to placing sod and/or providing an infiltration trench below the pond area.

Application Requirements: Primarily applicable to new developments or re-development. Difficult to
implement for retrofit or improvement projects due to existing site constraints such as established fence
lines and lot grades. Appropriate consideration in areas where land is relatively flat and soil type is
appropriate (minimum percolation rate 5 mm/hr).

Proven Effectiveness / Experience Elsewhere: Moderately effective in reducing peak flows and total
runoff if applied extensively within the neighbourhood. Minor improvement in water quality by partial
removal of atmospheric pollutants. May result in local groundwater mounding with resultant impact on
building’s perimeter drainage. May also impact owner’s use of property if infiltration is prolonged.

This alternative has been applied in new developments and re-developments but on a selective basis in
retrofit conditions.




                                                                                     City of Toronto   1 - 45
SOURCE CONTROLS


Cost Considerations: Relatively inexpensive to implement at development stage. Costs are relatively low
compared to construction costs for infiltration trenches.

Objectives Addressed:

                            Technical Objectives (Terms of Ref.)                           Measure
                                                                                           Addresses
 1.      Achieve healthy aquatic communities
 2.      Reduce fish consumption advisories                                                    X
 3.      Reduce erosion impacts
 4.      Re-establish natural hydrologic process                                               x
 5.      Re-establish natural features
 6.      Virtual elimination of toxic contaminants using pollution prevention at source
 7.      Achieve water and sediment objectives in watercourses and waterfront                  X
 8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and           X
         spills
 9.      Improve body contact recreation in rivers and reduce beach closures                   X
 10.     Eliminate aesthetic nuisances                                                         X
 11.     Reduce basement flooding                                                              X
 12.     Reduce sanitary sewer inflow and infiltration
 13.     Protect life and property from flooding                                               X

Opportunities Considerations:
· The option will be assessed in further detail on a subwatershed or catchment area based on new
   development or redevelopment areas and/or physical implementation criteria.

References:
· Ministry of the Environment, “Stormwater Management Planning and Design Manual”, Draft Final
   Report, November 1999, Source Control, Chapter 4.
· Alberta Environmental Protection, Standards and Guidelines Branch, “Stormwater Management
   Guidelines’, Section 8, December 1997.




1 - 46    City of Toronto
                                                                                    SOURCE CONTROLS




Lot Grading
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Runoff detention/depression
storage/infiltration

Related WWFMPs: Lot level storage/infiltration;
soakaway pits.

Description: Lot grading can be used to reduce storm
runoff by promoting recharge and natural infiltration.
Typical development standards require minimum lot grades
of 2% for adequate drainage of stormwater away from
buildings. Alternative Development Standards have been
proposed (Ministry of Housing, Ministry of Municipal            Proper lot grading can reduce storm runoff
Affairs, 1994) which permit reduction of minimum lot               and promote recharge and infiltration
grades from 2% to 0.5%.              Despite this, some
municipalities do not permit use of the revised standard and the designer should confirm acceptability of
this practice with the local municipality prior to implementation.

Grading within 2-4 metres of a building should be maintained at 2% or higher to ensure that foundation
drainage problems do not occur. Subject to compliance with local municipal standards, areas outside of
this boundary may be graded at less than 2% to create greater depression storage and promote infiltration.
Infiltration can also be enhanced by scarification of the lots to a depth of approximately 300 mm prior to
laying sod. This will tend to reduce the compaction that normally occurs during construction and
promote improved infiltration.

One side impact of reduced lot grading is the potential restriction on actual use of the property by the
homeowner following a storm event. Water ponding associated with the reduced grades may take a day
or two to fully drain which could restrict active use of the land during that period. As a result, public
education as to the benefits of reduced grading standards should be undertaken wherever the practice is to
be implemented.

Application Requirements: Primarily applicable to new developments or re-development. Difficult to
implement for retrofit or improvement projects due to existing constraints such as established fence lines
and lot grades. May be considered in areas where the land is relatively flat and the soil is relatively
permeable (minimum percolation rate ³ 5 mm/hr). In hilly areas, reduced grading is not generally
desirable, as alterations to the natural topography should be minimized.

Proven Effectiveness / Experience Elsewhere: There is little experience with the benefits of reduced lot
grading applied as a standard practice on a subdivision scale; however, it is logical to expect that its
implementation would reduce end-of-pipe detention requirements by extending runoff time and reducing
runoff volumes. The benefits of reduced grades can be better assessed based on an increase in pervious
area depression storage.




                                                                                    City of Toronto   1 - 47
SOURCE CONTROLS


Cost Considerations: Relatively inexpensive to implement at development stage. Additional cost limited
to minor increase in construction cost for the alteration of the lot prior to laying sod.

Objectives Addressed:

                           Technical Objectives (Terms of Ref.)                           Measure
                                                                                          Addresses
 1.      Achieve healthy aquatic communities
 2.      Reduce fish consumption advisories
 3.      Reduce erosion impacts                                                              X
 4.      Re-establish natural hydrologic process                                             X
 5.      Re-establish natural features
 6.      Virtual elimination of toxic contaminants using pollution prevention at source
 7.      Achieve water and sediment objectives in watercourses and waterfront                X
 8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and         X
         spills
 9.      Improve body contact recreation in rivers and reduce beach closures
 10.     Eliminate aesthetic nuisances
 11.     Reduce basement flooding                                                            X
 12.     Reduce sanitary sewer inflow and infiltration
 13.     Protect life and property from flooding

Opportunities Considerations:
· The option will be assessed in further detail on a subwatershed or catchment area based on new
   development or redevelopment areas and/or physical implementation criteria.

References:
· Ministry of the Environment, “Stormwater Management Planning and Design Manual”, Draft Final
   Report, November 1999, Source Control, Chapter 4.
· Alberta Environmental Protection, Standards and Guidelines Branch, “Stormwater Management
   Guidelines’, Section 8, December 1997.




1 - 48   City of Toronto
                                                                                     SOURCE CONTROLS




Catchbasin Restrictors/Inlet Controls
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls
Primary Mechanism: Flow restriction; controlled discharge

Related WWFMPs: Parking lot storage, storm sewer orifices.

Description: Inlet control devices (ICDs) can be used in storm sewer inlet
structures to restrict the discharge from local catchment areas resulting in
reduced peak flow rates in receiving sewer systems. They can also be
applied to catchbasins in the street to limit peak flow downstream. The
resulting overland flow and ponding has to be checked, and should be
within municipal allowable limits.

This management practice focuses primarily on quantity control with
minimal benefits related to water quality.            Target areas include
commercial and industrial parking areas where short term storage of
storm runoff can be practically accommodated. The practice is not          Diagram of a catchbasin
practical in residential areas due to the small parking areas involved.          restrictor

Catchbasin restrictors are applied in flow slipping techniques to maintain runoff as surface flow in areas
where storm or combined pipe is undersized or when redirecting flow from a combined sewer to a storm
sewer.

Types of ICDs include flow restrictors for use in catchbasins or orifices for use in maintenance holes.
ICDs can be selected from a range of available pre-manufactured devices or specifically designed where
applicable. The design discharge rate will be dependent on the volume of storage and the required
drainage period. Typically, ponding depths should not exceed 300 mm and time to drain should not
exceed 1 hour.

Preferably, ICDs should be located in maintenance holes at the property boundary to facilitate public
access for checking operability by the municipality at their convenience. Where this is not possible due to
site constraints, individual devices can be placed on catchbasins within the property in order to maximize
storage on the lot.

Application Requirements: Primarily applicable to new developments or re-development. Difficult to
implement for retrofit or improvement projects due to existing site constraints but have been used by
several municipalities on a limited scale.

Proven Effectiveness / Experience Elsewhere: Highly effective in reducing downstream flow rates.
Total volume or runoff is not reduced as discharge simply occurs at a controlled rate over a longer period
of time. Contributes to CSO reduction.

Flow slipping, with the use of catchbasins restrictors, is being installed in the Wishing Well area of
Scarborough. Flow throttling devices are presently being used within the Cities of Toronto and Vaughan
and the Town of Markham.




                                                                                     City of Toronto   1 - 49
SOURCE CONTROLS


Cost Considerations: Relatively inexpensive to implement at development stage.           Additional costs
limited to increases in construction costs for additional drainage appurtenances.

Objectives Addressed:

                             Technical Objectives (Terms of Ref.)                             Measure
                                                                                              Addresses
 1.      Achieve healthy aquatic communities                                                     X
 2.      Reduce fish consumption advisories                                                      X
 3.      Reduce erosion impacts
 4.      Re-establish natural hydrologic process
 5.      Re-establish natural features
 6.      Virtual elimination of toxic contaminants using pollution prevention at source
 7.      Achieve water and sediment objectives in watercourses and waterfront                    X
 8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills      X
 9.      Improve body contact recreation in rivers and reduce beach closures                     X
 10.     Eliminate aesthetic nuisances                                                           X
 11.     Reduce basement flooding                                                                X
 12.     Reduce sanitary sewer inflow and infiltration
 13.     Protect life and property from flooding                                                 X

Opportunities Considerations:
· The option will be assessed in further detail on a subwatershed or catchment area based on new
   development or redevelopment areas and/or physical implementation criteria.

References:
· Water Pollution Control Federation, “Combined Sewer Overflow Pollution Abatement”, Manual of
   Practice FD-17, 1989.




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                                                                                     SOURCE CONTROLS




Porous Pavement
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls
Primary Mechanism: Infiltration or filtration

Related WWFMPs: Soak-away pits, dry ponds, vegetative filter
strips, lot level depressions.

Description: Porous pavements consist of various surface treatment
from concrete pavers to porous asphalt. Concrete pavers normally
rely on the paver joints to provide the pervious area for infiltration,
there are concrete block designs which include spaces within the
block to provide pervious area. Porous asphalt technology involves
the installation of a pervious, open graded asphalt wearing course
over a base course with large void spaces. The base course functions
as a detention reservoir. Rain then passes through the wearing course,
collects in the void spaces of the base course, and ultimately drains     Interlocking stone as porous
away by natural infiltration.                                                      pavement

Application Requirements: Porous pavement has been a suggested technique for areas such as parking
lots, playgrounds, and lightly travelled roads. The effect is to reduce the amount of stormwater runoff
which enters the sewer system.

Porous pavement is superior to conventional pavement in terms of traffic safety due to increased skid
resistance and vehicles are less susceptible to hydroplaning. The impacts of porous pavement on the
natural environment is essentially the same as infiltration trenches and basins. Porous pavement diverts a
large fraction of the annual runoff volume into the soil, which helps maintain baseflows, and can prevent
serious erosion immediately downstream. A problem associated with runoff infiltration is the risk of
groundwater contamination, therefore it is not recommended to apply this technology where groundwater
contamination is a sensitive issue. Porous pavement application is restricted to areas where conditions are
favourable in terms of soil type, depth of groundwater, land slope and proximity to water supply wells.

Contaminants loads generated from porous pavements are reduced since the amount of direct runoff from
the surface is reduced. More contaminant loads infiltrated below the surface, therefore, the surface runoff
has less contaminants, showing that porous pavement exhibits excellent performance with respect to
runoff reduction and pollution abatement (University of Guelph).

Proven Effectiveness / Experience Elsewhere: Graduate students from the University of Guelph
conducted a research program that investigated the environmental benefits of using porous pavers and
asphalt. Four types of pavement were installed; asphalt, interlocking stone, and two UNI ECO-STONE
pavements. The research program investigated the improvement of parking-lot runoff quality, thermal
enrichment of runoff from pavement, and long term modelling of infiltration through pavers. For the 23
contaminants examined, loads from the asphalt surface were always greater than from the other pavings,
mostly because the asphalt was 100% impervious and permeable pavements significantly reduces surface
runoff contaminant loads.

Field studies have demonstrated that porous pavement is capable of achieving high levels of removal of
both soluble and fine particulate pollutants. Porous pavement is primarily designed to remove pollutants



                                                                                     City of Toronto   1 - 51
SOURCE CONTROLS


deposited on the pavement surface during the exfiltration process. A study conducted by Schueler
provides the following estimated pollutant removal rates of pavement systems from long term monitoring
studies; 82-95% sediments, 65% phosphorous, 80-85% Total Nitrogen, 82% COD, 99% Zinc, 98% Lead.
(T.R. Schueler, 1987).

The City of Toronto has installed porous pavers in lane ways, subject to soil conditions. The pavers were
installed approximately 5 years ago. The initial level of infiltration and how this level decreases over time
has not been monitored.
The number of homeowners installing porous pavers or paving stone on their properties have increased,
however, the majority of these installations are attributed to aesthetic improvements.

Cost Considerations: The installation and maintenance cost of porous pavements or pavers is more
expensive than conventional asphalt or concrete.

Objectives Addressed:

                             Technical Objectives (Terms of Ref.)                               Measure
                                                                                                Addresses
 1.      Achieve healthy aquatic communities
 2.      Reduce fish consumption advisories
 3.      Reduce erosion impacts                                                                     X
 4.      Re-establish natural hydrologic process                                                    X
 5.      Re-establish natural features
 6.      Virtual elimination of toxic contaminants using pollution prevention at source
 7.      Achieve water and sediment objectives in watercourses and waterfront
 8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and
         spills
 9.      Improve body contact recreation in rivers and reduce beach closures
 10.     Eliminate aesthetic nuisances
 11.     Reduce basement flooding
 12.     Reduce sanitary sewer inflow and infiltration
 13.     Protect life and property from flooding

Opportunities Considerations:
· The option will be assessed in further detail on a subwatershed or catchment area based on new
   development or redevelopment areas and/or physical implementation criteria.

References:
· CH2M Gore & Storrie and Infrastructure Systems Ltd., “Edmonton CSO Control Strategy, Sewage
   System Assessment and Operation Optimization, Task 3”, 1997.
· University of Guelph website; www.eos.uoguelph.ca/webfiles/james
· Promotional brochure published by UNI-LOCK on porous pavers.
· T.R. Schuler, “Controllig Urban Runoff: A Practical Manual for Planning and Designing Urban Best
   Management Practices”, 1987, prepared for Washington Metropolitan Water Resources Planning
   Board.




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                                                                                      SOURCE CONTROLS




Soakaway Pits
Wet Weather Flow Management Practice (WWFMP) Type: Source Controls

Primary Mechanism: Flow retention; infiltration; recharge

Related WWFMPs: Reduced lot grading; infiltration
trenches/basins; lot level storage/infiltration systems.

Description: This stormwater lot level control practice
provides for infiltration of roof drainage into the ground by
directing the rain water roof leader to an underground
infiltration trench referred to as a “soakaway pit”. The
“soakaway pit” typically serves a single lot and does not
receive road runoff. This SWMP provides similar benefits to
the rear yard ponding option (flooding and erosion potential
benefits and treatment of atmospheric pollutants).                    Soakaway pit for roof drainage

Depth from the bottom of the soakaway pit to either the seasonally high water table or to bedrock should
be greater than or equal to 1 metre. The pit should be located at least 4 metres away from the building to
prevent excessive drainage to the foundation drainage. The pit should be filled with 50 mm clear stone
and completely enveloped with filter cloth to prevent mitigation of surrounding native soil into the pore
spaces of the stone fill. The roof leader should extend underground into the pit and be perforated for the
full length of the pit to allow distribution of flow along the length of the pit. The perforated pipe should
be located 75-150 mm from the top of the pit.

The vertical portion of the roof leader should contain a removable section above ground level with a filter
screen for maintenance purposes and to prevent leaves and debris from being conveyed to the soakaway
pit. An overflow pipe to a splash pad should be provided above the removable section to guard against
plugging and backups in the event of inadequate maintenance/cleanout of the removable filter screen.

Typically, the pit should be located as close to the ground surface as possible but this will depend on
depth of storage, potential for frost heave and characteristics of the surrounding soil. Shallow pits are
generally preferred since surficial soils are usually coarser (higher percolation rate) than deeper soils.
Again however, this will depend on the soil stratigraphy of the site.

Subject to site limitations, the length of the pit (direction of inflow) should be maximized compared to the
width to ensure proper distribution of water into the entire pit and to minimize the potential for
groundwater mounding.

Storage depths will be dictated by the permeability of the native soil but generally should not exceed 1.5
m from a cost perspective.

A minimum storage volume of 5 mm over large industrial/commercial rooftop areas should be
accommodated in the soakaway pit. The maximum target storage volume should be 20 mm over the
rooftop area since approximately 90% of all daily rainfall depths are less than this amount.




                                                                                      City of Toronto   1 - 53
SOURCE CONTROLS


For areas with compact build forms, common pits can be located in neighbourhood park areas or along
rear lot lines.

In all cases, soakaway pit design should be based on site specific geotechnical investigations and
recommendations to ensure optimum configuration and performance.

Application Requirements: Primarily applicable to new development or re-development. It could be
implemented in existing lots where space and soil conditions permit, however, disruption and restoration
costs would be significantly higher. A soil report is required to confirm the viability of this SWMP.
Soakaway pits can be implemented for soil types where the minimum percolation rate exceeds 15 mm/hr.

Proven Effectiveness / Experience Elsewhere: Soakaway pits for roof leader drainage have been
implemented in numerous areas (e.g. Toronto, Lindsay, Maryland, etc.). A study conducted in Lindsay in
1992 indicated that 60% of the 25 pits reviewed were operating as designed.

When compared to rear yard ponding, soakaway pits promote greater recharge (less evapotranspiration)
and provide reduced inconvenience to the homeowner (less surface water ponding). On the other hand
soakaway pits involve greater maintenance and have an uncertain longevity.

Cost Considerations: For new developments, implementation would be relatively inexpensive with
additional cost limited to the excavation and construction of the soakaway pit and extended connection of
the rainwater leader. For existing sites, implementation costs would be considerably higher due to
disruption, damage and restoration of existing finished property features.

Objectives Addressed:

                             Technical Objectives (Terms of Ref.)                           Measure
                                                                                            Addresses
 1.      Achieve healthy aquatic communities
 2.      Reduce fish consumption advisories
 3.      Reduce erosion impacts                                                                  X
 4.      Re-establish natural hydrologic process                                                 X
 5.      Re-establish natural features
 6.      Virtual elimination of toxic contaminants using pollution prevention at source
 7.      Achieve water and sediment objectives in watercourses and waterfront                    X
 8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and             X
         spills
 9.      Improve body contact recreation in rivers and reduce beach closures                     X
 10.     Eliminate aesthetic nuisances                                                           X
 11.     Reduce basement flooding                                                                X
 12.     Reduce sanitary sewer inflow and infiltration                                           X
 13.     Protect life and property from flooding

Opportunities Considerations:
· The option will be assessed in further detail on a subwatershed or catchment area based on new
   development or redevelopment areas and/or physical implementation criteria.




1 - 54     City of Toronto
                                                                          SOURCE CONTROLS


References:
· Ministry of the Environment, “Stormwater Management Planning and Design Manual”, Draft Final
   Report, November 1999, Source Control, Chapter 4.
· Alberta Environmental Protection, Standards and Guidelines Branch, “Stormwater Management
   Guidelines’, Section 8, December 1997.




                                                                          City of Toronto   1 - 55
SOURCE CONTROLS




Backyard Swales
WWFMP Type: Source Controls

Primary Mechanism: Infiltration or filtration

Related WWFMPs: Roadside ditches, grassed swales,
roof leader disconnection, reduced lot grading, soak-away
pits, vegetative filter strips, lot level depressions.

Description: Backyard swales are a specialized form of the
generic grassed swales that have historically been
associated with rural drainage. The backyard swale is
normally located along the rear lot line (hence it is a
communal feature). Backyard swales are used to filter,                Backyard swale to filter, detain or
detain and/or infiltrate stormwater runoff, primarily from                    infiltrate stormwater
pervious areas and rooftops. Swale drainage can be a
useful technique in areas of low grade, if the distance that the water is to be conveyed is not too long.

In areas with good soil infiltration characteristics, this measure contributes towards maintaining the
hydrologic balance (through recharge) and pollutant removal. To a lesser extent, it produces benefits to
erosion control (slowing down runoff) and provides pre-treatment for downstream end-of-pipe controls.
The measure is relatively ineffective in relation to flood control objectives and may in some instances
lead to localized nuisance flooding (during large storms).

In areas where the soils do not support good infiltration, backyard swales act as filters, removing coarse
particulate and providing pre-treatment for downstream controls. As filters they do not contribute
significantly to the hydrologic balance or to erosion control. Swales that rely on filtering rather than
infiltration are generally much less effective as a pollutant removal control.

The application of backyard swales is most useful when they are designed into the development form. In
such designs, the backyard swale can be combined with easements for walkways, lanes, or storm sewer
infrastructure. Application in retro-fit and infill situations is typically not recommended because of the
problems with existing drainage patterns, fencelines and the potential for communal disputes. In general,
related options such as soak-away pits or lot level depressions (where the measure is confined to a single
lot) are recommended in these situations.
Application Requirements: Primarily new development or re-development. Difficult for retro-fit and
infill because of fence lines and existing grading.

Infiltration:
     · New or redevelopment residential area with pervious soils
     · Soils: min infiltration: 15mm/hr;
     · Bedrock/Water Table > 1m;
     · Slope: < 5%

Filtration:
    · New or redevelopment residential area with poor infiltration



1 - 56   City of Toronto
                                                                                   SOURCE CONTROLS


    ·   Bedrock/Water Table > 1m;
    ·   Slope: < 5%

Proven Effectiveness/Experience Elsewhere:

Infiltration:
     · Secondary level of control for pollutant removal, as limited pollutant load accumulates on roof
          tops and pervious areas. Largely ineffective from December to March.
     · Assume 95% pollutant removal for unit area loading rate times ratio of disconnected roof
          imperviousness + pervious area to total site area.
     · Model flow reduction by directing rear roof and pervious area runoff to a pervious zone/block

Filtration:
    · Assume 20% pollutant removal for unit area loading rate times ratio of disconnected roof
         imperviousness + pervious area to total site area.
    · No flow benefits to be modelled

Note: This is not considered to be a stand-alone control option and should be employed as part of a
multi-component approach that uses a series of controls (either at the site level or in conjunction
with conveyance and off-site end-of-pipe controls).

Cost Considerations: No additional cost associated with option when applied in new and redevelopment
situations. Standard municipal practice does not provide a subsidy or other credit for new and
redevelopment (assumes negotiated approach to alternative urban design standards that does not result in
a loss of developable land).

Not typically recommended for retrofit or infill situations.

Objectives Addressed:

                         Technical Objectives (Terms of Ref.)                              Measure
                                                                                           Addresses
 1. Achieve healthy aquatic communities                                                       X
 2 Reduce fish consumption advisories
 3. Reduce erosion impacts                                                                      X
 4 Re-establish natural hydrologic process                                                      X
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source
 7. Achieve water and sediment objectives in watercourses and waterfront                        X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures
 10. Eliminate aesthetic nuisances
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding                                             (careful not to
                                                                                         increase
                                                                                         nuisance
                                                                                         flooding)




                                                                                   City of Toronto   1 - 57
SOURCE CONTROLS


Opportunities Considerations:
· Opportunities identification based on:
      · New development or redevelopment areas;
      · Physical implementation criteria;

·   Matrix-type opportunities assessment by watershed (Step 3B in Assessment Process)

References:
· Ministry of the Environment, Stormwater Management Planning and Design Manual, 2000 Update
   (in press). A draft copy of this document appeared in the Environmental Bill of Rights (EBR)
   registry in early 2000.




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                                                                                       SOURCE CONTROLS




Vegetative Filter Strips
WWFMP Type: Source Controls

Primary Mechanism: Infiltration or filtration

Related SWMPs: Roadside ditches, grassed
swales,      backyard     swales, roof  leader
disconnection, reduced lot grading, soak-away
pits, lot level depressions

Description: Filter strips are engineered
stormwater conveyance systems which treat small
drainage areas. Generally, a filter strip consists
of a level spreader and numerous vegetative
plantings. The level spreader ensures uniform             Vegetative plantings filter out pollutants and
flow over the vegetation.        The vegetative             promote infiltration of the stormwater
plantings filter out pollutants and promote
infiltration of the stormwater.

Filter strips are best implemented adjacent to a buffer strip, watercourse, drainage swale or roadway since
the discharge from a filter strip will be in the form of sheet flow and therefore must be channelled (either
in a sewer, swale system or the receiving watercourse) for subsequent conveyance.

The vegetated strip should be 10 - 20 meters wide in the direction of flow to provide sufficient stormwater
quality enhancement. The ideal slope in a filter strip is < 5 % (1% - 5%). There is a direct relationship
between filter slope and filter length. Shorter filter strip widths (10 m - 15 m) are appropriate for flat
slopes whereas longer filter strips (15 m - 20 m) are required in areas with a higher slope (5% - 10 %)

In areas with good soil infiltration characteristics, this measure contributes towards maintaining the
hydrologic balance (through recharge) and pollutant removal. To a lesser extent, it produces benefits to
erosion control (slowing down runoff) and provides pre-treatment for downstream end-of-pipe controls.
The measure is relatively ineffective in relation to flood control objectives and may in some instances
lead to localized nuisance flooding (in large storms).

In areas where the soils do not support good infiltration, vegetative filter strips act as filters only,
removing coarse particulate and providing pre-treatment for downstream controls. As filters they do not
contribute significantly to the hydrologic balance or to erosion control. Vegetated filter strips that rely on
filtering alone have limited effectiveness for water quality control due to the difficulty of maintaining
sheet flow through the vegetation.

Participation rates and ongoing maintenance of vegetative filter strips are significant concerns in the
application of this type of control. To be most effective, the filter area must be kept relatively “wild” (eg.
longer, thicker vegetation) and can give the impression of being “unkept”. New owners will often reduce
the effectiveness of a filter by “manicuring” the area.

Application Requirements: All development types draining to valleys, ravines, parkland and other open
space (with defined conveyance system – swales or sewers) and with no history of slope stability



                                                                                       City of Toronto   1 - 59
SOURCE CONTROLS


problems. Roof discharge to lawns should not be construed as discharge to a vegetative filter strip (in
order to avoid double-counting).

    ·    Available width: 15 m at slopes < 5%; 20 m at slopes of 5-10 %
    ·    Drainage area < 2 hectares
    ·    Groundwater depth > 0.5 m
    ·    Assume ongoing participation rates of 5, 10, and 25% for screening purposes.

Proven Effectiveness/Experience Elsewhere: In areas with good infiltration characteristics (> 15mm/hr
infiltration rate) this is a secondary level of control for pollutant removal, as limited pollutant load
accumulates on roof tops and pervious areas. Largely ineffective from December to March.

Assume 95% pollutant removal for unit area loading rate times ratio of disconnected roof imperviousness
+ pervious area to total site area, modified to reflect participation rates of 5, 10 and 25%. Model flow
reduction by directing rear roof and pervious area runoff to a pervious zone/block

In areas with poor infiltration this is a tertiary level of control because of limited accumulation combined
with lower effectiveness and lower participation rates.

Assume 20% pollutant removal for unit area loading rate times ratio of disconnected roof imperviousness
+ pervious area to total site area, modified to reflect participation rates of 5, 10 and 25%. No flow
benefits to be modeled

Note: This is not considered to be a stand-alone control option and should be employed as part of a
multi-component approach that uses a series of controls (either at the site level or in conjunction
with conveyance and off-site end-of-pipe controls).

Cost Considerations: No additional cost associated with option for new, infill and redevelopment
situations. Standard municipal practice does not provide a subsidy or other credit for new and
redevelopment. Land owner assumed to implement based on education and landscaping preference.




1 - 60    City of Toronto
                                                                                       SOURCE CONTROLS


Objectives Addressed:

                            Technical Objectives (Terms of Ref.)                                 Measure
                                                                                                 Addresses
    1. Achieve healthy aquatic communities                                                          X
    2 Reduce fish consumption advisories
    3. Reduce erosion impacts                                                                            X
    4 Re-establish natural hydrologic process
    5. Re-establish natural features
    6. Virtual elimination of toxic contaminants using pollution prevention at source
    7. Achieve water and sediment objectives in watercourses and waterfront                              X
    8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
    9. Improve body contact recreation in rivers and reduce beach closures
    10. Eliminate aesthetic nuisances
    11. Reduce basement flooding
    12. Reduce sanitary sewer inflow and infiltration
    13. Protect life and property from flooding

Opportunities Considerations:
· Opportunities screening based on:
      · Physical implementation criteria;
      · Assume that simple flow across a lawn does not constitute a vegetative filter;

·     Preliminary screening (if warranted) based on:
          · Spreadsheet (or equivalent) assessment of overall pollutant removal effectiveness based on
              opportunities, removal effectiveness, and participation rates – define lowest and highest level
              of improvement;

·     Detailed Assessment (if warranted) based on:
         · Modify contaminant removal relationships as appropriate. Detailed assessment of flow and
              conveyance not warranted. (there to assess effects on flows (sewer, baseflow, flow frequency,
              flood flows);
         · Derived assessment (based mostly on contaminant load) for water quality indices.

References:
· Ministry of the Environment, Stormwater Management Planning and Design Manual, 2000 Update
   (in press). A draft copy of this document appeared in the Environmental Bill of Rights (EBR)
   registry in early 2000.




                                                                                       City of Toronto       1 - 61
SOURCE CONTROLS




Stream and Valley Corridor Buffer Strips
WWFMP Type: Source Controls

Primary Mechanism: Infiltration, filtration, shading

Related WWFMPs: Vegetative filter strips

Description: Stream and valley corridor buffer strips are simply natural
areas between development and the receiving waters or habitat areas
(eg. woods, wetlands, etc.) that are to be protected. While buffer strips
are often enhanced or restored through planting initiatives, they are
rarely “engineered” to enhance their stormwater-related functions.
Except where restoration is necessitated by construction or bank
instability problems, stream and valley corridors are normally left alone.
Where possible, municipal maintenance activities (mowing, weed
control, etc.) are minimized within buffer areas.

There are two broad resource management objectives associated with              Grass buffer strips along
buffer strips:                                                                           fields

    ·    the protection of the stream and valley corridor system to ensure their continued ecological form
         and functions
    ·    the protection of vegetated riparian buffer areas within the valley system to minimize the impact
         of development on the stream itself (filter pollutants, provide shade and bank stability, reduce the
         velocity of overland flow)

Although both types of buffers provide only limited benefits in terms of stormwater management, they are
an integral part of overall environmental management for sustainable development. The protection of
stream and valley corridors provides significant benefits in terms of sustaining wildlife migration
corridors, terrestrial and aquatic species food sources, terrestrial habitat, and linkages between natural
areas.

Given the larger scale natural system benefits provided by stream and valley corridors, the required width
of this type of buffer is best defined at the subwatershed plan level. The Toronto Region Conservation
Authority has guidelines for buffer areas. In most cases the necessary buffer areas are already in public
ownership within the City of Toronto (flood plain lands).

Stream and valley corridors are typically important areas for public recreation. They also provide a
desirable location for municipal trunk infrastructure (sewers, roads, pathway networks, end-of-pipe
stormwater controls). Tradeoffs must often be considered in regard to enhancing (eg. intensifying the
density of vegetation) the corridor buffer and using for this infrastructure. In all cases where the corridor
is considered for secondary purposes, an assessment is needed to ensure that its natural functions are
maintained. There will normally be a buffer area within the corridor (usually design to protect the top-of-
bank from erosion or slope failure-related impact) in which no development (either public or private) is
permitted.




1 - 62    City of Toronto
                                                                                       SOURCE CONTROLS


Historically, many smaller watercourses have been replaced by buried storm sewer systems. Today there
are some initiatives under way that would seek to restore these former watercourses (often referred to as
“daylighting”). “Daylighting” is a highly symbolic control option and has strong educational and
publicity values in addition to potential benefits to improving hydrologic response and water quality.
Under most circumstances the current landownership has both physical and infrastructure constraints,
which impose limits on the degree to which restoration can be completed. From a water quality
assessment perspective, “daylighting” proposals should meet implementation criteria similar to that used
for vegetated buffer strips (eg. minimum buffer width/slope requirements).

Application Requirements: None for existing corridors and buffers. Use site-specific information for
“daylighting” proposals. For water quality assessment purposes, daylighted corridors must meet the
following criteria on each side of the watercourse:

·   Available width: 15 m at slopes < 5%; 20 m at slopes of 5-10 %

Proven Effectiveness/Experience Elsewhere: Buffers provide multiple benefits and are an established
and accepted form of environmental management and protection. Water quality benefits (chemical) are
highly variable but can generally be considered to be at a second or third level in terms of effectiveness.
The primary aquatic benefits of natural buffers relate to stream temperatures and food sources.
For existing buffers assume that the effects on water quality, temperature, and flow are accounted for in
the calibration modeling for the existing condition.
In cases where enhancement is proposed (eg. additional planting), temperature assessment, based on
increased shading should be accounted for in the receiving water assessment.

For “daylighting” proposals the hydrologic model should be modified to reflect a change from a sewer to
an open conveyance system. Assume 20% pollutant removal for unit area loading rate for flows directed
to a “daylighted” watercourse if minimum width and slope requirements are met.

Note: This is not considered to be a stand-alone control option and should be employed as part of a
multi-component approach that uses a series of controls (either at the site level or in conjunction
with conveyance and off-site end-of-pipe controls).

Cost Considerations: No additional cost associated with existing corridors. Project specific costs to be
used for “daylighting” proposals.




                                                                                       City of Toronto   1 - 63
SOURCE CONTROLS


Objectives Addressed:

                              Technical Objectives (Terms of Ref.)                             Measure
                                                                                               Addresses
    1. Achieve healthy aquatic communities                                                        X
    2 Reduce fish consumption advisories
    3. Reduce erosion impacts
    4 Re-establish natural hydrologic process                                                      X
    5. Re-establish natural features                                                               X
    6. Virtual elimination of toxic contaminants using pollution prevention at source
    7. Achieve water and sediment objectives in watercourses and waterfront                        X
    8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
    9. Improve body contact recreation in rivers and reduce beach closures
    10. Eliminate aesthetic nuisances
    11. Reduce basement flooding
    12. Reduce sanitary sewer inflow and infiltration
    13. Protect life and property from flooding                                              (careful not
                                                                                             to    increase
                                                                                             nuisance
                                                                                             flooding)

Opportunities Considerations:
· Opportunities screening based on existing conditions:
      · Established flood and fill regulation limits;
      · Extended flood lines;
      · Designated public lands (eg. ESAs).

·     Opportunities screening based on “daylighting” of historic watercourses
         · Use specific proposals where they exist

·     Preliminary screening (if warranted) based on:
          · No assessment required for existing corridors (addressed through calibration for the existing
              condition).

·     Assess “daylighting” opportunities using the criteria specified for Vegetative Filter Strips except for
      participation rate (to be established based on specific project proposal)

·     Detailed Assessment (if warranted) based on:
         · Modify contaminant removal relationships as appropriate. Detailed assessment of flow and
              conveyance, if warranted. Derived assessment (based mostly on contaminant load) for water
              quality indices
References:
· Ministry of the Environment, Stormwater Management Planning and Design Manual , 2000 Update
   (in press). A draft copy of this document appeared in the Environmental Bill of Rights (EBR)
   registry in early 2000.
· Toronto and Region Conservation Authority, Valley and Stream Corridor Management Program
   October 1994




1 - 64      City of Toronto
                                                                                       SOURCE CONTROLS




Bioretention Areas
WWFMP Type: Source Controls

Primary Mechanism: Filtration

Related WWFMPs: Sand and organic/sand filters,
vegetated filter strips

Description: Bioretention areas or biofilters are a
specialized form of the more generic engineered sand
filter class of stormwater control. They operate based on
the same principals and have similar limitations, but they
allow integration with landscaping strategies and tree
planting objectives.
                                                                Bioretention with landscaped surface to
All types of filters are a relatively new type of SWMP                     treat stormwater
control in Ontario. They have been used extensively in
parts of the United States for the past 10 years with good success (Metropolitan Washington Council of
Governments, 1992). Filters are generally intended for small drainage areas (< 5 ha). They are a water
quality SWMP and have no practical application for water balance, erosion or quantity control. However,
they can be designed to be part of the storm sewer system and thus can be combined with measures such
as rooftop, parking lot or super-pipe storage (for quantity control). While most applications filters
discharge to the storm sewer system, direct discharge to a watercourse is possible, where there is
sufficient topographic relief.

Filtration systems can be incorporated into most parking lot areas or commercial sites. The surface of the
Bioretention area can be landscaped using trees, shrubs and riverstone or turf and integrated as an amenity
within the overall landscape for the development. Biofilters can also be combined with hard surface
landscaped areas, such as courtyards, walkways and patios.

Bioretention areas, as with all filters, have both positive and negative attributes. They are effective in
removing pollutants, resistant to clogging (if pretreatment is provided) and are generally easier and less
expensive to construct/retrofit than infiltration trenches. As with all filter systems, long term maintenance
normally requires removal of all or some of the sand filter media. In the case of bioretention areas, this
maintenance has the added disadvantage of the need to uproot and replant the vegetation that has
established itself. Subsurface sand filters are often preferred over bioretention areas (in retrofit and even
new commercial applications) because of the planning required regarding the required number of parking
spaces (biofilters reduce the number of spaces, while conventional underground filters can accommodate
spaces).

Bioretention areas are generally subject to the same cold-weather problems as surface filters and
infiltration devices. Unlike infiltration devices, filters commonly receive runoff from parking areas and
roads that are subject to intense sanding and salting. As a result, they are particularly susceptible to
clogging. Pretreatment is essential to avoid regular problems in this regard. For bioretention areas,
runoff should be conveyed through a grass strip or swale (at least 5 m in length) prior to entering the filter
area.




                                                                                       City of Toronto   1 - 65
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Experience with filters in Ontario is limited in terms of their use as stormwater quality devices.
Pretreatment and longevity are critical factors that may vary from design to design. The most recent
update to the MOE SWMP manual recommends that they be used for pretreatment, post-treatment, and in
terms of water quality control that they be implemented as part of a multi-component approach. In a
multi-component approach there are a series of stormwater quality measures. None are considered to be
sufficient on their own, but in series, they may be expected to provide a moderate to high level of water
quality improvement. SWMPs used in a multi-component approach often includes oil/grit separators,
soakaway pits, sand and bioretention filters, vegetated filter strips, or enhanced grassed swales.

Application Requirements: Lot level developments with high levels imperviousness. Normally
characterized by connection to a storm sewer conveyance system and/or soils with poor infiltration
characteristics. Beneficial control for commercial/industrial applications.

Contributing drainage area < 5 hectares.
Depth to bedrock, water table > 3.5m.

Discharge to valleys, ravines, parkland and other open space (with defined conveyance system – swales
or sewers) permissible if physically feasible and no history of slope stability problems

Consider in all commercial and industrial areas, using suggested participation rates (to reflect both
subsidy levels and other limitations such as available space).

Note: application may be limited by benefit-cost comparison to alternative forms of treatment

Proven Effectiveness/Experience Elsewhere: Limited Ontario experiences, especially in cold weather
and under salting conditions. U.S. experience: highly effective (similar to infiltration techniques) if
pretreatment is used and if the facility is adequately sized and properly maintained.

Assume 85% pollutant removal for unit area loading rate for storms up to 15 mm. Reduce effectiveness
to zero (assuming by-pass) for larger storms. Modify to reflect participation rates of 10, and 25 and 50%
for retrofit situations (based on 33, 67 and 100% subsidy). No flow benefits to be modeled

Note: This is not considered to be a stand-alone control option and should be employed as part of a
multi-component approach that uses a series of controls (either at the site level or in conjunction
with conveyance and off-site end-of-pipe controls).

Cost Considerations: For new or redevelopment applications there would be no additional cost
associated with option. The land owner is assumed to implement based on normal approval process. For
retrofit conditions, subsidy level will be strongly linked to participation rate.




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Objectives Addressed:

                            Technical Objectives (Terms of Ref.)                                Measure
                                                                                                Addresses
    1. Achieve healthy aquatic communities                                                         X
    2 Reduce fish consumption advisories
    3. Reduce erosion impacts
    4 Re-establish natural hydrologic process
    5. Re-establish natural features
    6. Virtual elimination of toxic contaminants using pollution prevention at source
    7. Achieve water and sediment objectives in watercourses and waterfront                              X
    8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
    9. Improve body contact recreation in rivers and reduce beach closures
    10. Eliminate aesthetic nuisances                                                                    X
    11. Reduce basement flooding
    12. Reduce sanitary sewer inflow and infiltration
    13. Protect life and property from flooding

Opportunities Considerations:
· Opportunities screening based on:
      · Commercial or industrial land use

·     Preliminary screening (if warranted) based on:
          · Spreadsheet (or equivalent) assessment of overall pollutant removal effectiveness based on
              opportunities, removal effectiveness, and participation rates – define lowest and highest level
              of improvement;

·     Detailed Assessment (if warranted) based on:
         · Modify contaminant removal relationships as appropriate. Detailed assessment of flow and
              conveyance not warranted. (there to assess effects on flows (sewer, baseflow, flow frequency,
              flood flows);
         · Derived assessment (based mostly on contaminant load) for water quality indices

References:
· Ministry of the Environment, Stormwater Management Planning and Design Manual, 2000 Update
   (in press). A draft copy of this document appeared in the Environmental Bill of Rights (EBR)
   registry in early 2000.




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Rooftop Storage and Rooftop Gardens
WWFMP Type: Source Controls

Primary Mechanism: Storage and/or
Evapotranspiration

Related WWFMPs: Storage only: superpipes,
parking lot storage, inlet controls (roadway
storage)
Gardens: Urban forest, enhanced vegetation

Description: Flat building roofs can be used to
store the rain that falls on them and to reduce
peak flow rates of runoff to storm sewer systems.
Rooftop storage has been used for several
decades as a peak flow (quantity) control. There
are few water quality, erosion control or water      Rooftop vegetation atop Toronto City Hall
balance-type benefits achieved by utilizing this
type of storage on building roofs. However, site servicing and storm drainage costs can be reduced
through reduced downstream storm sewer sizes and such systems contribute to flood control objectives.
Rooftop storage is economical when addressed at the building design stage and requires little extra cost
during construction

Traditional rooftop storage is applicable to large flat commercial and industrial rooftops, and in some
cases residential apartment/condominium development. Peaked roofs offer few opportunities for storage.
Rooftop storage is widely applied for infill development scenarios to mitigate the need for downstream
storm sewer size increases. This control storage is highly effective in reducing downstream peak flow
rates. The volume of storm runoff to the sewer system is not reduced as discharge occurs over a much
longer duration.

Roof top gardens (an extension of the traditional storage techniques) are a relatively recent innovation in
the field of stormwater management. They are typically designed to capture runoff from smaller storms
than traditional rooftop storage systems. They are therefore more oriented towards providing water
quality, erosion and water balance-type benefits. Roof top gardens may be as simple as installing a layer
of soil medium and establishing turf to create a sodded roof which retains water in the soil medium and
provides filtration. They can also be more elaborate, involving a fully landscaped area with trees, shrubs,
gardens, fountains, seating areas and other outdoor amenities. At both extremes of the range, roof top
garden stormwater management is an integral design objective. The range of plants suitable for use in
roof top landscapes is limited by the extremes of microclimate of the roof top setting, including high
wind, low winter temperature due to lack of ambient heat which is retained in the ground in at-surface
situations, and drought. As a result, alpine or sub-alpine species are well suited to roof top applications.
In more elaborate schemes, infrastructure such as irrigation systems, increased insulation and venting
from interior heat sources can be employed to overcome limitations imposed by adverse microclimate
conditions. Roof top gardens have been used extensively and successfully in Europe and their
performance is well documented.




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                                                                                   SOURCE CONTROLS


Application Requirements: Primarily new development, infill or re-development involving structures
with flat roofs. Difficult for retro-fit because of structural load requirements and potential cost of
building modifications (eg. piping etc.). Consider for new, infill and redevelopments in designated land
use areas, based on suggested participation rates.

Proven Effectiveness/Experience Elsewhere:

Rooftop Storage
Traditional rooftop storage is an effective peak flow control and is accepted by the Toronto and Region
Conservation Authority (TRCA) as part of stormwater management strategies (for quantity control).
There is no benefit for pollutant removal, erosion or water balance.

Rooftop Gardens
For rooftop gardens effectiveness will be design-dependent effectiveness.          There is little direct
experience regarding the benefits of this sub-option. TRCA has no specific policy regarding water quality
“credit” for this option. Assume 45% pollutant removal (90% capture over 50% of roof area) for
applicable participation rates. Model runoff using increased evapotranspiration or depression storage,
based on 50% of roof area and participation rates.
Note: This is not considered to be a stand-alone control option and should be employed as part of a
multi-component approach that uses a series of controls (either at the site level or in conjunction
with conveyance and off-site end-of-pipe controls).

Cost Considerations: No additional cost associated with option when applied in new, infill and
redevelopment situations (assumes extra costs are part of the normal stormwater requirements or are
based on lifestyle/amenity considerations). Standard municipal practice does not provide a subsidy or
other credit for new and redevelopment.

Objectives Addressed:

                         Technical Objectives (Terms of Ref.)                               Measure
                                                                                            Addresses
 1. Achieve healthy aquatic communities
 2 Reduce fish consumption advisories
 3. Reduce erosion impacts                                                                           X
 4 Re-establish natural hydrologic process                                                           X
 5. Re-establish natural features
 6. Virtual elimination of toxic contaminants using pollution prevention at source
 7. Achieve water and sediment objectives in watercourses and waterfront                             X
 8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9. Improve body contact recreation in rivers and reduce beach closures
 10. Eliminate aesthetic nuisances
 11. Reduce basement flooding
 12. Reduce sanitary sewer inflow and infiltration
 13. Protect life and property from flooding                                                         X

Opportunities Considerations:
· Opportunities screening based on:
      · New development, infill or redevelopment areas for commercial, industrial and high density
          residential uses;



                                                                                   City of Toronto       1 - 69
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·   Preliminary screening (if warranted) based on:
        · Rooftop storage: limit benefit to flooding (no erosion, water balance or water quality) for
            storms > 25 mm.
        · Rooftop gardens: Spreadsheet (or equivalent) assessment of overall pollutant removal
            effectiveness based on opportunities and removal effectiveness – define highest level of
            improvement;

·   Detailed Assessment (if warranted) based on:
       · HSPF modeling to assess effects on flows (sewer, baseflow, flow frequency, flood flows);
       · Derived assessment for aquatic indices, erosion indices, water quality indices

References:
· Ministry of the Environment, Stormwater Management Planning and Design Manual, 2000 Update
   (in press). A draft copy of this document appeared in the Environmental Bill of Rights (EBR)
   registry in early 2000.
· www.interlog.com/~rooftop




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Enhanced Yard Vegetation and
Rain/Storm Gardens
WWFMP Type: Source Controls

Primary Mechanism: Filtration, Infiltration and/or
Evapotranspiration

Related WWFMPs: Filler strips, buffers, urban forest

Description: Reduction of stormwater volumes entering
the storm sewer system can be accomplished through a
variety of on-site and off-site management practices,
such as downspout disconnection with diversion to
rainbarrels, ponds and infiltration areas. On-site
management generally includes creating permanent or
temporary ponding areas to hold stormwater for
infiltration into the soil. The approach can be improved        Rain/storm garden to decrease runoff and
considerably through greater use of vegetation to                         encourage infiltration
promote evapotranspiration, in addition to infiltration
and evaporation to the atmosphere. Landscaping and plants suitable to the site conditions are used to
facilitate absorption and transpiration. At the site level, the planting of a storm garden designed to make
use of intercepted rainfall and runoff provides many benefits related to restoring the natural hydrologic
cycle.

A specialized form of vegetation enhancement is the storm garden or rain garden. The term refers to a
constructed depressional area that is used as a landscape tool to improve water quality. It combines the
storage aspects of rain barrels and roof discharge to lawns, with the water re-use attributes of rooftop
gardens or bioretention filters. The storm garden area provides infiltration, water storage and
evapotransiration for sheet flow that is precipitation generated. Creation of a rain garden can occur on
many levels and in the more sophisticated application may include intermediate storage, trickle irrigation
systems, and aquatic gardens (with or without recirculating pumps).

Rain gardens are suitable for any land use situation, (residential, commercial and industrial) although
problems may arise from areas receiving road salt contamination, in which special hardy plants must be
utilized. A rain gardens purpose is to minimize the volume and quality of water entering conventional
storm drains and nearby streams. (Source: Virginia Department of Forestry).

In addition to the enhanced use of vegetation in conjunction with lot-scale source controls, vegetation
should be considered as an important functional component in the design of non-structural SWMPs such
as ponds, wetlands, filter strips and bioretention facilities

Application Requirements: The use of enhanced vegetative plantings is considered to be part of the
design of other control options or is addressed under the Urban Forest control option. It can be applied
under conditions similar to those specified for Urban Forest. It does not require separate assessment as an
individual control option.




                                                                                     City of Toronto   1 - 71
SOURCE CONTROLS


Proven Effectiveness/Experience Elsewhere: In addition to the capability to enhance the performance
of stormwater facilities in terms of pollutant removal through processes such as filtering and uptake, plant
material is an effective tool to achieve the following:

The Stabilization of Banks, Shoreline and Slopes: The rooting systems of many species of trees, shrubs
and herbaceous plants effectively binds soils to establish a layer that is resistant to erosion. Planting
schemes that combine a suite of plant species selected for their unique and complementary rooting
characteristics are typically most effective in providing long term stability.

Mitigation of Temperature Increases Through Shading: The strategic location of deciduous and
coniferous trees along the edges of a pond, channel or wetland can assist in mitigating undesirable
increases in water temperature. In addition, vegetation can contribute to the maintenance of dissolved
oxygen levels by inhibiting the growth of algae.

Deterrence of Geese: The establishment of a dense band of woody vegetation around the perimeter of a
pond or wetland is the most effective means to deter undesirable species of waterfowl from colonizing
and contaminating facilities which have a permanent pool.

Provision of Barriers to Mitigate Public Access: Thickets of thorn bearing shrubs and trees, and twining
vines can be combined to create an impenetrable barrier to deter the public from accessing pond areas,
steep slopes and other areas which are deemed potentially sensitive or hazardous.

Enhancement of Linkages: The establishment of diverse communities of plants in conjunction with a
stormwater management pond can contribute to the establishment of linkages between natural wooded
areas, providing terrestrial habitat benefits at a larger scale.

Provision of Aesthetic Benefits: Vegetation can be utilized to create visual buffers, enhance views and
contribute to the establishment of a unique character for a development. Vegetation is one of the most
effective tools to blend a SWMP into its surroundings from a visual perspective.

Additional Benefits: Vegetation can also be utilized in the design of SWMPs to achieve the following:

          Intercept rainfall
          Filter out coarse sediments
          Trap and accumulate floatables
          Reinforce and maintain the integrity of spreaders, weirs and retaining walls
          Intercept airborne pollutants
          Impede colonization by undesirable invasive species
          Conceal fencing and structures.

Cost Considerations: No additional cost associated with option (assumed to be part of design cost and
private landscaping).




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                                                                                   SOURCE CONTROLS


Objectives Addressed:

                           Technical Objectives (Terms of Ref.)                              Measure
                                                                                             Addresses
    1. Achieve healthy aquatic communities                                                      X
    2 Reduce fish consumption advisories
    3. Reduce erosion impacts                                                                        X
    4 Re-establish natural hydrologic process                                                        X
    5. Re-establish natural features                                                                 X
    6. Virtual elimination of toxic contaminants using pollution prevention at source
    7. Achieve water and sediment objectives in watercourses and waterfront                          X
    8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
    9. Improve body contact recreation in rivers and reduce beach closures                           X
    10. Eliminate aesthetic nuisances                                                                X
    11. Reduce basement flooding
    12. Reduce sanitary sewer inflow and infiltration
    13. Protect life and property from flooding

Opportunities Considerations:
· These measures are incorporated in the bundling analysis. Therefore modelling will be performed on
   the effectiveness and unit costs will be derived.

References:
· Ministry of the Environment, Stormwater Management Planning and Design Manual , 2000 Update
   (in press). A draft copy of this document appeared in the Environmental Bill of Rights (EBR)
   registry in early 2000.
· City of Toronto, by David Orsini and Associates, Prepared for the Rain Water Diversion Program,
   City Works Services, Development of Brochure Information for Storm Gardens. December 1997.
· Useful descriptive material and photographs of rain gardens can be found at Virginia Department of
   Forestry website (www.dof.state.va.us/site_index.html).




                                                                                   City of Toronto       1 - 73
SOURCE CONTROLS




Urban Forest
WWFMP Type: Source Controls

Primary Mechanism: Interception/evapotranspiration,
infiltration or filtration

Related WWFMPs: Bioretention areas, vegetative filter
strips, buffer strips, enhanced vegetation and storm
gardens, rooftop gardens:

Description: The practice of planting trees in urban areas
to achieve a high level of tree canopy cover has multiple
benefits, including stormwater flow reduction. Trees in
our urban environment provide numerous benefits
relating to maintaining the natural hydrologic cycle,                   Urban forest
including capturing an initial portion of runoff, sheltering
natural areas from erosion and increasing infiltration and evapotranspiration (water expelled to the
atmosphere).

Methods developed by American Forests can quantify the hydrologic benefit of existing trees and of
enhanced tree cover in the urban ecosystem. The method called “urban ecological analysis” is carried out
by a software package called CITYgreen, which utilizes computer maps of an area in a geographical
information system (GIS). The analysis then can be used to justify additional investments in tree planting.
American Forests recommend a goal for tree canopy cover in urban areas of 40%, broken down into 15%
for business districts, 25% for urban residential, and 50% for suburban.

American Forests applied the CITYgreen software to the City of Milwaukee. The current tree canopy of
18% was calculated to be worth $305 million, in terms of the equivalent storage required to capture the
flow from a two-year storm (it was estimated that this water volume would be captured by the existing
tree canopy). If Milwaukee increased its canopy cover to the goal of 40%, additional stormwater benefits
of $202 million were estimated. In addition, an air pollution reduction benefit of $18 million was
estimated for the increased canopy.

Tree planting can be encouraged for individual residents and institutions, school boards, commercial and
industrial sites. Public participation in tree planting programs for vacant public lands are a good way to
raise awareness and achieve increased tree cover.

Trees provide benefits in energy conservation and reduction in the production in greenhouse gases.
Aesthetics and wildlife habitat is improved. The goal of environmental sustainability of a community is
enhanced. Flow reduction benefits include: reduced stormwater hydraulic effects in-stream, including
flooding and erosion; reduced overflows and treatment costs for combined sewer conditions; and reduced
need for stormwater retention systems (storage ponds or tunnels).

Programs to encourage public involvement in tree planting programs have usually been successful.
Involvement of community volunteers, students, service clubs and scouting groups are encouraged.




1 - 74   City of Toronto
                                                                                   SOURCE CONTROLS


Application Requirements: All types of development with pervious area < 50% covered by canopy and
overall site imperviousness < 70%. Differentiate between public property (road allowance) and private
property.

Assume opportunities based on 25% and 50% increase in canopy over existing levels (typical existing
levels derived from GIS/air photos) up to a maximum of 75% coverage of pervious area. Modify this by
participation rates of 20, 40 and 60% for public lands and 10, 20 and 30% for private lands.

Exclude park areas and institutional lands used as playing fields.

Proven Effectiveness/Experience Elsewhere: The many positive benefits of urban forests are generally
recognized. Flow interception benefits can be calculated theoretically. It should be recognized that
increases in canopy cover may reduce infiltration (especially in areas of sandy soils) and may therefore
have negative impacts on groundwater quantities and baseflow. Also the theoretical shift to greater
evapotranspiration is offset to some extent by a reduction in simple evaporation.

Limitations will exist both within road allowances and on private property because of concerns for
interference with existing infrastructure (sewers, gas lines, cables etc.).

For water quality benefit assessment purposes assume unit load reduction proportional to increases in
estimated interception.

Model flow reduction by altering interception, storage and evapotranspiration parameters.

Note: This is not considered to be a stand-alone control option and should be employed as part of a
multi-component approach that uses a series of controls (either at the site level or in conjunction
with conveyance and off-site end-of-pipe controls).

Cost Considerations: No additional cost associated with new, infill or redevelopment projects (assumed
to be part of the stormwater management plan).




                                                                                   City of Toronto   1 - 75
SOURCE CONTROLS


Objectives Addressed:

                                Technical Objectives (Terms of Ref.)                          Measure
                                                                                              Addresses
    1. Achieve healthy aquatic communities                                                       X
    2 Reduce fish consumption advisories
    3. Reduce erosion impacts                                                                     X
    4 Re-establish natural hydrologic process                                                     X
    5. Re-establish natural features                                                              X
    6. Virtual elimination of toxic contaminants using pollution prevention at source
    7. Achieve water and sediment objectives in watercourses and waterfront                       X
    8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
    9. Improve body contact recreation in rivers and reduce beach closures
    10. Eliminate aesthetic nuisances
    11. Reduce basement flooding
    12. Reduce sanitary sewer inflow and infiltration                                          Potential
                                                                                               negative
                                                                                                impact
    13. Protect life and property from flooding

Opportunities Considerations:
· Opportunities screening based on:
      · Lot size, pervious area available;

·     Preliminary screening (if warranted) based on:
          · Spreadsheet/GIS (or equivalent such as CITYgreen software) assessment of overall flow
              reduction benefit. For preliminary assessments (using spreadsheet approach) assume
              modified water balance for small storms (< 10 mm) in which there is a transfer from the
              groundwater component to the evapotranspiration component proportional to the increase in
              canopy. For medium-type storms (10-25 mm) reduce surface runoff from pervious areas by
              an amount proportional to the increase in canopy over the pervious area and split 50-50
              between groundwater and evapotranspiration components. For larger storms, use the results
              generated for medium storms, ignoring any extended benefits for the extra volume of runoff
              (eg. assume interception capacity is used up and soil is saturated).
          ·      Translate to pollutant removal benefit by reduction in unit area loads, opportunities, and
                 participation rates – define lowest and highest level of improvement;

·     Detailed Assessment (if warranted) based on:
         · Modify contaminant removal relationships as appropriate. Modify pervious area parameters
              such as interception/evapotranspiration to assess flow reduction benefits.
         · Derived assessment (based mostly on contaminant load) for water quality indices

References:
· The State of Our Urban Forest: Assessing Tree Cover and Developing Goals, Sept. 1997American
   Forests, PO Box 2000, Washington DC 20013. Website: www.amfor.org
· Brochures - Project Green,.477 Pelissier Street, Suite 7, Windsor Ont, Canada N9A 4L2; Website:
   www.greencanada.agora.ca




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Oil/Grit Separators




                                   Oil/grit seperator section view

WWFMP Type:              Source Controls

Primary Mechanism: Sedimentation, Phase Separation

Related WWFMPs: Pretreatment Measures (swales, filter strips, sand filters);
Source/End-of-pipe (filters, ponds)

Description: Oil/grit separators (OGS) are used to trap and retain oil and/or sediment in detention
chambers, usually located below ground. They operate based on the principles of gravity-based
sedimentation for the grit, and phase separation for the oil. There is minimal attenuation of flow in
oil/grit separators since they are not designed with extended detention storage. Like filters, they typically
have no infiltration capability.

Separators may be used as spill controls, pretreatment devices or as a source/end-of-pipe controls (as part
of a multi-component approach). They are most typically used for small sites but sizing and design are
dependent on the function they are to fulfil (as a spill control or pretreatment device, or as part of a multi-
component stormwater quality control system). There have been numerous applications of OGS since the
early 1990’s and there are a variety of both proprietary and non-proprietary oil/grit separators on the
market ranging from chambered designs to manhole-types.

Oil/grit separators are typically used for small drainage areas (< 2 hectares) and generally form part of the
underground storm sewer infrastructure. Their use is typically not constrained by space considerations,
bedrock or groundwater levels or soil conditions (although they have foundation bedding requirements
similar to manholes and underground tanks).

As a spill or grit control, they are particularly well suited to conditions where space is constrained. Since
the majority of spills are small in volume and are not weather dependent, separators provide an effective
means of controlling potentially serious problems. Oil/grit separators are beneficial for industrial and
commercial sites with a higher risk of spills, and large parking areas or transit facilities where there is a
concern for either spills or grit build-up. OGS are also often used to provide an inspection access as part




                                                                                        City of Toronto   1 - 77
SOURCE CONTROLS


of a storm sewer discharge control program (eg. sewer use by-law). Typical special purpose applications
include:

·   automobile service station parking areas;
·   selected areas at airports;
·   industrial or commercial loading areas;
·   areas susceptible to spills of material lighter than water (bus depots, transfer stations);
·   inspection structures for private industrial or commercial sites that drain to the municipal sewer
    system.

In recent years there have been many refinements to existing designs of oil/grit separators and new
designs have come to market. Both proprietary interests and government agencies have conducted
research and monitoring of many of the devices. The reported results have been quite variable (both
excellent and very poor) and appear to be highly dependent on study design and sizing of the device,
relative to the contributing drainage area and the magnitude of runoff encountered during the study
period. It is noteworthy that a key factor in assessing the performance of OGS is the level at which by-
pass occurs. As with filter-type SWMPS, by-pass should not occur during a 15 mm, 4 hour design event,
unless the by-pass is routed to another treatment element in a multi-component system.

At this time, it continues to be recommended that oil/grit separators be used primarily for the purposes of
spill control, pretreatment or, in the case of stormwater quality control, that they be implemented as part
of a multi-component approach. In a multi-component approach a number of stormwater quality
measures are employed, in series. None of the measures are considered to be sufficient on their own, but
in series, they may be expected to provide a moderate to high level of water quality improvement.
SWMPs used in a multi-component approach often include oil/grit separators, sand and bioretention
filters, vegetated filter strips, or enhanced grassed swales.

Application Requirements: Primarily used for high imperviousness land uses in all development types
(new, infill, retrofit or re-development) where storm sewer infrastructure exists. Especially useful at
commercial and industrial sites where there is a potential for spills or excessive grit accumulation.

Consider as a spill control in new, retrofit, infill and redevelopment for commercial and industrial
developments. Consider as part of a multi-component approach for stormwater quality control new, infill
and redevelopments for commercial and industrial developments.

Drainage area < 2 hectares (multiple devices may be used for larger sites).

Storage for a 15 mm 4-hour design storm when used as a stormwater quality control (not required for
pretreatment or spill control functions).

Proven Effectiveness/Experience Elsewhere: Effective for spill control, nuisance oil/grit build-up and
pretreatment. When used as a spill control measure, assume 95% reduction of loading rates for oils from
site.

Reported effectiveness variable as a stormwater quality control. Assuming the storage required to prevent
by-pass is sufficient, a removal rate of 60% is utilized for solids-associated parameters.

Note: This is not considered to be a stand-alone control option and should be employed as part of a
multi-component approach that uses a series of controls (either at the site level or in conjunction
with conveyance and off-site end-of-pipe controls).



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                                                                                      SOURCE CONTROLS




No modeling for flow required.

·     Cost Considerations: Various types of OGS are available through different manufacturers. Costs are
      variable and dependent on both the application and the product selected.

Objectives Addressed:

                           Technical Objectives (Terms of Ref.)                                Measure
                                                                                               Addresses
    1. Achieve healthy aquatic communities                                                        X
    2 Reduce fish consumption advisories
    3. Reduce erosion impacts
    4 Re-establish natural hydrologic process
    5. Re-establish natural features
    6. Virtual elimination of toxic contaminants using pollution prevention at source
    7. Achieve water and sediment objectives in watercourses and waterfront                         X
    8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
    9. Improve body contact recreation in rivers and reduce beach closures
    10. Eliminate aesthetic nuisances                                                               X
    11. Reduce basement flooding
    12. Reduce sanitary sewer inflow and infiltration
    13. Protect life and property from flooding

Opportunities Considerations:
· Opportunities screening based on:
      · Land Use (all types of commercial/industrial development for spill control)
      · Exclude existing development (eg. retrofits) for non-spill control) and all types of residential
          development (for new, infill and re-development).

·     Preliminary screening (if warranted) based on:
          · Spreadsheet (or equivalent) assessment of overall pollutant removal effectiveness based on
              spill (oil reduction) and stormwater removal effectiveness – define highest level of
              improvement;

References:
· Ministry of the Environment, Stormwater Management Planning and Design Manual, 2000 Update
   (in press). A draft copy of this document appeared in the Environmental Bill of Rights (EBR)
   registry in early 2000.




                                                                                      City of Toronto   1 - 79
SOURCE CONTROLS




Superpipes
WWFMP Type: Source Controls

Primary Mechanism: Storage, Peak Flow Reduction

Related WWFMPs: Parking lot storage, rooftop
storage, rear yard storage, in-line/off-line storage.

Description: A superpipe is a special in-line/off-line
storage device, which is classified as an “at source”
CSO alternative. A superpipe is an underground storage
device that is created using pre- manufactured pipe
(usually 1800 mm or larger, due to cleaning
considerations) and an orifice plate or a small diameter
outlet pipe that restricts the rate of discharge. As inflow
rates are much larger than the outflow rates, runoff is             Schematic of an outlet controlled
detained within the pipes. Generally, detention times                          superpipe
are in the order of a few hours. Superpipes provide an
alternative to rooftop storage or surficial parking lot storage where these alternatives are infeasible (for
structural or architectural reasons) or undesirable (eg. level of service). Land requirements for superpipes
are generally small while material costs are high when compared to traditional rooftop or surface storage
facilities.

Superpipes are a quantity control when applied in isolation. There are marginal water quality benefits as
only some of the coarser sediment particles will settle out. Generally, superpipes are utilized for small
development sites where there is insufficient surface space to construct detention facilities. Standards to
design and construct superpipes are defined by the local municipality or township.

Superpipes can be used in combination with water quality controls such as filters and oil/grit separators.
The flow restriction provided by the superpipe system prevents frequent overflow or by-pass and
therefore enhances the effectiveness of the water quality control.

Application Requirements: Superpipes may be applied for all types of development where they can be
can be easily excavated if required. Superpipes should not be constructed under structures. In residential
uses, superpipes are normally constructed within the road allowance and are usually a retrofit option.
They are typically used in existing residential areas where basement flooding is a problem. In
commercial or industrial areas, they are most often placed below parking lots. As such they may be
applied to all types of development. In retrofit situations however, high subsidies are normally required
because of the high cost of the option.

Physical application requirements include depths to bedrock or the water table of greater than 3.5 m
(minimum pipe size, plus frost cover).

Proven Effectiveness/Experience Elsewhere: Superpipes are very effective in reducing site peak flow
rates and can be modelled explicitly. Superpipes do not significantly improve water quality unless
combined with water quality devices such as filters or oil/grit separators. Special maintenance
considerations are required for cleaning.



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Cost Considerations: For new, infill or redevelopment assume no increased cost (proponent pays as part
of the normal stormwater management plan costs). Standard municipal practice does not provide a
subsidy or other credit for new and redevelopment.

Objectives Addressed:

                         Technical Objectives (Terms of Ref.)                             Measure
                                                                                          Addresses
    1. Achieve healthy aquatic communities
    2 Reduce fish consumption advisories
    3. Reduce erosion impacts
    4 Re-establish natural hydrologic process
    5. Re-establish natural features
    6. Virtual elimination of toxic contaminants using pollution prevention at source
    7. Achieve water and sediment objectives in watercourses and waterfront
    8. Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and
    spills
    9. Improve body contact recreation in rivers and reduce beach closures
    10. Eliminate aesthetic nuisances
    11. Reduce basement flooding                                                               X
    12. Reduce sanitary sewer inflow and infiltration
    13. Protect life and property from flooding                                                X

Opportunities Considerations:
· Opportunities screening based on:
      · Land Use (new, infill and redevelopment applications of commercial/industrial development;
          retrofit restricted to areas experiencing basement flooding).
      · Depth to bedrock or water table > 3.5m

·     Preliminary screening (if warranted) based on:
          · Spreadsheet (or equivalent) assessment of overall flow reduction effectiveness. Lump with
              rooftop and parking lot storage options.

References:
· Ministry of the Environment, Stormwater Management Planning and Design Manual, 2000 Update
   (in press). A draft copy of this document appeared in the Environmental Bill of Rights (EBR)
   registry in early 2000.




                                                                                   City of Toronto   1 - 81
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Ex-Situ Biological Leachate Treatment
Technologies
Remediation Type: Source Controls

Primary Mechanism: Aerobic and Anaerobic degradation

Related WWMPs: N/A

Description: Leachate generated from municipal landfills consist of numerous constituents, including
organic strength (BOD, COD), ammonia, heavy metals (i.e. iron, zinc, lead, and copper), phosphorus, pH,
and conservative ions (i.e. chloride, sodium, sulphate). As such, various remedial alternatives will be
required to treat landfill leachate.

The major focus of biological treatment is the reduction of BOD levels. Biological treatment is essential
where concentrations of BOD exceed 50 mg/L. In addition to removal of BOD5, biological treatment will
assist with suspended solids removal by sedimentation, ammonia and organic nitrogen by biouptake, and
metals removal by biosorption and precipitation as oxides and carbonates.

There are a number of aerobic biological treatment approaches including lagoons, activated sludge
facilities, rotating biological contactors (RBC) and trickling filters. These alternatives all operate on the
same principle of microorganisms acting on organic matter in the presence of oxygen. The feature that
differentiates the processes is whether the microorganisms are in suspension or fixed to a media.

Aerated lagoons or ponds are used when the biomass is in suspension. The lagoons are controlled by a
series of aerators (mechanical or diffuser). The diffused air can be used to create mixing as well as to
supply oxygen. The effluent in these treatment systems will contain a large amount of suspended solids.

Activated sludge plants are used when the biomass is in suspension. The detention time in activated
sludge plants can be considerably shorter than in aerated lagoons since the bacteria levels are 3 to 5 times
higher and can be controlled through recirculation. This is accomplished by the use of a settling tank
following the aeration tank. In addition to reducing the BOD5 concentrations, activated sludge plants can
significantly nitrify ammonium. The reduction of nitrogen becomes more important with older landfills
as nitrogen levels increase with age of the leachate.

A RBC unit is a fixed-film biological process in which the biomass accumulates on rotating disks. A
RBC unit will tolerate hydraulic or chemical shock loadings much better than suspended growth process
such as aerated lagoons or activated sludge plants. However, RBC units tend to clog with calcium
deposits, which prevent biomass growth. As a result, pre-treatment with NaOH to raise the pH and
precipitate out the metals is commonly applied before it enters the RBC unit. The air supply takes place
naturally in RBC units. The rotating contactor is partly in the air and partly in the water while rotating.
RBC units consume low amounts of energy. However, leachates with high organic levels limit the
treatment process as the precipitates and/or biomass will clog the system and/or may not supply sufficient
oxygen to maintain the aerobic conditions. Fixed film reactors are more effective in nitrification
processes.

Trickling filters are used where the biomass is fixed to the media. They use a fixed surface such as rocks
as the media on which the biomass grows and provide a discontinuous trickling of the water being treated,



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over the biomass. The air supply takes place naturally for trickling filters. The air vents through a
trickling filter from the bottom to the top. This process consumes low amounts of energy. However,
leachates with high organic levels limit the treatment process as the precipitates and/or biomass will clog
the system and/or may not supply sufficient oxygen to maintain the aerobic conditions. Fixed film
reactors are more effective in nitrification processes.

A sequencing batch reactor (SBR) is a fill-and-draw activated sludge treatment system. The unit
processes involved in the SBR and conventional activated sludge processes are identical. Aeration and
sedimentation, or clarification, are carried out in both systems. However, in conventional plants the
processes are carried out simultaneously in separate tanks, whereas in an SBR operation the processes are
carried out sequentially in one tank.

SBRs typically have five steps in common that are carried out sequentially as follows: (1) fill, (2) react
(aeration), (3) settle (sedimentation/ clarification), (4) draw (decant), and (5) idle. Sludge wasting
generally occurs in the settle or idle phases. Some of the main advantages of a SBR system over a
conventional activated sludge process include the following:
· the SBR process is very flexible and specific treatment objectives (e.g. nutrient control) can be
    achieved by modifying the application and duration of mixing and aeration in each phase;
· a return activated sludge system is not required since both aeration and settling occur in the same
    tank, resulting in less capital and operating costs for return sludge pumping;
· the SBR process has the ability to equalize flows and loads and it can tolerate high flows and/or
    substantial shock loads without a degradation in effluent quality;
· increased settling area and improved quiescent settling conditions relative to conventional plants; and,
· a smaller footprint is required since aeration and settling occur in one tank, resulting in reduced land
    costs and capital costs.

In addition to reducing the BOD5 concentrations, SBRs can significantly nitrify ammonium. The
reduction of nitrogen becomes more important with older landfills as nitrogen levels increase with age of
the leachate.

In addition to aerobic processes, leachate can be treated anaerobically using two-stage anaerobic reactors
or fixed-film anaerobic reactors. Anaerobic degradation naturally takes place within a sanitary landfill.
Further anaerobic treatment can be carried out once the leachate is pumped from the subsurface. In
anaerobic treatment systems, complex organic molecules are fermented by bacteria to volatile fatty acids
(primarily acetic, propionic, and butyric). Methanogenic bacteria then convert these acids to methane and
carbon dioxide. One of the main advantages of anaerobic systems over aerobic systems is that a lower
amount of solids is produced.

In a two-stage anaerobic reactor, the chambers are enclosed to prevent oxygen from entering the system
(maintaining anaerobic conditions) and to allow the capture of off gases. The first reactor is mixed to
ensure good contact between the microorganisms and the organic substrate. Mixing does not take place
in the second reactor to separation of the leachate into a supernatant and sludge. The supernatant is
recycled back to the first reactor for further treatment.

Fixed-film anaerobic filters involve slowly passing the leachate upwards through a media. The filter is
kept submerged in the leachate and a film of anaerobic bacteria builds up on the surface of the material.
The bacteria remains on the filter for a long period of time due to the low yield of the anaerobic process.

These technologies are applicable for landfill leachate remediation. Emphasis is placed on the fact that
sites potentially suited for stormwater management facilities may in fact be old dumps or landfills.



                                                                                     City of Toronto   1 - 83
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Therefore, application of these types of technologies may be required in order to make effective use of
those sites.

Application Requirements: In order to maintain the biological action in the aerobic phase, large
quantities of oxygen must be supplied. Leachates from older landfills (which is the case for the study
area) tend to contain a greater proportion of refractory material in the organic fraction. Therefore, older
leachates will be less amenable to biological treatment.

In order to maintain the biological action in an anaerobic treatment system, the unit must be fully
enclosed to ensure that no oxygen enters the system (i.e. maintain anaerobic conditions). Acidic pH must
be avoided as this condition inhibits the microorganisms, and in particular the methanogenic bacteria.
Optimal performance is achieved at temperatures ranging between 20oC and 35oC.

Proven Effectiveness/Experience Elsewhere: Considerable bench-scale research has been conducted to
determine whether concentrated leachates can be treated in biological treatment systems. Results from
the literature indicate that BOD5 removals were excellent. Effluent COD values have been reported to be
high but may be primarily humic, fulvic, and tannic acids and lignins, which are biologically inert.

The use of two stage anaerobic reactors has proven to be effective; however, fixed-film anaerobic units
are more commonly used now. The effectiveness of anaerobic treatment systems diminishes as the easily
degraded organics are removed, the remaining amount becomes more difficult to degrade.

Cost Considerations: Design and construction costs of an aerated lagoon will depend on the strength of
the leachate. Typical design considerations include organic loading (food:microorganism <0.3), solids
retention time (>10 days at 20oC, >20 days at 10oC), sludge production rates (up to 1 kg/kg of BOD
removed), oxygen supply (large need for young leachate), and PO4-P supplement. Large quantities of
biomass sludge may be produced from biological treatment of landfill leachate, which would result in
significant disposal costs. Aeration of these lagoons requires substantial energy, and therefore, increased
costs. Costs for discharging to the sanitary sewer would also be incurred.

Design and construction costs of a SBR system will depend on the strength of the leachate. Typical
design considerations include organic loading (food:microorganism <0.3), solids retention time (>10 days
at 20oC, >20 days at 10oC), sludge production rates (up to 1 kg/kg of BOD removed), oxygen supply
(large need for young leachate), and PO4-P supplement. Large quantities of biomass sludge may be
produced from biological treatment of landfill leachate, which would result in significant disposal costs.
Costs for discharging to the sanitary sewer would also be incurred.

Anaerobic treatment systems do not require mixing. Therefore, less energy costs are incurred. Anaerobic
treatment systems produce a significantly lower amount of sludge (i.e. organics are converted to gas
instead of biomass), which reduces the solids disposal costs. Costs for discharging to the sanitary sewer
would also be incurred.




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Objectives Addressed:

                                   Technical Objectives                                      Measure
                                                                                             Addresses
1.      Achieve healthy aquatic communities                                                     X
2.      Reduce fish consumption advisories                                                      X
3.      Reduce erosion impacts
4.      Re-establish natural hydrologic process
5.      Re-establish natural features
6.      Virtual elimination of toxic contaminants using pollution prevention at source
7.      Achieve water and sediment objectives in watercourses and waterfront                          X
8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
9.      Improve body contact recreation in rivers and reduce beach closures                           X
10.     Eliminate aesthetic nuisances                                                                 X
11.     Reduce basement flooding
12.     Reduce sanitary sewer inflow and infiltration
13.     Protect life and property from flooding

Opportunities Considerations:
· Treatment of landfill leachate using ex-situ biological treatment technologies would first require the
   installation of a leachate collection system, such as pumping wells or interceptor trenches. In
   addition, physical/chemical treatment process would likely be conducted sequentially with the
   biological treatment to remove other constituents of landfill leachate (e.g. metals). Treated leachate
   would be discharged to the sanitary sewers. Application of these technologies would depend on land
   availability, as industrial facilities or other private buildings (as opposed to City properties) may
   occupy many of the closed landfills within the study area.
· In some instances, an anaerobic treatment system followed by aerobic treatment is the most effective
   approach in reducing BOD5 levels.
· Large quantities of oxygen must be supplied to maintain aerobic conditions.
· Anaerobic units must be fully enclosed to maintain aerobic biological activity and optimal
   temperatures range between 20oC and 35oC.
· Acidic pH levels must be avoided in anaerobic systems.
· Older leachates will be less amenable to biological treatment as it tends to contain a greater
   proportion of refractory material in organic fraction.

References:

·     McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
      Hall Canada, 1995
·     U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




                                                                                    City of Toronto       1 - 85
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Example of Typical Rotating Biological Contactor Unit




Example of Typical Trickling Filter Unit




1 - 86   City of Toronto
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Ex-Situ Physical/Chemical Leachate
Treatment Technologies
Remediation Type: Source Controls

Primary Mechanism: Chemical conversion or physical separation

Related WWMPs: N/A

Description: Leachate generated from municipal landfills consist of numerous constituents, including
organic strength (BOD, COD), ammonia, heavy metals (i.e. iron, zinc, lead, and copper), phosphorus, pH,
and conservative ions (i.e. chloride, sodium, sulphate). As such, various remedial alternatives will be
required to treat landfill leachate.

As the landfill leachate stabilizes over time, there is a decrease in the proportion of organic compounds
that are readily biodegradable. Therefore, physical/chemical treatment alternatives replace or are used in
conjunction with aerobic and/or anaerobic biological treatment systems. In addition to organics, these
processes treat other constituents of landfill leachate. Physical/chemical treatment processes include
carbon adsorption, chemical precipitation, ultrafiltration, and reverse osmosis.

Activated carbon units are generally configured in a column; however, dispersed carbon treatment
systems also exist. The leachate is pumped through a series of canisters or columns containing activated
carbon to which dissolved organic contaminants adsorb. The liquid can be passed through the columns
by downflow or upflow. In the latter case, case carbon can be packed or suspended. Once the carbon is
exhausted, it can be regenerated on-site, removed and regenerated off-site, or disposed of off-site.

In biological treatment of landfill leachate, heavy metals are removed in the form of either metal sulfides
(anaerobic treatment) or as metal hydroxides (aerobic treatment). If the metal content is too high or there
was no biological treatment, metals can be removed by chemical precipitation with lime or caustic.
Metals precipitation involves the conversion of soluble heavy metal salts that will precipitate. The
precipitate is then removed from the liquid by physical processes, such as settling and/or filtration.
Chemical coagulants are often added to promote the bonding and settling of very fine particles in the
precipitate.

Filtration is the process where suspended particles in liquid are forced through a porous medium. As the
liquid passes through the medium, the suspended particles are trapped on the surface of the medium
and/or within the body of the medium. Ultrafiltration occurs when a liquid is forced through a semi-
permeable membrane, whereby only particles that are smaller than the openings of the membrane are
allowed to pass through.

Reverse osmosis (RO) is a physical separation process whereby contaminants are removed from a liquid
by using pressure. Osmosis is a natural phenomenon wherein a liquid flows through a semi-permeable
membrane from a relatively dilute solution towards a more concentrated solution. This flow produces a
pressure called osmotic pressure. If pressure greater than the osmotic pressure is applied to the more
concentrated solution, water flows through the membrane from the more concentrated side to the dilute
solution. This process is called reverse osmosis.




                                                                                     City of Toronto   1 - 87
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These technologies are applicable for landfill leachate remediation. Emphasis is placed on the fact that
sites potentially suited for stormwater management facilities may in fact be old dumps or landfills.
Therefore, application of these types of technologies may be required in order to make effective use of
those sites.

Application Requirements: The target contaminant groups for activated carbon adsorption include
hydrocarbons and SVOCs. As such, it is applicable for treating contaminated groundwater from leaking
petroleum USTs, industrial sites, or organics in landfill leachate. The removal efficiency in halogenated
VOCs and pesticides is limited. It is particularly effective in reducing COD levels in landfill leachate.
Low concentrations of organics in leachate or groundwater (less than 10 mg/L) can be effectively
removed at almost any flow rate. For removal of higher concentrations, a low flow rate must be used
(typically 2 to 4 litres per minute).

The presence of multiple contaminants can reduce the effectiveness of activated carbon. Filtering may be
required to reduce high concentrations of suspended solids (>50 mg/L) or oil and grease (>10 mg/L), to
maintain optimal performance.

The target contaminant group for chemical precipitation is dissolved ionic species in solution (i.e. heavy
metals). As such, it is applicable for treating heavy metals in landfill leachate or metals-contaminated
groundwater associated with industrial sites.

To determine the applicability of chemical precipitation, bench-scale testing should be conducted to
determine operating parameters and characteristics (e.g. reagent type and dosage, optimum pH, retention
time, flow rate, temperature, etc.)

The target contaminant groups for ex-situ separation techniques, such as ultrafiltration, include VOCs,
SVOCs, pesticides, and suspended particles. These separation techniques are typically used as either as a
pre-treatment or post-treatment process, and can be applied to contaminated groundwater or landfill
leachate.

RO separation processes may be appropriate in specific leachate treatment applications. With the
exception of acetic-phase leachate, RO can produce good quality effluent. The cellulose acetate
membranes are highly pervious to acetic acid. Biological pre-treatment would be required in leachate
with acetic acid.

Proven Effectiveness/Experience Elsewhere: The concepts, theory, and engineering aspects of activated
carbon are well developed, and it is a proven technology. The use of granular activated carbon or
powdered activated carbon has proven to be very effective in for treating poorly biodegradable organics,
solvents, pesticides, and humic acids. Therefore, carbon adsorption can effectively reduce COD in “old”
leachates or remove colour and refractory organics contributing to residual COD. It is possible to reduce
COD levels to a range of 0 to 100 mg/L.

Chemical precipitation has long been used for treating metals-contaminated industrial wastewater. As a
result of its proven effectiveness in this type of application, chemical precipitation has been used in
treating landfill leachate and is also becoming the most widely selected method to remediate metals
contaminated groundwater in pump and treat operations.

Ultrafiltration is an effective method for removing high molecular weight material from landfill leachate.
The effectiveness of ultrafiltration can be improved by pretreating the leachate with a biological process
to remove particulate matter, which would otherwise foul the filter.




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                                                                                    SOURCE CONTROLS


RO can remove up to 98% of dissolved minerals and virtually 100% of colloidal and suspended matter.
The effectiveness of RO units increases with increasing pressure and temperature.

Cost Considerations: Activated carbon costs depend on wastestream flow rates, type of contaminant,
concentration of contaminant, mass loading, required effluent concentration, and site timing requirements.
Costs are lower at higher flow rates. The primary factors affecting operating costs are labour and
chemicals. Sludge disposal costs would also be incurred, and could be significant if the sludge is
hazardous as a result of concentrated metals.

Objectives Addressed:

                                   Technical Objectives                                        Measure
                                                                                               Addresses
 1.    Achieve healthy aquatic communities                                                        X
 2.    Reduce fish consumption advisories                                                         X
 3.    Reduce erosion impacts
 4.    Re-establish natural hydrologic process
 5.    Re-establish natural features
 6.    Virtual elimination of toxic contaminants using pollution prevention at source
 7.    Achieve water and sediment objectives in watercourses and waterfront                           X
 8.    Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9.    Improve body contact recreation in rivers and reduce beach closures                            X
 10.   Eliminate aesthetic nuisances                                                                  X
 11.   Reduce basement flooding
 12.   Reduce sanitary sewer inflow and infiltration
 13.   Protect life and property from flooding

Opportunities Considerations:
· The use of carbon adsorption as the primary treatment method may not be feasible, given the high
   costs that can be incurred if contaminant concentrations are high (e.g. regeneration or disposal of
   spent carbon). However, if used as a secondary treatment method with another remediation
   technology, activated carbon can effectively polish pre-treated water, such that it can meet regulatory
   requirements for sanitary sewer discharge.
· Activated carbon can be used for treating landfill leachate (possibly on its own or in conjunction with
   a biological treatment process). It can also be used for treatment of contaminated groundwater at
   leaking UST sites or industrial properties with SVOC impacts. Depending on the concentrations at
   these sites, it may be used as a stand-alone process or as secondary treatment prior to discharge to a
   sanitary sewer.
· Chemical precipitation has been widely used for treatment of metals-laden industrial wastewater. As
   such, it is a possible option for treating heavy metals in landfill leachate and may be used in
   conjunction with a biological treatment process. This technology would also be applicable for
   treating metals contaminated groundwater from industrial sites.
· Ultrafiltration is not typically used as a stand-alone remediation technique for contaminated
   groundwater or leachate. It may be used as a pre-treatment or post-treatment process with another
   technology.
· RO is a possible remedial option in treating certain landfill leachate constituents such as sodium,
   chloride, and some metals. The application of RO would likely be in combination with another
   treatment technology for remediation of landfill leachate (e.g. biological treatment).
· Carbon adsorption is targeted to treat hydrocarbons and SVOCs in contaminated groundwater.
   Removal efficiency of VOCs and pesticides is limited.


                                                                                    City of Toronto   1 - 89
SOURCE CONTROLS


·   Carbon adsorption is particularly effective in reducing COD levels in landfill leachate.
·   Chemical precipitation is targeted at treating dissolved ionic species in solution (i.e. heavy metals).
·   Ultrafiltration is applicable for treating VOCs, SVOCs, pesticides, and suspended solids. Typically
    not used as a stand-alone treatment process.
·   Reverse osmosis is not effective in acetic-phase leachate.

References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




1 - 90   City of Toronto
                                                   SOURCE CONTROLS


Example of Typical Carbon Adsorption Unit




Example of Typical Chemical Precipitation System




                                                   City of Toronto   1 - 91
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Example of Typical Filtration System




Example of Typical Reverse Osmosis System




1 - 92   City of Toronto
                                                                                   SOURCE CONTROLS




Co-Metabolic, Enhanced
Biodegradation, Natural Attenuation
(Groundwater Remediation for Leaking USTs)
Remediation Type: Source Controls

Primary Mechanism: In-Situ Biological Treatment

Related WWMPs: N/A

Description: USTs are most commonly used to store petroleum products, such as gasoline, diesel, and
heating oil. Fuel products contain hundreds of hydrocarbon compounds. Benzene, toluene, ethylbenzene,
and xylene (BTEX) and total petroleum hydrocarbons (TPH) are the most common parameters used in the
assessment and remediation of leaking petroleum USTs.

In-situ biological treatment methods include co-metabolic processes, enhanced biodegradation, and
natural attenuation. In-situ bioremediation techniques involve stimulating microorganisms in the
subsurface to grow and use the contaminants as a food and energy source. The rate at which the
microorganisms degrade the contaminants depends on the type of contaminant and concentration,
availability of the contaminant, oxygen supply, nutrient supply, moisture, pH . The main advantage of in-
situ biological treatment is that contaminated groundwater can be treated without being brought to
surface, thereby reducing the costs.

Co-metabolism consists of secondary substrate transformation in which enzymes produced for primary
substrate oxidation are capable of degrading the secondary substrate, even though the secondary
substrates do not provide sufficient energy to sustain the microbial population. This process can be
achieved by injecting water containing dissolved primary substrate (e.g. methane, toluene) and oxygen
into the groundwater to support the co-metabolic breakdown of targeted organic compounds.

Enhanced bioremediation is a process that accelerates the natural biodegradation process by providing
nutrients, electron acceptors (oxygen for aerobic conditions and nitrate for anoxic conditions), and
competent degrading microorganisms. Oxygen is provided by air sparging below the water table or
circulating hydrogen peroxide throughout the contaminated groundwater zone.

Natural attenuation is the reduction of contaminant concentrations by natural subsurface processes during
the transport of contaminated groundwater (i.e. hydrocarbons in leaking USTs) through the soil
environment. These natural subsurface processes include dilution, volatilization, biodegradation,
adsorption, and chemical reactions with subsurface materials. Natural attenuation is not necessarily
considered a “technology”. Although commonly perceived as a “no action” option, natural attenuation is
not considered the same, as it involves contaminant modelling and long-term groundwater monitoring.

These technologies are applicable for groundwater remediation of leaking USTs.

Application Requirements: Co-metabolism has shown limited applications to some petroleum
compounds (i.e. primary target contaminants are chlorinated solvents). The use of co-metabolic treatment
processes is more applicable in homogenous subsurface conditions, as heterogeneous conditions create



                                                                                   City of Toronto   1 - 93
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difficulties in circulating the methane solution. Higher permeability zones will remediated much faster
because groundwater flow rates are much greater. High copper concentrations affect methanotrophic
cometabolism.

Target contaminants for enhanced biodegradation include fuels and other organic compounds. Nitrate
enhancement has primarily been used to remediate BTEX contaminated groundwater. Use of this
technology in heterogeneous subsurface conditions may not be applicable due to difficulties in delivering
nitrate or hydrogen peroxide throughout the entire contaminant zone.

Natural attenuation may be a potential option to remediate leaking UST sites. The use of this alternative
will depend on the predicted degradation rates and long-term concentrations at the receptor point.

Proven Effectiveness/Experience Elsewhere: Enhanced biodegradation is more affective at remediating
fuel contaminants than co-metabolic processes and natural attenuation.

In-situ application of co-metabolism has not yet been demonstrated at a practical scale. As with other in-
situ biodegradation processes, the success of enhanced biodegradation is dependant on soil properties and
biodegradability of the contaminant. At a DOE test site at Savannah River, concentrations of TCE and
PCE decreased from concentrations of 1,000 ppb to less than 2 ppb, when methanotroph densities
increased five orders of magnitude.

In the US, natural attenuation is considered in the Superfund program and hazardous waste sites are
evaluated on a case-by-case basis.

Cost Considerations: In-situ co-metabolic has not yet been used at a full-scale level. However, pilot-
scale demonstration carried out by the US Department of Energy incurred a capital cost of $150,000 US.
Operation and maintenance costs can be significant because of the continuous requirement of methane
solution.

Factors affecting enhanced biodegradation include the type and depth of the contaminant, use of
bioaugmentation, hydrogen peroxide, or nitrate addition.

Costs associated with natural attenuation consist primarily of modelling and long-term monitoring.
Monitoring generally comprises the most significant costs and includes both site characterization and
performance monitoring.




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Objectives Addressed:

                                   Technical Objectives                                         Measure
                                                                                                Addresses
 1.    Achieve healthy aquatic communities                                                         X
 2.    Reduce fish consumption advisories                                                          X
 3.    Reduce erosion impacts
 4.    Re-establish natural hydrologic process
 5.    Re-establish natural features
 6.    Virtual elimination of toxic contaminants using pollution prevention at source
 7.    Achieve water and sediment objectives in watercourses and waterfront                            X
 8.    Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9.    Improve body contact recreation in rivers and reduce beach closures
 10.   Eliminate aesthetic nuisances                                                                   X
 11.   Reduce basement flooding
 12.   Reduce sanitary sewer inflow and infiltration
 13.   Protect life and property from flooding

Opportunities Considerations:
· Considering that contaminated groundwater can be treated without being brought to surface (lower
   costs), the use of in-situ bioremediation should be assessed. However, the application of these types
   of technologies will highly depend on the site-specific subsurface conditions (e.g. permeability,
   homogeneity, etc.).
· There are a number of advantages to natural attenuation, and its use for remediation of leaking UST
   sites should at least be assessed. These include less generation of remediation wastes, less intrusive,
   may be applied to all or part of a site, and overall costs will likely be lower than active remediation.
· Co-metabolism is targeted at treating chlorinated solvents, and to a limited extent, petroleum
   compounds in contaminated groundwater.
· Heterogeneous subsurface conditions create difficulties in circulating the methane solution in co-
   metabolism treatment.
· High copper concentrations limits methanotrophic cometabolism.
· Enhanced biodegradation is applicable for treatment of fuels and other organic compounds.
· Heterogeneous subsurface conditions create difficulties in delivering nitrate or hydrogen peroxide
   throughout the contaminant zone.
· Use of natural attenuation to remediate petroleum or other organic contaminated groundwater will
   depend on the findings of the modelling.

References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




                                                                                     City of Toronto   1 - 95
SOURCE CONTROLS


Example of Typical Co-Metabolic Treatment System




Example of Typical Enhanced Biodegradation System




1 - 96   City of Toronto
                                                                                      SOURCE CONTROLS




Air Sparging, Bioslurping, Dual Phase
Extraction, Fluid/Vapour Extraction,
Steam Flushing/Stripping, In-Well Air
Stripping
(Groundwater Remediation for Leaking USTs)
Remediation Type: Source Controls

Primary Mechanism: In-Situ Physical/Chemical Treatment

Related WWMPs: N/A

Description: USTs are most commonly used to store petroleum products, such as gasoline, diesel, and
heating oil. Fuel products contain hundreds of hydrocarbon compounds. Benzene, toluene, ethylbenzene,
and xylene (BTEX) and total petroleum hydrocarbons (TPH) are the most common parameters used in the
assessment and remediation of leaking petroleum USTs.

In-situ physical/chemical treatment technologies used to remediate petroleum-contaminated groundwater
include air sparging, bioslurping, dual phase extraction, fluid/vapour extraction, steam flushing/stripping,
and in-well air stripping. Physical/chemical treatment processes utilize the physical properties of the
contaminants or the contaminated medium to chemically convert or separate the contamination. Although
categorized as an in-situ technique, some of these technologies involve extraction of groundwater, free-
phase product, and hydrocarbon vapours. Similar to in-situ biological treatment techniques, in-situ
physical/chemical treatment has the main advantage of remediating the groundwater without being
brought to surface, which results in significant cost savings. In-situ chemical/physical treatment is
typically cost effective and requires less time to complete than in-situ biological treatment. However, in
both cases, there is less certainty than in the case of ex-situ techniques about the uniformity of treatment
because of the variability in aquifer characteristics.

Air sparging involves injecting air into a contaminated aquifer, thereby creating an underground stripper
that removes contaminants by volatilization. The contaminants “bubble” up into the unsaturated zone
where a soil vapour extraction system removes the generated vapour phase contamination.

Bioslurping is a combination of bioventing and vacuum-enhanced free product recovery used to
simultaneously recover free-product and bioremediate vadose zone soils. One of the main advantages of
bioslurping is that it can improve free-product recovery without pumping large quantities of groundwater.
Vacuum-enhanced pumping allows LNAPL to be lifted off the water table and released from the capillary
fringe, thereby reducing the watertable drawdown (i.e. minimizing smearing). Bioventing of vadose zone
contaminated soils is accomplished by drawing air into the soil matrix due to withdrawing soil gas from
the recovery well.

Dual-phase extraction (DPE), also known as multi-phase extraction (MPE), vacuum-enhanced extraction,
or sometimes bioslurping, is a technique that uses a high vacuum system to remove a combination of




                                                                                      City of Toronto   1 - 97
SOURCE CONTROLS


contaminated groundwater, separate-phase petroleum product, and hydrocarbon vapour. The extracted
liquids and vapour are treated and disposed of off-site or where permissible, re-injected to the subsurface.

Fluid/vapour extraction is a high vacuum system, which simultaneously removes liquid and gas from low
permeability or heterogeneous soil formations. The extraction well is screened above and below the
watertable, and the vacuum lowers the watertable, thereby exposing more of the formation. The high
vacuum causes groundwater and soil vapours to flow towards the extraction well at a faster rate. Because
of the turbulence created during extraction, most of the contaminants in the water are stripped away, and
little additional treatment is required.

In steam flushing/stripping systems, steam is forced into an aquifer through injection wells to vapourize
volatile and semi-volatile contaminants. Vapourized contaminants rise to the vadose zone where they are
removed by vacuum extraction and then treated.

In-well air stripping is a process where air is injected into a double-screened well, lifting the water in the
well and forcing it out the upper screen. At the same time, additional water is drawn in the lower screen.
Once in the well, some of the VOCs in the contaminated groundwater are transferred from the dissolved
phase to the vapour phase by bubbles. The vapours are extracted and treated before discharge. The water
is not brought to surface. Rather, it is discharged into the vadose zone and recycling process continues.

These technologies are applicable for groundwater remediation of leaking USTs.

Application Requirements: The target contaminant groups for air sparging include fuels and VOCs.
The depth of the contaminants and site-specific geology are significant factors when assessing the
applicability of this technology. Soil heterogeneity may cause some zones to be untreated.

Bioslurping is designed to remediate soils contaminated by petroleum hydrocarbons. It is applicable at
sites with a deep watertable (i.e. > 9 metres). Bioslurping is less applicable and effective in low
permeability soils. The off-gases typically require treatment before discharge. Mixing of the fuel, water,
and vapours occur as these phases are extracted in one stream. The mixture may require a special
oil/water separator or treatment before the process water can be discharged.

The target contaminant groups for DPE systems are fuels (e.g. LNAPL) and VOCs. The site-specific
geology and contaminant characteristics/distribution will influence the applicability of DPE. Although
more effective than SVE systems for heterogeneous clays and fine sands, DPE is not recommended for
lower permeability formations due to the potential to leave isolated lenses of LNAPL.

Fluid/vapour extraction is targeted at remediating sites contaminated by fuel or VOCs. It is more
effective than SVE for heterogeneous clays and fine sands, and is typically used in the vadose zone with a
soil hydraulic conductivity of 10-8 to 10-3 cm/s).

The target contaminant groups for steam flushing/stripping are fuels and SVOCs.              The process is
applicable to shallow and deep contaminated areas.

In-well air stripping is applicable to applicable for treatment of groundwater contaminated by fuels,
halogenated VOCs, and SVOCs. In general, in-well air strippers are more applicable and effective at sites
containing high concentrations of dissolved contaminants with high Henry’s law constants. This type of
system is generally not applicable at sites with a shallow aquifer.




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Proven Effectiveness/Experience Elsewhere: Air sparging has been undertaken at many sites, although
only a few sites are well documented. This technology has shown it is sensitive to minute permeability
changes, which results in localized stripping.

The U.S. Navy and Air Force have demonstrated successful bioslurping projects at a few sites. In Fallon,
Nevada, the Navy was able to remove 6,500 gallons of jet fuel leaked into the subsurface. On the island
of Diego Garcia, the Air Force recovered jet fuel at a rate of 1,000 gallons per month, which had leaked
into the ground during the Persian Gulf War.

At the McClellan Air Force Base in the U.S., the pilot-scale test indicates that fluid/vapour extraction will
be effective in low permeability silts. Results show that the groundwater flow rate and radius of influence
increased twice that of conventional pump-and-treat systems.

Steam flushing/stripping is a pilot-scale technology. Contained Recovery of Oily Waste (CROW), which
is a steam-based technique, was tested both at the laboratory and pilot-scale levels under the USEPA
SITE Emerging Technology Program.

A variation of the in-well air stripping system, called Unterdruck-Verdampfer Brunner (UVB), has been
used at many sites in Germany and has recently been tested in the U.S. Stanford University has
developed a similar system, called NoVOCs, which is currently being evaluated as part of the U.S.
Department of Energy’s Integrated Technology Demonstration Program.

Cost Considerations: The cost to implement air sparging is highly variable and is dependant on site-
specific conditions (e.g. depth to contaminants, plume size, etc.).

As with other in-situ technologies, implementation costs are highly variable due to site-specific
conditions. Key factors that affect the cost for DPE systems include waste disposal, potential sale of
recovered product, on-site equipment rental (e.g. pumps, tanks), installation of permanent equipment (e.g.
recovery wells), and engineering.

Key factors that affect the cost of fluid/vapour extraction systems include site geology, contaminant
properties, waste disposal, potential for sale of recovered product, on-site equipment rental, installation of
permanent equipment, and engineering.

The most significant factor affecting the cost of in-situ steam flushing/stripping systems is the number of
wells required per unit area, which is related to the permeability and site geology, and depth of
contamination.




                                                                                       City of Toronto   1 - 99
SOURCE CONTROLS


Objectives Addressed:

                                   Technical Objectives                                      Measure
                                                                                             Addresses
 1.    Achieve healthy aquatic communities                                                      X
 2.    Reduce fish consumption advisories                                                       X
 3.    Reduce erosion impacts
 4.    Re-establish natural hydrologic process
 5.    Re-establish natural features
 6.    Virtual elimination of toxic contaminants using pollution prevention at source
 7.    Achieve water and sediment objectives in watercourses and waterfront                       X
 8.    Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9.    Improve body contact recreation in rivers and reduce beach closures
 10.   Eliminate aesthetic nuisances                                                              X
 11.   Reduce basement flooding
 12.   Reduce sanitary sewer inflow and infiltration
 13.   Protect life and property from flooding

Opportunities Considerations:
· In-situ chemical/physical treatment techniques generally offer the advantage of treating the
   contaminant without being brought to surface, although some techniques require extraction of
   multiple phases, which typically require some form of pre-treatment before being discharged. The
   use of these technologies will need to be assessed on a case-by-case basis as they are highly
   dependant on the site-specific subsurface conditions (e.g. permeability, homogeneity, etc.).
· Air sparging is targeted for remediation groundwater contaminated by fuels and VOCs.
   Heterogeneities in the soil may cause some zones to be untreated.
· Bioslurping is targeted for remediation of petroleum contaminated soil in the vadose zone and
   includes free-product recovery. It is applicable at sites with a deep watertable, and less effective in
   low permeability soils.
· DPE is targeted for removal of fuels and VOC contamination in multiple phases (i.e. groundwater,
   free-product, and vapour). Not recommended for low permeability soils.
· Fluid/vapour extraction is targeted for removal of groundwater and soil vapour contaminated by fuels
   and VOCs. Effective in low permeability soils.
· Steam flushing/stripping is targeted for remediation of fuels or VOC contaminated groundwater.
   Applicable in shallow and deep contaminated areas.
· In-well air stripping is applicable for treatment of groundwater contaminated by fuels, halogenated
   VOCs, and SVOCs. More effective for contaminants with high Henry’s law constants.

References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




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                                                      SOURCE CONTROLS




Example of Typical Air Sparging System




Example of Typical Bioslurping System




Example of Typical Dual Phase Extraction Schematic




                                                     City of Toronto   1 - 101
SOURCE CONTROLS


Example of Typical Free Product Dual Recovery Pump System




Example of Typical Fluid Vapour Extraction Schematic




Example of Typical Steam Flushing/Stripping System




1 - 102   City of Toronto
                                                   SOURCE CONTROLS


Example of Typical In-Well Air Stripping System




                                                  City of Toronto   1 - 103
SOURCE CONTROLS




Natural Attenuation
(Landfill Leachate Remediation / Groundwater Remediation for Leaking
USTs)
Remediation Type: Source Controls

Primary Mechanism: Natural subsurface processes (Dilution, Volatilization, Biodegradation,
Adsorption, Chemical Reaction)

Related WWMPs: N/A

Description: Natural attenuation is the reduction of contaminant concentrations by natural subsurface
processes during the transport of leachate or contaminated groundwater through the soil environment.
These natural subsurface processes include dilution, volatilization, biodegradation, adsorption, and
chemical reactions with subsurface materials. Natural attenuation is not a “technology” per se. Although
commonly perceived as a “no action” option, natural attenuation is not considered the same, as it involves
contaminant modelling and long-term groundwater monitoring. Modelling consists of evaluating the
contaminant degradation rates and pathways, and predicting concentrations at downgradient receptor
points. Long-term monitoring is required to verify that natural degradation is proceeding at the predicted
rates, which will meet the cleanup objectives.

This technology is applicable for groundwater remediation for leaking USTs and landfill leachate
remediation.

Application Requirements: Natural attenuation may be a potential option to remediate landfill leachate,
leaking USTs, and contaminated groundwater from industrial sites (e.g. brownfields). The use of this
alternative will depend on the predicted degradation rates and long-term concentrations at the receptor
point.

Target compounds for this remedial alternative include halogenated VOCs, SVOCs, and fuel
hydrocarbons. Some pesticides may be considered for natural attenuation, but are generally less effective
than the aforementioned contaminant groups. Selected metals may also be appropriate for natural
attenuation if the processes cause a change in valence states, which results in immobilization (e.g.
chromium).

Other factors that need to be assessed include the mobility and toxicity of the degradation products (e.g.
TCE degrades to vinyl chloride which is more toxic), presence of free product, whether imminent risks
are present, and long-term monitoring costs.

Proven Effectiveness/Experience Elsewhere: Prior to the early 1970s, landfills greater than 20 years old
servicing major municipalities were managed by natural attenuation. Since that time, landfills have
focussed on minimizing the impacts to the environment by implementing engineering controls, such as
site location evaluation (for new landfills), surface water management, low permeability landfill bases
and caps, and leachate collection and treatment.

In the US, natural attenuation is considered in the Superfund program and hazardous waste sites are
evaluated on a case-by-case basis.




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Cost Considerations: Costs associated with natural attenuation consist primarily of modelling and long-
term monitoring. Monitoring generally comprises the most significant costs and includes both site
characterization and performance monitoring.

Objectives Addressed:

                                   Technical Objectives                                         Measure
                                                                                                Addresses
 1.    Achieve healthy aquatic communities                                                         X
 2.    Reduce fish consumption advisories                                                          X
 3.    Reduce erosion impacts
 4.    Re-establish natural hydrologic process
 5.    Re-establish natural features
 6.    Virtual elimination of toxic contaminants using pollution prevention at source                 X
 7.    Achieve water and sediment objectives in watercourses and waterfront                           X
 8.    Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9.    Improve body contact recreation in rivers and reduce beach closures
 10.   Eliminate aesthetic nuisances
 11.   Reduce basement flooding
 12.   Reduce sanitary sewer inflow and infiltration
 13.   Protect life and property from flooding

Opportunities Considerations:
· As mentioned above, engineered controls have been implemented at landfills since the early-1970s.
   Nonetheless, natural attenuation is still currently used, particularly in smaller municipalities. Natural
   attenuation can also play an important role for engineered landfills, as some discharge may still occur
   even if the site was properly designed.
· There are a number of advantages to natural attenuation, and its use for remediation of landfill
   leachate, leaking USTs, and contaminated soil at industrial sites should at least be assessed. These
   include less generation of remediation wastes, less intrusive, may be applied to all or part of a site,
   and overall costs will likely be lower than active remediation.
· Use of natural attenuation for soil cleanup, groundwater remediation of leaking USTs, landfill
   leachate remediation will depend on the findings of the modelling.

References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




                                                                                    City of Toronto   1 - 105
SOURCE CONTROLS




Waterloo Barrier
(Landfill Leachate Remediation / Groundwater Remediation for
Leaking USTs)
Remediation Type: Source Controls

Primary Mechanism: Groundwater
containment using impermeable
vertical cut-off wall

Related WWMPs: Slurry wall

Description:       The      Waterloo
Barrierâ      is    a    groundwater
containment technology consisting of                         Waterloo Barrier schematic
sealable steel sheet piling. Researchers at the Waterloo Centre for Groundwater Research (WCGR),
University of Waterloo developed and patented this technology. A foot-plate at the base of the
interlocking joints of the sheet piles (i.e. sealable cavity) displaces soil laterally during the pile driving
process to prevent the accumulation of compacted soil within the cavity. After the sheet piles are driven
into the ground, the sealable cavities are flushed clean with pressurized water and inspected to ensure that
the full length of the cavity can be sealed. The cavity is then sealed with one of several types of
compounds, depending on site conditions. These include clay-based grouts such as bentonite and
attapulgite, cement-based grouts modified with expanding agents, epoxy polymers, urethane polymers,
and inflatable mechanical packers. Testing conducted by the WCGR indicates that the system typically
achieves a hydraulic conductivity of 10-8 to 10-10 cm/s.

The Waterloo Barrierâ can be used to prevent off-site migration of contaminated groundwater or gases,
such as landfill leachate and leaks from USTs. It can also be used to isolate a contaminated site while
other remediation technologies are being implemented. Further, Waterloo Barrierâ can be installed in an
alignment which would funnel the contaminated groundwater to an in-situ treatment media.

This technology is applicable for groundwater remediation for leaking USTs and landfill leachate
remediation.

Application Requirements: The Waterloo Barrierâ is applicable in various geological conditions (i.e.
sands, clays) and in a wide variety of applications. However, as with any typical sheet pile driving
projects, the use of the Barrier is not suitable in extremely dense or rocky soils. In addition, noise and
vibration generated from the pile driving equipment may limit is use in densely populated urban settings.

The selection of the cavity sealant is determined by the required service life of the installation, chemical
compatibility with groundwater contaminants, and whether or not the piling has to be removed from the
ground after remediation is completed.

Proven Effectiveness/Experience Elsewhere: This technology was developed in the late-1980s to early-
1990s. It has been used at a number of sites in Canada and over 25 across North America. Some
examples include:



1 - 106    City of Toronto
                                                                                           SOURCE CONTROLS




·        Dow Chemical Landfill Site, Sarnia, Ontario - The Barrier containment wall (approximately 16,000
         m2) was installed at the limits of this inactive waste disposal facility in the summer of 1997. Leachate
         from the landfill migrated laterally along fissures in weathered clay, and pooled on top of the
         unweathered consolidated clay. The Barrier was installed to prevent future migration of contaminants
         beyond the property boundary.
·        Former Shell Canada Site in Ports Industrial Area, Toronto, Ontario – This site was contaminated
         with hydrocarbons and heavy metals. A Waterloo Barrierâ containment wall (18,000 ft2) was
         installed at the downgradient property line to prevent the off-site migration of contaminated
         groundwater and to assist in dewatering during excavation activities.

Cost Considerations: Project costs are site-specific and depend on factors such as project size, location,
profile thickness of the sheet pile, type of sealant used, installation depth, and driving conditions.

Objectives Addressed:

                                        Technical Objectives                                        Measure
                                                                                                    Addresses
    1.      Achieve healthy aquatic communities                                                        X
    2.      Reduce fish consumption advisories                                                         X
    3.      Reduce erosion impacts
    4.      Re-establish natural hydrologic process
    5.      Re-establish natural features
    6.      Virtual elimination of toxic contaminants using pollution prevention at source
    7.      Achieve water and sediment objectives in watercourses and waterfront                           X
    8.      Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and
            spills
    9.      Improve body contact recreation in rivers and reduce beach closures                            X
    10.     Eliminate aesthetic nuisances                                                                  X
    11.     Reduce basement flooding
    12.     Reduce sanitary sewer inflow and infiltration
    13.     Protect life and property from flooding

Opportunities Considerations:
· Possible option for on-site containment of leachate and leaking USTs.
· May also be used in conjunction with a groundwater treatment system (e.g. pump and treat, in-situ
   bioremediation, etc.).
· Not suitable for extremely dense or rocky soils.

References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




                                                                                         City of Toronto   1 - 107
SOURCE CONTROLS




Slurry Wall
(Landfill Leachate Remediation / Groundwater Remediation for Leaking
USTs)
Remediation Type: Source Controls

Primary Mechanism: Groundwater containment using
impermeable vertical cut-off wall

Related WWMPs: Waterloo Barrier

Description: Slurry walls are subsurface barriers
consisting of vertically excavated trenches filled with a
bentonite and water mixture.        This slurry mixture
hydraulically shores the trench and forms a filter cake to
reduce groundwater flow. Slurry walls can be applied to
various situations such as containment of contaminated                      Slurry wall
groundwater (e.g. landfill leachate, leaking USTs, etc.),
divert contaminated groundwater from potable water supply wells, and to provide a barrier to be used in
conjunction with a groundwater treatment system. These types of containment structures are commonly
used where the contaminant plume is too large for treatment and where soluble and mobile contaminants
pose an imminent threat to potable groundwater sources.

Most slurry walls are constructed with a soil, bentonite, and water mixture. The bentonite slurry is used
primarily for wall stabilization during trench excavation. A soil-bentonite backfill is then placed into the
trench, thereby displacing the slurry to create the cut-off wall. If greater structural strength is needed or
the bentonite is compatible with the type of contaminants, other wall material can be used such as
cement/bentonite, pozzolan/bentonite, attapulgite, organically modified bentonite, or slurry/geomembrane
composite.

This technology is applicable for groundwater remediation for leaking USTs and landfill leachate
remediation.

Application Requirements: Slurry walls are typically placed at depths up to 30 metres and are generally
0.6 to 1.2 metres thick. Installation at depths greater than 30 metres is possible, but the costs increase by
a factor of three.

Soil-bentonite backfills are not able withstand attacks by strong acids, bases, salt solutions, and some
organic chemicals. There is also the potential for slurry walls to degrade or deteriorate over time.

Proven Effectiveness/Experience Elsewhere: Slurry walls are a full-scale technology that has been used
successfully for decades as long-term solutions for groundwater migration control. Although the
equipment and methodology are readily available and well known, the process of designing the proper
mix of wall materials to contain specific contaminants is less well developed. Experience contractors are
required as the timing of the excavation and backfilling process is critical.




1 - 108    City of Toronto
                                                                                   SOURCE CONTROLS


Cost Considerations: As noted above, costs generally increase by a factor of three in excavations greater
than 30 metres.

Factors with the most significant impact on the final cost of a soil-bentonite slurry include type of
contaminants, dimensions of wall, geological and hydrogeological conditions, distance from source of
materials and equipment, wall protection, and type of slurry.

Objectives Addressed:

                                  Technical Objectives                                       Measure
                                                                                             Addresses
 1.    Achieve healthy aquatic communities                                                      X
 2.    Reduce fish consumption advisories                                                       X
 3.    Reduce erosion impacts
 4.    Re-establish natural hydrologic process
 5.    Re-establish natural features
 6.    Virtual elimination of toxic contaminants using pollution prevention at source
 7.    Achieve water and sediment objectives in watercourses and waterfront                         X
 8.    Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and
       spills
 9.    Improve body contact recreation in rivers and reduce beach closures                          X
 10.   Eliminate aesthetic nuisances                                                                X
 11.   Reduce basement flooding
 12.   Reduce sanitary sewer inflow and infiltration
 13.   Protect life and property from flooding

Opportunities Considerations:
· Possible option for on-site containment of leachate and leaking USTs.
· May also be used in conjunction with a groundwater treatment system (e.g. pump and treat, in-situ
   bioremediation, etc.).
· Primarily suitable for depths up to 30 metres.
· Not suitable for use with strong acids, bases, and certain organic chemicals.

References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




                                                                                  City of Toronto   1 - 109
SOURCE CONTROLS




Pump and Disposal
(Landfill Leachate Remediation / Groundwater Remediation for Leaking
USTs)
Remediation Type: Source Controls

Primary Mechanism: Ex-situ Treatment
(Recovery by Interceptor Trenches or Pumping
Wells)

Related WWMPs: Pump and
On-Site Treatment Prior to Disposal

Description: Pumping of landfill leachate, or
groundwater contaminated by leaking USTs or
industrial sites is one of the more common
remediation technologies employed. It is used
either to remove dissolved contaminants or to
contain contaminated groundwater to prevent
                                                           Typical groundwater pumping station
migration. Interceptor trenches or pumping
wells can be installed, depending on site-
specific conditions, to recover the contaminated groundwater. Once brought to surface, the contaminated
liquid can either be remediated by an on-site ex-situ treatment system or directly disposed of off-site.
This technology description is for the latter approach. Ex-situ treatment processes are discussed in other
technology descriptions.

Landfill leachate pumped to surface may be discharged directly to the sanitary sewer for treatment at a
downstream wastewater treatment plant (WWTP), depending on the concentrations of the constituents in
the leachate/contaminated groundwater. In most cases, the WWTP will likely not accept the raw liquid
and will require some form of on-site pre-treatment prior to discharge to the sanitary sewer. Pumped
contaminated groundwater can also be transported off-site by vacuum trucks and disposed of at an MOE-
approved liquid treatment facility; however, this tends to be cost-prohibitive, depending on the volume of
impacted groundwater.

In addition to off-site disposal, extracted leachate can also be disposed of on-site. This is commonly
referred to as leachate re-circulation where the collected leachate is returned to the top of the landfill.
Leachate re-circulation will accelerate the stabilization of organic materials; however, this approach does
not eliminate the need for treatment since excess leachate will ultimately require treating.

This technology is applicable for groundwater remediation for leaking USTs and landfill leachate
remediation.

Application Requirements: The applicability of groundwater pumping will depend on the site
characteristics, such as hydraulic conductivity, chemical and biological properties of the contaminants,
and location and size of the plume. These and other site characteristics will need to be determined to
properly design an effective ground water pumping strategy.


1 - 110   City of Toronto
                                                                                       SOURCE CONTROLS




Direct discharge of pumped leachate to the sanitary sewer will depend on the quality of the raw liquid
with respect to the sewer use by-law and whether the WWTP can handle the loadings. Disposal at an off-
site treatment facility will depend on the volume of leachate or contaminated groundwater (i.e. transport
and disposal costs).

Proven Effectiveness/Experience Elsewhere: Pumping of leachate and contaminated groundwater for
treatment or containment purposes has been used for many years. However, direct discharge to a POTW
will likely not be approved without some form of pre-treatment.

Cost Considerations: The costs associated with pumping and disposal include capital expenditures for
construction of recovery wells (or trenches), annual monitoring and maintenance, and disposal (i.e. sewer
surcharge or off-site treatment facility). These costs will vary from site to site and will depend on specific
conditions, such as subsurface soil and groundwater conditions, the type of contaminants, size of plume,
and requirements of the WWTP.

Objectives Addressed:

                                    Technical Objectives                                          Measure
                                                                                                  Addresses
 1.    Achieve healthy aquatic communities                                                           X
 2.    Reduce fish consumption advisories                                                            X
 3.    Reduce erosion impacts
 4.    Re-establish natural hydrologic process
 5.    Re-establish natural features
 6.    Virtual elimination of toxic contaminants using pollution prevention at source
 7.    Achieve water and sediment objectives in watercourses and waterfront                             X
 8.    Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9.    Improve body contact recreation in rivers and reduce beach closures                              X
 10.   Eliminate aesthetic nuisances                                                                    X
 11.   Reduce basement flooding
 12.   Reduce sanitary sewer inflow and infiltration
 13.   Protect life and property from flooding

Opportunities Considerations:
· The installation of interceptor trenches or recovery wells to extract leachate or contaminated
   groundwater is a widely used technology and would likely be applicable at many sites within the
   study area. However, the option of direct discharge to a sanitary sewer without pre-treatment would
   likely not be approved by the WWTP.
· Leachate re-circulation can be used during the early stages of landfill development or utilized in older
   landfills (i.e. closed landfills within study area) to manage off-site disposal problems during peak
   production periods.
· Pumping wells are not suitable for dense soils (i.e. silts and clays), which will create a smaller zone of
   influence.
· Direct discharge to the sanitary sewers, without pre-treatment, may not be allowed if contaminant
   concentrations and other water characteristics exceed sewer use by-law criteria.
· WWTP would likely limit the daily discharge quantity.
· Off-site disposal at an MOE approved liquid disposal facility may be cost-prohibitive if groundwater
   volumes are high.



                                                                                      City of Toronto   1 - 111
SOURCE CONTROLS




References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




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Surface Capping
(Contaminated Site Cleanup)
Remediation Type: Source Controls

Primary Mechanism: Isolation of
contaminants

Related WWMPs: N/A

Description: Contaminated sites can
include both operating and abandoned
former       industrial       properties
(brownfields).        The types of
contaminants at industrial sites can
vary, depending on the types of
operations that were carried out (e.g.              Typical hazardous waste landfill cap design
metals, VOCs, SVOCs, pesticides).
The focus on contaminated industrial sites is the remediation of soil to address two potential pathways in
which the river can be impacted: 1) surface run-off carrying contaminated soil and 2) leaching of
contaminated soil into the groundwater which may ultimately migrate and discharge to the river.

Surface capping is one of the most common forms of remediating contaminated soil because it is
generally less expensive than other technologies. Also, it effectively manages the human and ecological
risks by eliminating the direct exposure to the contaminated soils (i.e. dermal, ingestion, and inhalation).
Capping also controls the emission of soil gases and prevents vertical infiltration of water, which could
leach contaminants off of the soil particles and down into the watertable.

The design and installation of a surface cap is site-specific and depends on the intended function of the
system. The materials used for capping include low and high permeability soils, and low-permeability
geosynthetic liners. The most critical components of a cap are the barrier layer and the drainage layer.
The low permeability materials divert water and prevent it from infiltrating into the waste while the high
permeability materials assist in carrying the water away from the cap. Clays used for a barrier should
compact to a hydraulic conductivity of no greater than 1 x 10-6 cm/s and are usually installed at a
thickness of 0.6 metres or greater. Geosynthetic Clay Liners (GCLs) can also be used as a surface barrier.

This technology is applicable for contaminated soil cleanup

Application Requirements: Surface caps can be used for virtually all types of contaminants. They can
be installed as a temporary measure or used as a final remedial alternative. Temporary caps are used
before final closure to minimize generation of leachate until a better remedy is selected. Surface caps
may be applicable for waste masses that are so large that other treatment is not feasible.

Proven Effectiveness/Experience Elsewhere: Surface capping has been effectively used for a long time
to close landfills and its principles can be applied to contaminated industrial sites. Previously installed
caps, however, are sometimes hard to monitor for performance. It is often not possible to determine




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whether the contaminated water or leachate originated as surface water or groundwater. In future caps,
performance can be monitored much more effectively by installing pan lysimeters.

Cost Considerations: Surface caps are generally the least expensive alternative to manage human health
and ecological risks posed by contaminated industrial sites.

Objectives Addressed:

                                  Technical Objectives                                      Measure
                                                                                            Addresses
 1.    Achieve healthy aquatic communities                                                     X
 2.    Reduce fish consumption advisories                                                      X
 3.    Reduce erosion impacts
 4.    Re-establish natural hydrologic process
 5.    Re-establish natural features
 6.    Virtual elimination of toxic contaminants using pollution prevention at source
 7.    Achieve water and sediment objectives in watercourses and waterfront                    X
 8.    Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and spills
 9.    Improve body contact recreation in rivers and reduce beach closures                     X
 10.   Eliminate aesthetic nuisances                                                           X
 11.   Reduce basement flooding
 12.   Reduce sanitary sewer inflow and infiltration
 13.   Protect life and property from flooding

Opportunities Considerations:
· The use of surface capping as a remedial alternative should be seriously considered, especially for
   brownfield sites where contaminated soils have been exposed for years with no responsible parties
   taking the lead to remediate the site. Caps can be installed at these sites as a temporary measure
   while other technologies are assessed for their appropriateness. Alternatively, the caps may be used
   as a final remedial alternative. This would typically involve carrying out a site-specific risk
   assessment to verify that there would be no undue risks by leaving the contaminated soil in-place.
· Surface caps can be used for virtually all types of contaminated soil.

References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




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Bioventing, Enhanced Bioremediation,
Land Treatment, Natural Attenuation,
Phytoremediation
(Contaminated Site Cleanup)
Remediation Type: Source Controls

Primary Mechanism: In-Situ Biological
Treatment (Aerobic and Anaerobic Degradation,
Phyto-accumulation/degradation)

Related WWMPs: N/A

Description: Contaminated sites can include both
                                                               Typical bioventing system
operating and abandoned former industrial
properties (brownfields).       The types of
contaminants at industrial sites can vary,
depending on the types of operations that were
carried out (e.g. metals, VOCs, SVOCs,
pesticides). The focus on contaminated industrial
sites is the remediation of soil to address two
potential pathways in which the river can be
impacted:     1)   surface    run-off    carrying
contaminated soil and 2) leaching of
contaminated soil into the groundwater which
may ultimately migrate and discharge to the river.        Typical enhanced bioremediation system

In-situ biological treatment processes used to remediate contaminated soil include bioventing, enhanced
bioremediation, land treatment, natural attenuation, and phytoremediation. The main advantage of in-situ
biological methods is that the soil can be remediated without being excavated and transported, which
could potentially result in significant cost savings. However, in-situ methods typically require a longer
time period to complete, and it is more difficult to determine whether the contaminants have been
destroyed due to heterogeneities in the soil. Bioremediation is a destruction technique aimed at
stimulating microorganisms in the soil to grow and use the contaminants as food and energy.
Biodegradation can be carried out in aerobic and anaerobic conditions (i.e. to degrade highly chlorinated
compounds).

Bioventing involves stimulating the natural in-situ biodegradation of aerobically degradable compounds
in soil by providing oxygen to the existing microorganisms. This technology uses low air flow rates to
distribute sufficient oxygen to sustain microbial activity.

Enhance bioremediation is a process where indigenous or inoculated microorganisms degrade
contaminants in soil and/or groundwater, converting them to innocuous end products. This remedial
technology typically involves the percolation or injection of ground water or uncontaminated water mixed
with nutrients and saturated with dissolved oxygen



                                                                                  City of Toronto   1 - 115
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Land treatment, also known as landfarming, is a bioremediation technology in which contaminated soils
are tilled and allowed to interact with the soil and climate at the site. Amendments are added if necessary.


Natural attenuation of contaminated soils involves the reduction of contaminant concentrations by natural
processes including biodegradation, dilution, dispersion, volatilization, adsorption, and chemical reactions
with soil materials. Natural attenuation is not a “technology” per se, and there is significant debate
among technical experts about its use at hazardous waste sites.

Phytoremediation is a process that uses plants to remove, transfer, stabilize, and destroy contaminants in
soil and sediment. There are four different mechanisms that comprise phytoremediation, including
enhanced rhizosphere biodegradation, phyto-extraction, phyto-degradation, and phyto-stabilization.
Enhanced rhizosphere biodegradation occurs in the soil adjacent to the plant roots. Phyto-accumulation is
the uptake of contaminants by plant roots into the shoots and leaves. Phyto-degradation involves the
metabolism of contaminants within plant tissues. Phyto-stabilization is a process where chemical
compounds are produced by plants, which immobilize the contaminants at the interface of roots and soil.

These technologies are applicable for contaminated soil cleanup.

Application Requirements: Although not applicable to all organic compounds, the various
bioremediation techniques have been successful in treatment of soils contaminated by petroleum
hydrocarbons, solvents, pesticides wood preservatives, and other organic chemicals. Bioremediation is
not applicable for treating inorganic contaminants. Also, in-situ bioremediation methods may not be
applicable for contaminants where the breakdown product is more toxic than the parent compound (e.g.
TCE to vinyl chloride). Vinyl chloride, however, can be broken down further if aerobic conditions are
created.

Bioventing techniques are applicable for remediating soils contaminated with petroleum hydrocarbons,
non-chlorinated solvents, some pesticides, wood preservatives, and other organics. The applicability of
bioventing is limited by shallow watertables, saturated lenses, or low permeability soils. Also, extremely
low moisture content and low temperatures may hinder the biodegradation process, and effectiveness of
bioventing.

The use of enhanced bioremediation is not applicable in clay soils, highly layered, or heterogeneous
subsurface environments because of oxygen transfer limitations. Also, high concentrations of heavy
metals, highly chlorinated organics, long chain hydrocarbons, or inorganic salts are likely to be toxic to
the microorganisms.

Land treatment has been successfully applied to treat diesel fuel, No. 2 and No. 6 fuel oils, JP-5, oily
sludge, wood-preserving wastes (PCP, PAHs, and creosote), coke wastes, and certain pesticides. A large
amount of space is required to use land treatment techniques and depth of treatment is limited to the depth
of achievable tilling (approximately 0.45 metres).

Target contaminant groups for natural attenuation are VOCs, SVOCs, and fuel hydrocarbons. Certain
pesticides may also be amenable to natural attenuation. The use of this process as a remedial alternative
usually requires modelling and evaluation of contaminant degradation rates and migration pathways. In
addition, a sampling program must be implemented to verify that clean up is proceeding at the predicted
rates.




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Phytoremediation is applicable for remediation soils contaminated with metals, pesticides, solvents,
explosives, crude oil, PAHs, and landfill leachates. Soil remediation using this technique is limited to
shallow soils (i.e. within the root zone). High concentrations of hazardous compounds can be toxic to the
plants. Phytoremediation not applicable during the winter months, and is not effective for strongly sorbed
(e.g. PCBs) and weakly sorbed contaminants.

Proven Effectiveness/Experience Elsewhere: Although bioventing is considered an emerging
technology, the US Air Force has completed testing at 117 sites, with more than 90 pilot systems now
operating at 41 USAF installations.

Enhanced bioremediation has been selected for remedial and emergency response actions at an increasing
number of Superfund sites.

Numerous full-scale land treatment operations have been implemented, particularly for sludges produced
by the petroleum industry.

Natural attenuation has been selected by the Air Force Center for Environmental Excellence (AFCEE) for
remediation at 45 USAF sites.

Phytoremediation is considered an emerging technology. It has been successfully tested at many sites in
the US, but full-scale applications are limited. The USEPA is testing phytoremediation in the Superfund
Innovative Technology Evaluation (SITE) Program at sites in Oregon, Utah, Texas, and Ohio.

Cost Considerations: Key factors that affect the cost include contaminant type and concentration, soil
permeability, well spacing and number, pumping rate, and off-gas treatment. In general, petroleum
hydrocarbons can be readily bioremediated at relatively low costs by stimulating indigenous
microorganisms with nutrients. The costs for natural attenuation consist of modelling contamination
degradation rates and regular soil sampling to verify the process. Cost information for phytoremediation
is limited, as it is an emerging technology.




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SOURCE CONTROLS


Objectives Addressed:

                                  Technical Objectives                                      Measure
                                                                                            Addresses
 1.    Achieve healthy aquatic communities                                                     X
 2.    Reduce fish consumption advisories                                                      X
 3.    Reduce erosion impacts
 4.    Re-establish natural hydrologic process
 5.    Re-establish natural features
 6.    Virtual elimination of toxic contaminants using pollution prevention at source
 7.    Achieve water and sediment objectives in watercourses and waterfront                     X
 8.    Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and
       spills
 9.    Improve body contact recreation in rivers and reduce beach closures
 10.   Eliminate aesthetic nuisances                                                            X
 11.   Reduce basement flooding
 12.   Reduce sanitary sewer inflow and infiltration
 13.   Protect life and property from flooding

Opportunities Considerations:
· Considering that contaminated soil can be treated without being excavated and transported off-site
   (potentially lower costs), the use of in-situ bioremediation techniques should be assessed. However,
   the application of these types of technologies will highly depend on the site-specific subsurface
   conditions and would have to be evaluated on a case-by-case basis (e.g. permeability, homogeneity,
   etc.).
· There are a number of advantages to natural attenuation, and its use for remediation of contaminated
   industrial sites should be assessed. These include less generation of remediation wastes, less
   intrusive, may be applied to all or part of a site, and overall costs will likely be lower than active
   remediation.
· Bioventing is targeted for remediation of soils contaminated with petroleum, non-chlorinated
   solvents, some pesticides, wood preservatives, and other organics. Effectiveness is limited by
   shallow watertables, saturated lenses, or low permeability soils.
· Enhanced bioremediation is not applicable in clay soils, highly layered, or heterogeneous subsurface
   environments. May not be applicable in high concentrations of heavy metals, highly chlorinated
   organics, long chain hydrocarbons, or inorganic salts.
· Land treatment is applicable for remediation soils contaminated with diesel fuel, No. 2 and No. 6 fuel
   oils, JP-5, oily sludge, wood-preserving wastes, coke wastes, and certain pesticides. Applicable to a
   dept of approximately 0.45 metres.
· Natural attenuation is applicable for soils contaminated with VOCs, SVOCs, and fuel hydrocarbons.
· Phytoremediation is applicable to a wide variety of contaminants including metals, pesticides,
   solvents, explosives, crude oil, PAHs, and landfill leachates. Phytoremediation is a seasonal
   technology and is limited to shallow contaminated soils.

References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




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                                                                                     SOURCE CONTROLS




Electrokinetic Separation, Soil Flushing,
Soil Vapour Extraction,
Solidification/Stabilization
(Contaminated Site Cleanup)
Remediation Type: Source Controls

Primary Mechanism: In-Situ Physical/Chemical Treatment

Related WWMPs: N/A

Description: Contaminated sites can include both operating and abandoned former industrial properties
(brownfields). The types of contaminants at industrial sites can vary, depending on the types of
operations that were carried out (e.g. metals, VOCs, SVOCs, pesticides). The focus on contaminated
industrial sites is the remediation of soil to address two potential pathways in which the river can be
impacted: 1) surface run-off carrying contaminated soil and 2) leaching of contaminated soil into the
groundwater which may ultimately migrate and discharge to the river.

In-situ physical/chemical treatment technologies used to remediate contaminated soil at industrial sites
include electrokinetic separation, soil flushing, soil vapour extraction, and solidification/stabilization.
Physical/chemical treatment processes utilize the physical properties of the contaminants or the
contaminated medium to chemically convert or separate the contamination. The main advantage of in-
situ biological methods is that the soil can be remediated without being excavated and transported, which
could potentially result in significant cost savings. In-situ chemical/physical treatment is typically cost
effective and requires less time to complete than in-situ biological treatment.

Electrokinetic Remediation (ER) involves the application of a low-intensity direct current through soil
between ceramic electrodes that are divided into a cathode array and an anode array. This mobilizes
charged species, causing ions and water to move toward the electrodes. Metal ions, ammonium ions, and
positively charged organic compounds move toward the cathode while anions (e.g. chloride, cyanide,
fluoride, and nitrate) flow towards the anode.

In-situ soil flushing is a process in which contaminants are extracted from the soil with water or other
suitable aqueous solutions. This is accomplished by passing the extraction fluid through the soils using
injection or infiltration process. Contaminants are leached into the groundwater, which are then extracted
and treated. Cosolvent flushing involves injecting a solvent mixture (water and a miscible organic solvent
such as alcohol) into either the vadose zone or saturated zone to extract organic contaminants.

Soil vapour extraction (SVE) is a technology in which a vacuum is applied in the vadose zone soil to
induce the controlled flow of air and remove volatile and some semi-volatile contaminants from the soil.
Vertical extraction vents are typically used at depths of 1.5 metres or greater, and success has been shown
in vents as deep as 91 metres. Horizontal extraction vents can also employed, depending on contaminant
zone geometry, drill rig access, or other site-specific factors.




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Solidification/stabilization is a remediation technology in which contaminants are physically bound or
enclosed within a stabilized mass (solidification), or chemical reactions are induced between the
stabilizing agent and contaminants reduce their mobility (stabilization). Leachability tests are typically
conducted to measure the immobilization of the contaminants. Solidification/stabilization can be
accomplished both in-situ and ex-situ (prior to disposal).

These technologies are applicable for contaminated soil remediation.

Application Requirements: Targeted compounds for electrokinetics are heavy metals, anions, and polar
organics in soil. Concentrations that can be treated range from a few ppm to tens of thousands ppm. This
technology is most applicable in low permeability soils (i.e. clays), which are saturated or partially
saturated.

The target contaminant group for soil flushing is inorganics, including radioactive contaminants. VOCs,
SVOCs, fuels, and pesticides can be treated with soil flushing, but may not be cost-competitive with
alternative technologies for these contaminant groups. The applicability and effectiveness of this
technology is limited in low permeability soils. Also, the potential of washing the contaminants beyond
the capture zone and introduction of surfactants to the subsurface concern regulators.

In-situ SVE is targeted at remediating soil contaminated with VOCs and some fuels. This technology is
typically applicable only to volatile compounds with a Henry’s law constant greater than 0.01 or a vapour
pressure greater than 0.5 mm Hg. In-situ SVE will not remove heavy oils, metals, PCBs, and dioxins.

The target contaminant group for in-situ solidification/stabilization is generally inorganics, including
radionuclides. The Auger/Caisson and Reagent/Injector Head Systems have limited success against
SVOCs and pesticides, no effectiveness against VOCs. The depth of contaminants may limit the
applicability of this technology. Treatability tests are required, as certain wastes are incompatible with
variations of this process.

Proven Effectiveness/Experience Elsewhere: There have been few, if any, commercial applications of
electrokinetic remediation in the US. In 1996, the US Department of Defence carried out lead extraction
demonstration study using this technology. The pilot-scale results showed that lead was reduced from
4,500 ppm to 300 ppm in 30 weeks.

Soil flushing is a developing technology, which has had limited use in the US. This technology has been
selected as part of the source control remedy at 12 Superfund sites.

Auger/Caisson and Reagent/Injector Head Systems have demonstrated the ability to reduce the mobility
of contaminated waste by greater than 95%. The long-term effects of weathering, groundwater
infiltration, and physical disturbances can significantly affect the integrity of the stabilized mass and
contaminant mobility.

Cost Considerations: Key factors affecting the costs include the quantity of soil to be treated,
conductivity of the soil, type of contaminant, spacing of electrodes, and the type of process design
employed. The cost for soil flushing varies and is highly dependent on the type and concentrations of
surfactants used (if at all used). Site-specific factors affecting the cost of in-situ SVE include the size of
the site, nature and amount of contamination, and the hyrogeological setting.




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Objectives Addressed:

                                   Technical Objectives                                       Measure
                                                                                              Addresses
 1.    Achieve healthy aquatic communities                                                       X
 2.    Reduce fish consumption advisories                                                        X
 3.    Reduce erosion impacts
 4.    Re-establish natural hydrologic process
 5.    Re-establish natural features
 6.    Virtual elimination of toxic contaminants using pollution prevention at source
 7.    Achieve water and sediment objectives in watercourses and waterfront                          X
 8.    Eliminate sanitary discharges in SSO, CSOs, bypasses, cross connections and
       spills
 9.    Improve body contact recreation in rivers and reduce beach closures
 10.   Eliminate aesthetic nuisances                                                                 X
 11.   Reduce basement flooding
 12.   Reduce sanitary sewer inflow and infiltration
 13.   Protect life and property from flooding

Opportunities Considerations:
· Similar to in-situ bioremediation technologies, in-situ chemical/physical techniques can treat
   contaminated soil without requiring excavation and off-site disposal (potentially lower costs).
   Therefore, in-situ chemical/physical techniques should be assessed for its applicability at sites within
   the Study area. However, the application of these types of technologies will highly depend on the
   site-specific subsurface conditions and would have to be evaluated on a case-by-case basis (e.g.
   permeability, homogeneity, etc.).
· Electrokinetics is targeted for remediation of soils contaminated with heavy metals, anions, and polar
   organics. Most applicable in low permeability soils.
· Soil flushing is applicable for remediation of soils contaminated with inorganics. Effectiveness is
   limited in low permeability soils.
· In-situ SVE is targeted at remediating soils contaminated with VOCs and some fuels. Applicable for
   VOCs with a Henry’s law constant greater than 0.01 or a vapour pressure greater than 0.5 mm Hg.
· Solidification/stabilization is applicable for remediating soils contaminated with inorganics. The
   depth of contaminants may limit the applicability of this technology.

References:
· McBean, E., Farquhar, G., and Rovers, F., Solid Waste Landfill, Engineering and Design, Prentice
   Hall Canada, 1995
· U.S. EPA, Federal Remediation Technologies Roundtable Web Site, (URL: http://www.frtr.gov)




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Example of Typical Electrokinetic Remediation System




Example of Typical Soil Flushing System




Example of Typical Soil Vapour Extraction System




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                                                          SOURCE CONTROLS


Example of Typical Solidification/Stabilization System




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