12728 19TH AVE SE BASE FILE 2025-07-29

Description The Stormwater Management StormFilter@(StormFilter) is a passive, flow-through, stormwater filtration system that is installed inline with storm drains. The system is comprised of one or more vaults that house rechargeable, media-filled, filter cartridges. The StormFilter works by passing stormwater through the media-filled cartridges,which trap particulates and adsorb materials such as • dissolved metals and hydrocarbons.Once filtered through the media, the treated stormwater is directed to a collection pipe or discharged into an open channel drainage way. The StormFilter is offered in four different configurations:cast-in-place, precast, linear, and catch basin.The precast, linear, and catch basin models utilize pre-manufactured units to ease the design and installation processes.The cast-in-place units are customized for larger flows and may be either covered or uncovered underground units. Purpose The StormFilter is a passive,flow-through, stormwater filtration system designed to improve the quality of stormwater runoff from the urban environment before it enters receiving waterways. It is intended to function as a Best Management Practice(BMP) to meet federal, state, and local requirements for treating runoff in compliance with the Clean Water Act. Through independent third party studies, it has been demonstrated that the StormFilter is highly effective for treatment of first flush flows and for treatment of flow-paced flows during the latter part of a storm. In general, the StormFilter's efficiency is highest when pollutant concentrations are highest. The primary non-point source pollutants targeted for removal by the StormFilter are: sediments. (TSS), oil and grease, soluble metals, nutrients, organics, and trash and debris. • Sizing The StormFilter is sized to treat.the peak flow of a water quality design storm. The peak flow is determined from calculations based on the contributing watershed hydrology and from a design storm magnitude set by the local stormwater management agency. The particular size of a StormFilter unit is determined by the number of filter cartridges(see Figure 1) required to treat this peak flow. The flow rate through each filter cartridge is adjustable, allowing control over the amount of contact time between the influent and the filter media. The maximum flow rate through each cartridge can be adjusted to between 5 and 15 gpm using a calibrated restrictor disc at the base of each filter cartridge. Adjustments to the cartridge flow rate will affect the number of cartridges required to treat the peak flow. Basic Function • The StormFilter is designed to siphon stormwater runoff through a filter cartridge containing media. A variety of filter media is available and can be customized.for each site to target and remove the desired levels of sediments, dissolved phosphorus, dissolved metals, organics, and oil and grease. In many cases, a combination of media is recommended to maximize the effectiveness of the stormwater pollutant removal.