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366314Metropolitan St. Louis Sewer District 2350 Market Street St. Louis, MO 63103-2555 (314) 768-6200 August 3, 2010 Mr. John MacKinnon, P.E. Regulatory Specialist Hydro International 94 Hutchins Drive Portland, ME 04102 : Reg-U-Flo0 Vortex Flow Control Valve Provisional Use Level (PUL) Approval within District Dear Sir: The Metropolitan St. Louis Sewer District (MSD) has reviewed your application regarding the Reg-U-Flo0 Vortex Flow Control Valve for use as a stoimwater flow control device. MSD is pleased to provide Provisional Use Level (PUL) approval for the Reg-U-Flo® Vortex Flow Control Valve for use as a stolinwater flow control device, subject to the following conditions. o The Reg-U-Flow device may be used in flood protection (Qp) and channel protection (Cp) detention basin outlet structures. When used for Cp, routing must show that the 24- hour extended detention is provided. The 24 hour extended detention is defined as providing a 24 hour lag time (T) for the one year 24 hour rain event. "T" is defined as the interval of time between the centroid of the inflow and the centroid of the outflow hydrograph. O Project specific design calculations and maintenance plans furnished by Hydro International must be included within the project's "Stolinwater Management Facilities Report" prepared by the consulting engineer. All applicable elements of the design shall comply with the "Reg-U-Flo® Vortex Flow Control Submittal to Metropolitan St. Louis Sewer District Version 1.0," September 30, 2009. O Project specific design calculations including a stage discharge curve corresponding to each flow control valve provided must be included within the project's "Stoiiiiwater Management Facilities Report" prepared by and sealed by the consulting Professional Engineer licensed in the state of Missouri. O Proper access shall be provided to each location to ensure proper maintenance and inspection of the flow control valve. The minimum size access hole is 30 inches in diameter. All proprietary lids and covers should be captive components. o The manufacturer shall guarantee the Reg-U-Flo0 Vortex Flow Control Valve to be free from defects in materials and workmanship for a period of twelve months following MSD construction approval. • Flow control valves shall be protected from sediment build-up during and after construction. A trash rack will be required for orifices 8 inches and smaller. • The initial installation of the Reg-U-Flo® Vortex Flow Control Valve in the MSD shall include the following: 1) A manufacturer's or vendor's representative must be onsite during the installation to ensure the product's installation requirements are met. 2) Shop drawings indicating elevations of flowlines, pipe inverts, etc. will be required prior to installation. 3) The manufacturer or vendor must arrange for an as -built survey of the proprietary device 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 device 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) Foiinal 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, 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. MSD reserves the ability to withdraw or modify this approval based on subsequent information, including infoiiiiation indicating that this BMP does not satisfy MSD rules, requirements, or construction specifications. Sincerely, 1 r��T�_ 73 Michael T. Buechter, P.E. Principal Engineer (BMP Committee Chairman) Engineering/Design Metropolitan St. Louis Sewer District