2320 RAILWAY AVE INTERWEST CONSTRUCTION INC 2023-02-02

I INTERWEST—EVERETT CONTRACTOR'S YARD SITE IMPROVEMENTS Sitts & Hill Engineers, Inc. OPERATION AND MAINTENANCE MANUAL Job Number 18,831 I Maintenance Guidelines In addition to these two activities,a is important to check The primary purpose of the stormwater Management the condition,of the StormFilter unit after major storms for StormFilter"is to filter and prevent pollutants from entering our potential damage caused by nigh flows and for high sediment accumulation that may be caused by localized erosion in the waterways. I ike any effective filtration system,periodically theseI drainage area. It may be necessary to adjust the inspectioN pollutants must be removed to restore the StormFilter to its full maintenance schedule depending on the actual operating efficiency and effectiveness. conditions encountered by the system.In general,inspection Maintenance requirements and frequency are dependent on the activities can be conducted at any time,and maintenance should I pollutant load characteristics of each site. Maintenance activities occur,if warranted,during dr+rrr months in late summer to early may be required in the event of a chemical spill or due to 'al excessive sediment loading from site erosion or extreme storms.It is a good practice to inspect the system after major storm events. Maintenance Frequency The primary factor for determining frequency of maintenance for Maintenance Procedures the StormFilter is sediment loading. Although there are many effective maintenance options,we A properly functioning system will remove solids from water by believe the following procedure to be efficient,using common trapping particulates in the porous structure of the filter media I equipment and existing maintenance protocols The following inside the cartridges.The flow through the system will naturally two-step procedure is recommended:: decrease as more and more particulates are trapped.Eventually 1.Inspection the flow through the cartridges will be low enough to require • Inspection of the vault interior to determine the need for replacement It may be possible to extend the usable span of the maintenance. cartridges by removing sediment from upstream trapping devices 2.Maintenance on a routine as-needed basis,in order to prevent matenal trom being re-suspended and discharged to the StormFilter treatment • Cartridge replacement system • Sediment removal Inspection and Maintenance Timing The average maintenance lrfecycle is approximately 1-5 years. Site conditions greatly influence maintenance requirements. At least one scheduled inspection should take place per year with StormFilter units located in areas with erosion or active I maintenance following as warranted_ construction may reed to be inspected and maintained more often than those with fully stabilized surface conditions. First,an inspection should be done before the winter season. During the inspection the need for maintenance should be Regulatory requirements or a chemical spill can shift maintenance determined and,if disposal during maintenance will be required, timing as well.The maintenance frequency may be adjusted as samples of the accumulated sediments and media should be additional monitoring information becomes available during the obtained. inspection program.Areas thatt develop known problems should be inspected more frequently than areas that demonstrate no Second,if warranted,a maintenance(replacement of the filter problems,particularly after major storms. Ultimately,inspection cartridges and removal of accumulated sediments)should be and maintenance activities should be scheduled based on the I performed during periods of dry weather.cartridges records and characteristics of an individual StormFilter system or site.It is recommended that the site owner develop a database to properly manage StormFilter•nspection and 1 maintenance programs.. Ifit ' _ •• 1 _ r _� .. . -.2 r .%... ; T� x- .".`•. .<t... .. ': b .." .••• I SITTS& HILL ENGINEERS, INC. 20 ITACOMA, WASHINGTON