MS4 Pollution Prevention

The following documents provide guidance for the activities that require PP/GH activities to be implemented, which are based on the NYC MS4 Permit. Contractors are required to submit a certification that they will follow the MS4 Permit requirements prior to beginning the project and a certification at the completion of the project that they followed those requirements.

Effective June 1, 2019, New York City is required to administer the Municipal Separate Storm Sewer System Permit (MS4) for the NYC Department of Environmental Conservation (DEC). The NYC Department of Environmental Protection (DEP) is responsible for administering the permit and collecting all documentation for compliance. All relevant projects are to be reviewed at the start of design to see if they are within the MS4 area. 

The MS4 Construction and Post Construction Fact Sheet provides a quick reference of the history behind the permit and what is required. 

The DEP's Municipal Separate Storm Sewer System webpage has detailed information with links to reference material. It also includes an interactive map of the MS4 drainage area, used to determine if a project is within the permit area. If a project site is near the MS4 area, designers are to submit a water-sewer request form, as the MS4 area is being actively increased and the map may not have been updated. In addition, the Division of School Facilities has created an DOE MS4 Sites list of existing school buildings under their jurisdiction that are within the area.

During the scoping phase, all projects that potentially affect stormwater quality are required to perform a Green Infrastructure Assessment. In addition to new construction and other projects that disturb land, roof replacements and repaving projects also trigger this requirement. The SCA has created a Green Infrastructure Assessment Report templates for both Capacity and CIP projects. In addition, a Green Infrastructure Assessment Flow Chart for determining if green infrastructure (not inclusive of green roofs) is technically feasible can be used by designers to help. This flow chart is based on DEP guidelines and is currently in draft form. The SCA will review the assessment reports and make the determination on implementation.

In addition to the ongoing maintenance requirements of the MS4 Permit by the Department of Education, all contractors must follow the requirements of the MS4 Permit. Besides following Stormwater Pollution Prevention Plans and Sediment and Erosion Control to prevent soils from entering the system, contractors must follow and implement measures to meet the pollution prevention and good housekeeping (PP/GH) requirements of the permit. Chapter 7 of NYC Stormwater Management Plan highlights the items that need to be addressed.  Further, the DEP has created single page guidance documents of typical construction activities that would require PP/GH to be implemented with references to the applicable portions of the permit. These documents can be accessed on the Pollution Prevention/Good Housekeeping page.

With the implementation of the Unified Stormwater Rule, DEP requires a SWPPP for projects over ½ acre or where over 5000 SF of pervious area is being made impervious for both the MS4 area and Combined Sewer Area through their portal, though filing with the state is still only required when over 1 acre. To provide insight into the USWR requirements, AKRF’s Civil Team provided a USWR Training presentation to SCA staff and consultants. DEP has prepared a USWR Case Study to provide designers with guidance in preparing their submission to DEP.