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352283Metropolitan St. Louis Sewer District 2350 Market Street St. Louis, MO 63103-2555 (314) 768-6200 October 17, 2008 Mr. Mark Miller Aqua -Shield 2705 Kanasita Dr. Chattanooga, TN. 37343 RE: Aqua -Shield Stormwater Treatment System: St. Louis MSD Submission Redevelopment Use Level (RUL) Approval within District Dear Sir: The Metropolitan St. Louis Sewer District (MSD) has reviewed your application regarding the Aqua -Swirl® for use as a Best Management Practice for stormwater management. MSD is pleased to provide Redevelopment Use Level (RUL) as a stand-alone water quality BMP, subject to the following provisions. • The Aqua -Swirl° is only approved for redevelopment sites less than 5 acres. This approval is based upon compliance with requirements listed in MSD's Proprietary Water Quality Products and the MSD's Stormwater Management Program (January 2008). • The Aqua -Swirl' must be sized to capture all floatable trash and free oil, and remove 80% of total suspended solids for the OK-1 10 particle size distribution at the site water quality flow -rate (WOO. Procedures for calculating WQr are provided in Appendix D.10 of the Maryland Stormwater Design Manual (2000). Table 1 provides a list of approved models and their respective peak treatment WQr. Aqua -Shields" proprietary sizing program for the Aqua -Swirl® product shall not be used for product selection. Table 1: Summary of Aqua -Swirl® W Aqua -Swirl® Model -- ������ a av •11L{4l. Water Quality Flow Rate: 80% TSS Removal (cfs) AS-4 0.85 AS-5 1.2 AS-6 1,7 AS-7 2.3 AS-8 3.0 AS-9 3.8 AS-l0 4.7 AS-12 6.8 • Devices should be configured as off-line units. • All devices shall provide a minimum sediment storage capacity of 10 ft3. • Confined space entry shall not be a requirement for routine maintenance. No special tools or attachments should be required to provide routine maintenance with a vacuum pumping truck. • All proprietary lids and covers should be captive components. The minimum size access hole is 30 inches in diameter. • Project specific design calculations and maintenance plans furnished by Aqua -Shield® must be included within the project's "Stormwater Management Facilities Report" prepared by the consulting engineer. • A reinforced concrete pad shall be placed over the entire Aqua -Swirl® when subject to H-20 (or greater) traffic loading. The pad shall extend no less than 12 inches beyond the outside diameter of the Aqua -Swirl®. A professional engineer shall provide final approval of the design of the concrete pad and the calculations must be included in the submittal. Traffic rated foundry rims and covers shall be installed such that no contact is made between the HDPE access rider and cast iron frame. • The initial installation of the Aqua -Swirl® 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 performed by a Missouri -registered Professional Land Surveyor once the device has been installed, and prior to any testing or monitoring. 4) The manufacturer or vendor must perform 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. 5) 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 structure, inlet, internal conditions of the structure, the filters, and outfafl 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. The Aqua -Swirl° is not approved for general use at this time. MSD reserves the ability to withdraw or modify this approval based on subsequent information, including information indicating that this BMP does not satisfy MSD rules, requirements, or construction specifications. Sincerely, robtkA T. atteLtiii Michael T. Buechter, P.E. Principal Engineer (BMP Committee Chairman) Engineering/Design Metropolitan St. Louis Sewer District