Regional Watershed Management Plans - rowan

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					Regional Stormwater Management
            Planning

            Craig McGee
 Camden County Soil Conservation District
          Rowan University
            April 4, 2003
    Development of Regional
 Stormwater Management Plans
Plans are being prepared for five watersheds in
              southern New Jersey:
                Maurice River
                Masons Creek
                  Little Creek
                 Cooper River
              Smithville Drainage
 What is a Regional Stormwater
      Management Plan?
Regional or Site Specific Stormwater
Management
Site Specific BMP Recommendations
Watershed Assessment for Stormwater Related
Issues
Restoration Recommendations
Workable Management Plan
Implementation Plan
Regional Stormwater Management Plan
 Characterization and Assessment
   Mapping of features
   Assessment of Stream Corridor and Watershed
   Features
   Hydrologic and Hydraulic Modeling
   Metering and Monitoring
   Stakeholder Input
   Existing Studies Review
Regional Stormwater Management Plan
 Management Plan
   Regional management measures for new
   development
   Improvements of existing stormwater facilities
   Restoration strategies
   Low Impact Development Strategies
   Incorporate Stakeholder Concerns
   Implement Proposed DEP Stormwater Regs
Regional Stormwater Management Plan
 Implementation Plan
   Approval of NJDEP
   Adopted by Stakeholders
   Adopted by PAC
   May Replace Existing Stormwater Rules
   Phase II Stormwater Regulations
   Municipal Adoption & Implementation
Watershed Assessment
 Significant Obstructions
 Stormwater Outfalls
 Stream Corridor Evaluation
 Stormwater Facilities
 Hydrologic/ Hydraulic Evaluations
Stream Obstructions
                      Obstructions were
                      located w/ GPS,
                      measured, photographed
                      and described
                      Obstructions include
                      natural debris or beaver
                      dams
Stormwater Outfalls
                      SWO located in field w/
                      GPS
                      Data collection included
                      size, condition and
                      discharge point
                      This Data Needed by
                      Municipalities for Phase
                      II Stormwater Permitting
Stream Corridor Evaluation
                    Reach Assessment form
                    Channel Status/Evolution
                    Buffer Assessment
                    Flow Status
                    Streambank and Bed
                    Erosion
     Reach
 Delineation and
   Evaluation
•Customized
Evaluation Form
•Redrawn Stream Map
•Extensive Field Work
Stormwater Facilities
                        Detention Basin Location
                        and Condition
                        Water Quality Basins or
                        BMP
                        Suitability for Retrofit
                        Stormwater Systems
Hydrologic/ Hydraulic
 Overall Baseline Hydrology
 Detailed Hydraulic Modeling of Specific Reaches
 Detailed Hydrology Where Needed
 Representative Sub-Watersheds
 Recharge vs. Impervious Cover
 NRCS Runoff Methods
   CN,Tc, Reach Routing, Storage Routing
Drainage Area Boundaries
                   Based on Major Stream
                   Junctions or Road
                   Culverts
                   Main Stem Model will be
                   Calibrated to USGS
                   gage at Haddonfield
                   Detailed Models of
                   Specific Areas as
                   Needed
Baseline Hydrology
    Specific Modeling Projects

Source Control Investigation
Effective Area Curve Number Development
Recharge Analysis Based on Zoning
   Source Control Investigations
Small Watershed Studied in Detail
HEC-HMS Hydrologic Model
Detailed HEC-RAS Model of Receiving Stream
Modifications to Existing Stormwater Facilities
Disconnection of Impervious Area
Recharge of Roof Areas
Changes in Flow in Receiving Stream?
          Brookstone Ditch
Urbanized Sub Watershed
Mix of Landuse & Stormwater Control
Various Generations of Stormwater BMP
Severely Degraded Channel
Municipally Owned & Maintained
Recent Hard Armor Restoration
Extensive Data (HEC-RAS) Available
Brookstone HEC-HMS
Brookstone HEC-RAS
               •Route Current &
               Modified
               Hydrographs
               through Stream
               Channel
               •Unsteady Flow
               •Observe Changes
               in Peak Rates,
               Volume & Velocity
Effective Area Curve Number
        Development
               „Non-Contributing‟ Areas
               Consider Connected
               Impervious & Contiguous
               Areas Only
               Interflow?
               Calibration to Stream
               Gage
          Recharge Analysis
Use HSG to Calculate
Recharge
Map Depicts Average
Annual Recharge
           Recharge Analysis
Prepare Zoning Maps
from Municipal Data
Require Significant
Legwork to Collect Data
Recharge Analysis
          Combine Recharge &
          Zoning to Identify Areas
          of Concern
          Consider Zoning
          Ordinances to Protect
          Recharge Capacity
         Cooper River
    Management Plan Features
Stream Corridor Restoration
Redevelopment Guidance
High Frequency Storm Management
Reference Reach Designation
Retrofit Existing Facilities
Restoration of Degraded Features
Low Impact Development and Restoration
NJDEP Stormwater Rule Compliance?
Stream Corridor Restoration
                    Evaluate Reference
                    Reaches
                    Classify Degraded
                    Reaches using Rosgen
                    Method and CEM
                    Restoration Alternatives
                    Prioritization
                    Pitfalls & Problems
Stream Restoration
                     Bioengineering
                     “Hard Armor”
                       Gabions
                       Geo-Tubes
                       Rip Rap
                     Grade Stabilization
                     Channel Reconstruction
Redevelopment Guidance
                 Stormwater Guidelines
                 for Redevelopment
                 Tracts
                 Increase Recharge
                 Decrease Connected
                 Impervious Cover
                 Supplemental – Regional
                 Stormwater Storage?
High Frequency Storm Management
                  Channel Forming
                  Discharge
                  Designing for 2Yr Storm
                  only Manages 3% of
                  Annual Rainfall
                  Consider Initial
                  Abstraction
                  Low Impact Design
                  Methods
Reference Reach Designation
                   Evaluate and Classify
                   Reach where “it works”
                   Rosgen‟s Classification
                   and CEM evaluation
                   Apply Same Channel
                   Geometry to Restorable
                   Reaches
Retrofit of Existing Facilities
                       Retrofit Flood Control
                       Basins
                       Add Water Quality
                       Add Infiltration Capacity
                       Disconnect Impervious
                       Area
                       Retrofit Parking lots,
                       Outfalls, etc
Maintain Culverts
                    Culverts provide grade
                    control
                    Undersized Culverts
                    provide some storage
                    Consider Outlet
                    Structures to Pass High
                    Flows & Maintain Current
                    Geometry for Low Flows
Restoration of Degraded Features

                   Streambank Restoration
                   Restoration Planning
                   Channel Evolution
                   Structure Repair
                   Repair of “Repairs”
Low Impact Development
                  Reduce Impervious
                  Cover
                  Disconnect Imp. Areas
                  Maintain Natural
                  Vegetation
                  Require Recharge
                  Manage Hi Frequency
                  Storms (<1.5 inches)
            Lessons Learned
Watershed Assessment Critical
Adapt Plans Based on Findings
Unknowns Increase Project Planning Difficulty
Detailed Procedures Insure Uniformity & Efficiency
Steep & Multifaceted Learning Curve
Have Fun
Craig Mc Gee – Project Director

 Camden Soil Conservation District
   423 Commerce Lane, Suite 1
      West Berlin, NJ 08091
          (856) 767-6299
        fax (856) 767-1676
  craig.mcgee@camdenscd.org

				
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posted:7/26/2011
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