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Stormwater Design Standards

New Stormwater Design Standards

The Stormwater General Construction Permit (SPDES GP-0-15-002) now requires the use of the revised 2015 NYS Stormwater Management Design Manual. All projects for which Notices of Intent were submitted to the New York State Department of Environmental Conservation (NYSDEC) in Albany on and after March 1, 2011 must be designed in accordance with the new standards. For treatment of water quality to remove pollutants, focus has shifted away from large, engineered, “end-of-pipe” stormwater management practices (predominantly retention ponds and infiltration basins) to the use of natural features to manage stormwater runoff near its source. The new process for stormwater management design contains three elements:

  1. AVOID THE IMPACTS - Reduce the amount of stormwater runoff generated by preserving natural features and resources. Preserving natural features and using them as a means of reducing runoff. This may be accomplished by reducing construction footprints, preserving important hydrologic features, locating development in less sensitive areas.
  2. REDUCE THE IMPACTS - Reduce the amount of runoff generated by decreasing impervious surface within the area that is developed. This is done by reducing the street and cul-de-sac widths, sidewalks, parking lot sizes, and building footprints, and incorporating open space into site design.
  3. MANAGE THE IMPACTS - Treat multiple small volumes of runoff near the source using practices designed to mimic natural processes such as soil infiltration, evaporation, and plant uptake (green infrastructure). Examples include pervious pavement, tree planting, rain gardens, bioretention, vegetated swales, stormwater planters, rain barrels, green roofs, and soil restoration.

It is important to bear in mind that some traditional practices may still be needed in order to satisfy the quantity control requirements.  These requirements include  the following:

  • Channel Protection Volume (24-hour detention of the 1-year storm)
  • Overbank Flood Control (Attenuation of the peak flow from the 10-year storm)
  • Extreme Flood Control (Attenuation of the peak flow from the 100-year storm)

As of February 2017, GP-0-15-002 requires the use of the updated New York State Standards and Specifications for Erosion and Sediment Control (Blue Book). The updated Blue Book provides standards and specifications for the selection, design, and implementation of erosion and sediment control practices during development of Erosion and Sediment Control Plans as required by the SPDES General Permit for Stormwater Discharges from Construction Activity.