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366318Metropolitan St. Louis Sewer District 2350 Market Street St. Louis, MO 63103-2555 (314) 768-6200 June 30, 2010 Mr. Mark Miller AquaShield 2705 Kanasita Dr. Chattanooga, TN. 37343 RE: Aqua -Filter Stoiinwater Treatment System: St. Louis MSD Submission Redevelopment Use Level (RUL) + Provisional Use Level (PUL) Approval within District Dear Mr. Miller: The Metropolitan St. Louis Sewer District (MSD) has reviewed your application regarding the Aqua - Filter Stormwater Filtration System for use as a Best Management Practice for stotniwater management. MSD is pleased to provide Redevelopment Use Level (RUL) + Provisional Use Level (PUL) approval for use of the Aqua -Filter as a stand-alone water quality BMP, subject to the following provisions. • The Aqua -Filter is approved for use on redevelopment sites of any size. This approval is based on compliance with requirements listed in MSD's Proprietary Water Quality Products and the MSD's Stoiniwater Management Program (Rev. Jan. 2009). Proprietary devices should be treated as a supplementary (rather than a primary) means of meeting small MS 4 requirements. • Proposed uses and designs of the device must be in general conformance with the information and methodologies provided, AquaShield's application dated July 16, 2008 and supplemental information received on March 3, April 3, September 8, 2009 and April 5, 2010. • The use of buried filters shall be avoided on residential type projects. • Aqua -Filter must be sized to capture all floatable trash and free oil, and removes 80% of total suspended solids (TSS) for the site water quality Volume (WQ„). Procedures for calculating WQ„ are provided in Volume I of the Maryland Stoiniwater Design Manual (2000). All units shall be installed with adequate storage to treat 75% of the WQ,,. (see attached figure) • The peak inflow is limited to 0.27 cfs (10gpm/ft2) for each filtration row. Each row of filter is limited to a maximum contributing drainage area of 0.5 acres for each filtration row. Cartridges shall use a perlite media. • The device must be configured so that the weir wall is removable and extended to the ceiling of the structure. All units including pretreatment, should be configured in an off-line layout. • Adequate pretreatment shall be provided in all site designs, in this case this will likely include an Aqua -Swirl unit. No reduction in the number of filters shall be made for the installation of pretreatment. The Aqua -Swirl shall be sized to remove 50% of the TSS (OK 110 PSD) water quality flowrate (WQf). • All proprietary lids and covers should be captive components. At least one "oversized" access placed over the filters shall be proved on the filter vault and another access shall be placed over the storage chamber. The Neenah Model R-1741-F-1, cover, or equivalent, MSD approved cover is required. Project specific design calculations and maintenance plans furnished by AquaShield must be included within the project's "Stormwater Management Facilities Report" prepared by the consulting engineer. The devices maintenance plan shall be consistent with the plans presented in the AquaShield Product System Maintenance Catalog. The initial installation of the Aqua -Filter in the MSD shall include the following: 1) A manufacturer's or vendor's representative must be onsite during the proprietary BMP installation to ensure the product's installation requirements are met. 2) Shop drawings indicating elevations of flowlines, weirs, pipe inverts, etc. will be required prior to installation. 3) The manufacturer or vendor must arrange for an as -built survey of the proprietary BMP to be perfoiiiied by a Missouri -registered Professional Land Surveyor once the device has been installed, and prior to any testing or monitoring. 4) Upon construction approval of the initial installation of this device the manufacturer shall prepare and submit a QAPP (Quality Assurance Performance Plan) to the BMP committee for review. At a minimum the QAPP shall address: include 4a and 4b as bullets. 4a)The manufacturer or vendor must perfoini quarterly inspections of the proprietary BMP during its' first year of operation, which will include visual inspections and quantitative analysis of the service's sediment removal efficiency, especially as compared to its design efficiency. MSD requests to be invited to these inspections to further enhance familiarity and understanding of the device. 4b)Formal reports shall be submitted to MSD, including as-builts and at each quarterly inspection. The reports shall include summaries, quantitative analysis mentioned in item 4, photographs of the stricture, inlet, internal conditions of the structure, the filters, and outfall conditions, etc. The reports shall also evaluate the performance of the owner's adherence to the approved maintenance program, and offer suggestions for any areas of improvement. 5) Upon approval of the QAPP, the manufacturer shall carry out the plan. MSD reserves the ability to withdraw or modify this approval based on subsequent information, including information indicating that this BMP does not satisfy MSD piles, requirements, or construction specifications. Sincerely, roc,ciad T Bbackile/is' Michael T. Buechter, P.E. Principal Engineer (BMP Committee Chairman) Engineering/Design Metropolitan St. Louis Sewer District