nys department of environmental conservation nysdec stormwater permits tmdl conditions and retrofit...

NYS Department of Environmental Conservation

NYSDEC Stormwater Permits TMDL

Conditions and Retrofit Options

Shohreh Karimipour, P.E.


MS4 Permit & TMDL

• Designation of additional MS4s in TMDL watersheds

• 2003 - Extend past areas to boundaries of New York City drinking water watershed East of Hudson

• 2003 - Extend Eastward in Long Island

• 2008 - Peconic Estuary TMDL designates Eastern Long Island


NYC EOH Watershed Improvement Strategy

Local Requirement for E&SC - 5,000 ft2 to 1 acre (12/31/2009)

Local SWPPP Review Against Enhanced P Removal (9/30/2008)

Map entire storm sewer system over 5 years

Retrofit plan and schedule 3/9/2009 (alone), 12/31/2009 (RSE)

Septic Inspections, Maintenance, and Rehabilitation/3 Yr.

Targeted Education and Outreach

Specific System Maintenance Requirements

Specific Turf Management Requirements

Leaf and Yard Waste Control Requirements


Loading Assessments

• By 1/8/2013 model relative changes in load to impaired waters (no TMDL) with non-negligible changes to land areas or practices

• By 1/8/2013 model to assess progress in reducing the pollutant of concern to meet TMDL

• Modeling alternatives in responsiveness summary (Appendix D)


Enhanced Phosphorus Removal Sizing Criteria

Sizing Criteria for Enhanced Phosphorus Removal

Water Quality (WQv)

WQv = estimated runoff volume (acre-

feet) resulting from the 1-year, 24-hour design storm over the post development watershed

Evaluate and implement hydrologic source control where feasible

Quantity Controls (Cpv, Qp, Qf)

Refer to existing requirements*Cpv

Integrated in extended detention systems

Need additional storage in flow through systems.


Retrofits

• Retrofits are modifications or additions to existing infrastructure to reduce pollutant loadings. Examples (pp72 and 73): – Better Site Design Approaches– Storm Sewer Rehabilitation– Stabilizing Dirt Roads– Conversion of Dirt Parking to Pervious Pavement– Conversion of Dry Ponds to Detention Ponds or Wetlands– Converting Abandoned Buildings to Open Space or SMP– Control of Downstream Erosion Effects– Direct Control Erosion Effects (Plunge Pool, Velocity Dissipaters)– Upgrade of Existing Conveyance to Provide Quality and Quantity Control– Reforestation


Retrofit Permit Requirementsin April, 08 MS4 Permit

• Identify sites with problems

• Choose projects based on:– Pollutant reduction potential– Use of proven technologies– Economic feasibility

• Procedures for design, permits, funding, O&M

• Approvable plans, schedules and funding sources


Retrofit Permit RequirementIn April, 08 MS4 Permit

• East of Hudson MS4s acting alone submit approvable plan and schedule by March 9, 2009

• East of Hudson MS4s in RSE submit by December 31, 2009

• Onondaga, Greenwood Lake, Oyster Bay, Peconic MS4s submit by March 9, 2011


DEC Retrofit/Modeling Paper

• Basis for Retrofit Section of TMDL Implementation

• Short term expectations: simpler retrofits- e.g. ditches to dry swales, erosion repairs and disconnecting rooftops ~ 0.3 - 0.5 lb/acre/yr

• Long term expectations: more sophisticated retrofits - more sophisticated targeting - considering cost effectiveness

• Load reductions for retrofits can be assigned using WTM or Win-SLAMM


Other Key Points

• Older TMDLs do not distinguish MS4 loads from non-point source

• MS4 load reduction would be achieved with Retrofits and non-structural BMPs

• Retrofits may include Redevelopment or routine system upgrades

• Guidance: Urban Stormwater Retrofit Practices Manual

• Desktop Assessment & Retrofit Reconnaissance Investigation


East of Hudson TMDL Implementation Plan Concepts

• Establish sustainable annual mass reductions and maximum 15 year schedule

• Apportion reductions by MS4 – for Phosphorus, base apportions on high intensity development

• Allow for bubble or individual load reductions

• Reductions credited based on modeling projects

• Re-evaluate every five years ( use monitoring data/modeling)


Greenwood Lake Watershed Improvement Strategy

Local SWPPP Review Using Enhanced P Removal by 9/30/2008

Watershed Based Retrofit plan and schedule 3/9/2011

Septic Inspections, Maintenance, and Rehabilitation/3 Yr



Onondaga Lake Watershed Improvement Strategy

Local SWPPP Review Using Enhanced P Removal by 9/30/2008

Watershed Based Retrofit plan and schedule 3/9/2011



Oyster Bay and Peconic Watershed Improvement Strategy (Pathogens)

Watershed Based Retrofit plan and schedule by 3/9/2011

Septic Inspections, Maintenance, and Rehabilitation/ 3 Yr


Pet Waste Control

Goose Population Management


Peconic Watershed Improvement Strategy (Nitrogen)

Watershed Based Retrofit plan and schedule by 3/9/2011

Septic Inspections, Maintenance, and Rehabilitation/3 yr.


Specific Turf Management Requirements


Other TMDL Implementation Plans

• EPA required TMDL Plans • Follow similar process for other

watersheds

• Potential change of criteria at end point• Mostly phosphorus limited watersheds

– Albany area, Monroe Co., down state

• Implementation plan would provide direction for what would be approvable


Questions

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