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

2. 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)

3. 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

4. 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

5. MS4 Permit & TMDL Designation of additional MS4s in TMDL watersheds
Extend past areas to boundaries of New York City drinking water watershed East of Hudson
Extend Eastward in Long Island
Peconic Estuary TMDL designates Eastern Long Island

6. 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).

8. 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

10. 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)

11. 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) yr storm, post flow rate less than or equal to predevelopment flow rate

12. 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.

13. 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

14. 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

15. 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

16. 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 ~ 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

17. 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

18. 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

19. 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)

20. 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

22. 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

24. 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

27. 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

29. 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

30. Questions