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Enhanced Phosphorus Removal Standards Workshop June 11, 2008 Fishkill, NY

NEW YORK STATE DEPARTMENT OF ENVIRONMENTAL CONSERVATION. Enhanced Phosphorus Removal Standards Workshop June 11, 2008 Fishkill, NY. The Project Team.

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Enhanced Phosphorus Removal Standards Workshop June 11, 2008 Fishkill, NY

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  1. NEW YORK STATE DEPARTMENT OF ENVIRONMENTAL CONSERVATION Enhanced Phosphorus Removal Standards WorkshopJune 11, 2008Fishkill, NY

  2. The Project Team Marcus Quigley, P.E. Project Manager Eric Strecker, P.E., Principal-In-Charge GeoSyntec ConsultantsRobert Pitt, Senior Technical Specialist and Technical ReviewNYS DEC, Project ManagementTechnical Advisory Group (TAG) NYCDEP NYSSWCC NYSOAG River Keepers (CEA) Insite Engineering

  3. Workshop Agenda 9:00 - 9:05 am 9:05 – 9:20 am • Introduction • Overview of Existing Standards • Enhanced Criteria • Background • Approach • Theoretical Basis • Development of Goals • Analysis to Support Goals • Break • Design Standard • Volumetric Control • Channel Protection • Infiltration Requirements • Source Control, Better Site Design, and Low Impact Development • Lunch • Examples • Conventional Design • Better Site Design 9:20 – 10:30 am 10:30-10:45 am 10:45-11:05 am 11:05-12:00 pm 12:00 pm -1:00 pm 1:00 -3:00 pm

  4. STORMWATER REGULATORY REQUIREMENTS: New York City Watershed

  5. Stormwater: runoff flowing over the ground during or immediately after a rainfall or snow event; runoff can transport a variety of pollutants that have accumulated on the surface and deposit them into a storm sewer system or waterbody

  6. Land Development: the altering of landforms from a natural or semi-natural state for the purpose of making the area of land more profitable, productive or useful

  7. STORMWATER Impacts of Stormwater Runoff from Land Development • More Frequent Flooding • Increased Intensity of Flood Events • Erosion and Sedimentation • Degradation of Aquatic Habitat • Degradation of Water Quality in Streams, Lakes, Reservoirs and Wetlands

  8. NYC WATERSHED REGULATIONS Prior to 1997, NYC regulatory authority with respect to construction activity in the Watershed was derived from the 1953 Regulations; NYC had no direct approval authority over land development other than sewage disposal systems

  9. NYC WATERSHED REGULATIONS NYCDEP regulatory authority with respect to stormwater runoff is drawn from Section 18-39 of the 1997 NYC Watershed Rules and Regulations Section 18-39: • Established NYCDEP authority to regulate the management and treatment of stormwater runoff from construction activities; • Established standards for the delineation and protection of watercourses; • Codified prohibitions regarding the construction of impervious surfaces.

  10. NYC WATERSHED REGULATIONS NYCDEP administers Section 18-39 and its oversight of land use activities in the watershed via the review and approval of formal permit applications Typical land use activities requiring NYCDEP review and approval: • Residential • Commercial • Institutional (schools/hospitals/houses of worship) • Utility • Transportation

  11. NYC WATERSHED REGULATIONS Section 18-39 permits/approvals include: • Stormwater Pollution Prevention Plans (SPPP) • Individual Residential Stormwater Permits (IRSP) • Watercourse Crossing, Piping and Diversion Permits (CPDP).

  12. NYC WATERSHED REGULATIONS SPPP thresholds applicable to typical construction activities: • Two or more acres of land clearing or grading within 100 feet of a watercourse or state wetland or on a slope in excess of 15% EXAMPLE: Residential site work involving the exposure of soil to the forces of nature

  13. NYC WATERSHED REGULATIONS SPPP thresholds applicable to typical construction activities: • Construction of a new industrial, municipal, commercial or multi-family residential project resulting in 40,00 square feet of new impervious surface EXAMPLE: Conversion of wooded parcel to new senior housing complex

  14. NYC WATERSHED REGULATIONS SPPP thresholds applicable to typical construction activities: • Expansion of existing impervious surfaces within 100 feet of a watercourse or state wetland EXAMPLE: Expansion of asphalt parking lot at a strip mall immediately adjacent to a water body

  15. NYC WATERSHED REGULATIONS SPPP: What is it? • A “plan” that includes an engineering report and construction drawings describing and depicting how stormwater runoff will be managed on-site both during and after construction

  16. NYC WATERSHED REGULATIONS SPPP Requirement: • Pollutant Loading Analyses = pre- versus post-development comparison of select pollutant loading rates, including phosphorus, nitrogen and total suspended solids

  17. NYC WATERSHED REGULATIONS SPPP Practice Selection: • Hierarchy of Management Practices = Infiltration / Retention / Extended Detention • Adjunct Management Practices = Proprietary hydrodynamics, sand filters and bioretention basins are among a number of practices assigned no pollutant removal efficiency

  18. NYC WATERSHED REGULATIONS SPPP Design Standards: • Treatment Volume = first ½ inch of runoff or the volume of runoff generated by the 1 year / 24 hour storm event, whichever is greater, from all disturbed areas • Treatment Volume *Phosphorus Restricted Basins* = the volume of runoff generated by the 2 year / 24 hour storm event from all disturbed areas

  19. NYC WATERSHED REGULATIONS Impervious Surface Prohibitions • Section 18-39 generally prohibits the construction of new impervious surfaces within 300 feet of a reservoir, reservoir stem or controlled lake and within 100 feet of a watercourse or state regulated wetland

  20. Questions? Matt Giannetta 914.742.2028 mgiannetta@dep.nyc.gov

  21. Enhanced Criteria Empirical and Theoretical Basis for Standards

  22. Defining Enhanced • Performance Criteria • Hydrologic and Hydraulic • Sizing and hydraulics are the keys to achieving desired performance • Water Quality • Goal in the Receiving Water • Mass Limited (Lake and Ponds) • Concentration Limited (Streams and Rivers) • Maintenance • Sediment removal and control • Vegetation control • Landscaping • Gross floatable organics and litter and garbage (operations)

  23. Core Approach –State of the Practice Continuous Simulation H&H, Solids, particulate P Assess Performance of Existing Design Methods Existing Design Method and Variables Assess Performance of Proposed Alternative Methods • Translate back to simple sizing approach by modifying WQv criteria and other established design variables • Provide non-Sizing design criteria for enhanced P treatment Establish Treatment Goals Establish Design Variables to Meet Goal Empirical, Theoretical, and Statistical Analysis Assess Available Performance Data Check consistency of Data with Model Assess Available Data and Theory to Select Unit Processes for Enhanced Phosphorus Removal (Specially Dissolved Fractions)

  24. Phosphorus and Treatability • Particulate vs. dissolved forms • Particulate size or settling velocities classes vs. mass of phosphorous • Empirical Analysis

  25. Empirical Analysis Data Sources • NSW Database (Pitt) • International Stormwater Best Management Practices Database (www.bmpdatabase.org) • Numerous Site Level Studies

  26. 10.000 1.000 Effluent Total Phosphorus EMCs (mg/L as P) 0.100 0.010 0.001 DB GS HD MF RP WB WC BMP Category Total Phosphorous (mg/L as N) Supplement Particulate P Goal (0.1 mg/L) Effluent Total Phosphorous by BMP Category

  27. 1.000 0.100 Effluent Dissolved Phosphorus EMCs (mg/L as P) 0.010 RP WB WC BMP Category Dissolved Phosphorous (mg/L as N) Supplement Dissolved P Goal (0.06 mg/L) Effluent Dissolved Phosphorous by BMP Category

  28. Defining Performance as a Function of BMP Treatment Volume and/or Rates • Continuous simulation modeling to generate design nomographs for assessment of potential modifications to design criteria • Depart from design storm descriptions for assessment of results • Goal of having final rules be simple to implement (could be design storm)

  29. Summary of Analysis • Evaluated Wet Pond (P-2) and Wet Extended Detention Pond (P-3) • Design Factors considered: • WQv • Percent permanent pool (ED Ponds) • Draw-down time (ED Ponds) • Results: • WQv has significantly greater influence over other factors

  30. Continuous Simulation Analyses Performed to Ascertain Performance

  31. Outlet riser Overbank Protection volume (Qp-10) Overbank Protection outlet Channel Protection volume (Cpv) Extended Detention Channel Protection outlet Extended Detention outlet Water quality volume (WQv) Permanent Pool Outlet barrel Wet Extended Detention Pond • WQv divided btw. Permanent Pool and Extended Detention volume • Wet Pond • WQv = 100% Permanent Pool • No Extended Detention outlet

  32. Treatabilty of Phosphorus

  33. Association of Phosphorousand TSS • Research by Pitt, et al indicates that particles less than 10 µm have higher associated phosphorous concentrations than larger particles • Chapter 10 analysis addresses particle sizes 4 – 25 µm • Assigned a weighted Phosphorous concentration based on distribution of particle sizes

  34. Wet PondParticulates removal Non-P Limited Design Standard (WQv = 1.35 ac-ft)

  35. Particle Size Distributions

  36. Wet PondParticulate Phosphorus Treatment Non-P Limited Design Standard (WQv = 1.35 ac-ft)

  37. Wet Extended Detention PondParticulate Phosphorus Treatment (median particle size distribution) Non-P Limited Design Standard (WQv = 1.35 ac-ft)

  38. Phosphorus Treatment versus WQv Size

  39. Sizing Analysis Approach • Developed two test watersheds • Difference: 80% impervious, 20% impervious • Both are 8 acres • Both are 75% C soils, 25% D soils • Also developed corresponding pre-development watershed (for NYCDEP peak control) • Forest/Open • Same area and soil characteristics • Calculated runoff volume using TR-20/TR-55 for each WQv sizing method design storm

  40. Wet Pond Impervious Pervious

  41. Wet Pond Impervious Pervious

  42. Design Standard

  43. Purpose • To address design standards in phosphorus-limited watersheds • EOH NYC Water Supplies Watersheds • Greenwood Lake • Onondaga Lake • Provide consistency with NYCDEP watershed rules and regulations • Enhance Criteria consistent with the existing State standards

  44. Enhanced Phosphorus Removal Standards • A measurable, significant improvement in phosphorus treatment performance over the current Standards. • How much stormwater is prevented? • How much of the remaining stormwater is treated? • What is the effluent quality of the treated runoff? • Based on • Modeling hydraulics and theoretical studies • Empirical and performance of practices

  45. Recommendation • 1 year-24 hour Sizing Method estimated to achieve > 80% treatment for both storage and flow through systems. • Decreasing marginal gain in treatment performance as WQv size increases • Results in • Alternative that modifies WQv sizing • Use of TR-55/TR-20 methods • Incorporate physical characteristics of the site

  46. Performance Goals: source control Goal 1 - Reduce runoff volumes to the maximum extent practicable • Hydrologic Source Control • Evapotranspiration • Infiltration • Infiltration Requirement • Infiltration credit • Incorporate soil in sizing • Site evaluation

  47. Performance Goals: source control • Evaluation Requirements • Imp. area disconnection • BSD / LID / Green infrastructure • Standard Infiltration

  48. Performance Goals: source control • Post Construction • Increased Curve Number • Soil De-compaction

  49. Performance Goals: sizing criteria • Goal 2 - Achieve less than 15% effective treatment bypass of the long term runoff volume. • Focus on hydraulic control • Capture and treatment • Bypass • Simulated hydraulic function in SWMM • Applied design in TR-55, TR-20

  50. Sizing Criteria

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