#NSWD917 Authorized and Unauthorized Non-Stormwater Discharges

Non-stormwater discharges (NSWDs) are discharges that do not originate from precipitation events. Examples of authorized NSWDs include atmospheric condensates, fire hydrant and sprinkler flushing, fire suppression runoff, groundwater reaching the surface, landscape watering, low conductivity cooling water, safety shower/eye-wash testing and operation, utility vault pumpouts, and water line breaks.

These NSWDs are authorized under the Construction General Permit as long as they meet the following conditions:

  • Must be infeasible to eliminate
  • Comply with BMPs as described in the SWPPP
  • Meet numeric action levels (NALs) for pH and turbidity
  • Do not cause or contribute to a violation of water quality standards

Unauthorized NSWDs are prohibited by the Construction General Permit, and include cooling tower spray, vehicle and hand tool wash water, and sanitary sewer breaks. Sites of all risk levels are required to implement BMPs to prevent nonstormwater discharges. Vehicles and hand tools should be washed offsite, and streets should be cleaned in such a manner to prevent NSWDs entering surface waters or drainage systems. If NSWDs do occur, they must be controlled as much as possible and protected from pollutants.

The Construction General Permit requires that visual inspections of NSWDs be performed quarterly. During these inspections, Scott Environmental will observe drainage areas for the presence of NSWDs and their sources. Any sampling information recorded will be included on the site’s Annual Report to be submitted to the Water Board.