NYSDEC Stormwater Permits TMDL Conditions and Retrofit Options Shohreh Karimipour, P.E.

NY- Status of Stormwater Permits Construction (6860) & MS4 (500) Renewed April 2008 2 year term Detailed and prescriptive Address TMDL watersheds Differentiate Non-Traditional/Land use MS4s Multi Sector (1200) No Exposure (550)

NY- Status of Stormwater Permits One Phase 1 MS4s (NYC) 495 Phase 2 MS4 354 annual reports (2008) indicate 275 Adopted Construction Law 305 Inter-municipal cooperation 48 Received public comments 302 Started plan review 304 Completed outfall mapping MS4 Permits City, Town, Village 412 County 33 Federal, State 25 School District 14 Other Entities 16

NY- Status of Stormwater Manuals Standards and Specification for E&SC SW Management Design Manual Redevelopment Projects Enhanced Phosphorus Removal Better Site Design Decompaction Guidance Manual For Local Officials MS4 Model Laws Poll. Prevention Mapping Guidance

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

Additionally Designated Areas Criterion 1: MS4s discharging to waters for which an EPA-approved TMDL required reduction of a pollutant associated with stormwater beyond what can be achieved with existing programs (and the area is not already covered under automatic designation as UA).

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)

Standard Unified Sizing Criteria (Chapter 4 Design Manual) Water Quality Volume (WQv) – Treat 90 % storm Channel Protection Volume (CPv) – Detain 1 yr storm Overbank Flood Flow (Qp) - 10 yr storm, post flow rate less than or equal to predevelopment flow rate Extreme Storm Flow (Qf) - 100 yr storm, post flow rate less than or equal to predevelopment flow rate

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 Requirements in 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 Requirement In 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 EPA required EOH Plan First draft public review in 2006 First deadline for retrofit plan in EOH Implementation plan would provide direction for what would be approvable Follow similar process for other watersheds

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 Targeted Education and Outreach

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 Targeted Education and Outreach

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 Targeted Education and Outreach 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. Targeted Education and Outreach 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

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