Resource Directory

PWD’s Stormwater Regulations require that 100% of runoff that cannot infiltrate into the ground be routed through an acceptable pollutant-reducing practice. Filter products reduce pollutant levels by removing sediments, metals, hydrocarbons, and other pollutants from stormwater. PWD requires that filter products reduce the effluent event mean concentration of total suspended solids (TSS) to 15 mg/L or below. Filters must be evaluated on a project-specific basis since site conditions, such as sediment loading and/or drainage area size, can impact a device’s ability to meet PWD’s Stormwater Regulations.

All proprietary practices proposed for use on a project must be evaluated and accepted for removal efficiency using the standards of the following stormwater management practice evaluation systems: the State of Washington Technology Assessment Protocol – Ecology (TAPE), or the New Jersey Corporation for Advanced Technology (NJCAT). PWD will also accept third-party testing and documentation, if available, that proves that the product can meet this requirement. PWD has reviewed these sources and included products that are able to meet these requirements in the Reviewed Media Filter Products table.

Low Flow Devices

PWD’s Stormwater Regulations require that 100% of the runoff that cannot infiltrate into the ground in a combined sewer area must be released from the site at a maximum of 0.05 cubic feet per second (cfs) per acre of associated DCIA.  PWD requires that low flow devices, or proprietary rate control products, meet this peak release rate requirement.  Rate control products will be evaluated based on engineering specifications, specifically the rate curves provided by the manufacturers of such products.  PWD will also accept third-party testing and documentation, if available, that proves that the product can meet this requirement.  Products that have been reviewed by PWD are listed in the Reviewed Low Flow Devices table.