2600 FEDERAL AVE 2021 PORT OF EVERETT 2025-09-29

• Indications of the need for maintenance include effluent flow decreasing to below the design flow rate, as indicated by the scumline above the shoulder of the cartridge. • Owners/operators must inspect StormFilter with ZPG media for a minimum of twelve months from the start of post-construction operation to determine site-specific maintenance schedules and requirements. You must conduct inspections monthly during the wet season, and every other month during the dry season. (According to the SWMMWW, the wet season in western Washington is October 1 to April 30.According to SWMMEW, the wet season in eastern Washington is October 1 to June 30).After the first year of operation, owners/operators must conduct inspections based on the findings during the first year of inspections. • Conduct inspections by qualified personnel, follow manufacturer's guidelines, and use methods capable of determining either a decrease in treated effluent flowrate and/or a decrease in pollutant removal ability. • When inspections are performed, the following findings typically serve as maintenance triggers: • Accumulated vault sediment depths exceed an average of 2 inches, or • Accumulated sediment depths on the tops of the cartridges exceed an average of 0.5 inches, or • Standing water remains in the vault between rain events, or • Bypass occurs during storms smaller than the design storm. • Note: If excessive floatables (trash and debris) are present,perform a minor maintenance consisting of gross solids removal, not cartridge replacement. 6. CONTECH shall maintain readily available reports listed under "Application Documents" (above) as public, as well as the documentation submitted with its previous conditional use designation application. CONTECH shall provide links to this information from its corporate website, and make this information available upon request, at no cost and in a timely manner. 7. ZPGTM media used shall conform with the following specifications: • Each cartridge contains a total of approximately 2.6 cubic feet of media. The ZPGTm cartridge consists of an outer layer of perlite that is approximately 1.3 cubic feet in volume and an inner layer, consisting of a mixture of 90% zeolite and 10% granular activated carbon,which is approximately 1.3 cubic feet in volume. • Perlite Media: Perlite media shall be made of natural siliceous volcanic rock free of any debris or foreign matter. The expanded perlite shall CONTECH-StormFilter®GULD Maintenance Update(November 2012) Page 13