NYSOGS/NYSDEC Stormwater Management Design Manual

Writing the Book on Stormwater in New York State

As part of LaBella’s Environmental Term Contract with New York State Office of General Services, LaBella worked with the New York State Department of Environmental Conservation (NYSDEC) to perform a comprehensive revision to the New York State Stormwater Management Design Manual (SWDM). The SWDM defines technical requirements for the design of stormwater management practices (SMPs) on projects that require coverage under the NYSDEC State Pollutant Discharge Elimination System (SPDES) General Permit for Stormwater Discharges from Construction Activity. Design engineers are required to refer to and conform to this statewide reference.

The multi-step revisions were closely collaborated with the NYSDEC central office, and staff from Regions 4 and 8, with input from other stakeholders including NYS Environmental Facilities Corporation (EFC), New York City Department of Environment Protection (DEP), NYS Department of Transportation (DOT), the NYC Watershed Inspector General, and the Center for Watershed Protection (CWP).

The Review

The initial phase included a full review of the 2015 manual, in comparison to stormwater references from other states and agencies that were identified by the NYSDEC. This analysis helped identify existing SMPs to receive minor or major revisions, as well as SMPs to be removed or added.

LaBella then began rewriting the design and performance criteria for each practice, with the goal of eliminating design guidance and focusing on design requirements. Research was conducted to ensure that design criteria and material specifications were updated for the latest technologies, technical studies of installed SMP functionality, and construction/maintenance data.

The Revisions

The draft manual was released to NYSDEC in May 2022 for a public comment period that concluded in December 2022. At the conclusion of the public comment period, LaBella revised the manual to address and incorporate public comments. The final SWDM was released in July 2024.

The comprehensive revisions included:

Updated technical requirements for SMPs;
Enhanced guidance for removal of pollutants of concern, redevelopment activities, stormwater hotspots, and infiltration practices;
Addition of new SMPs;
New chapters for design examples, application of SMPs in urban areas, and planting guidance for SMPs;
Incorporation of the DEC Maintenance Guidance as a new chapter;
Updated Appendix D for soil test requirements;
General clarifications and reformatting to improve user experience and ensure consistent application of the technical requirements;
Creation of AutoCAD details for each SMP, available for download on the NYSDEC website;
Updated inspection checklists; and
Updated calculation worksheets for the 6-Step Process for Stormwater Management Planning/Practice Selection, as well as each individual SMP.