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HomeMy Public PortalAboutChambermax PUL 1-26-18 1 January 26, 2018 Mr. Joe Bratchie CONTECH Engineered Solutions, LLC 8133 Whitburn Dr. Apt. C Clayton, MO 63105 RE: ChamberMaxx Provisional Use Level (PUL) Approval within the District Dear Mr. Bratchie: MSD has reviewed your application regarding use of the ChamberMaxx System. MSD is pleased to provide the chambers PUL approval for use as a stormwater storage system. • The ChamberMaxx System may be used to provide storage for peak flood detention (Qp), channel protection (CPv), or water quality (WQv) design storm volumes. Where the ChamberMaxx System is provided for storage of WQv, geotextile liner shall be provided on the interior bottom and sides of the chambers, and shall meet or exceed MSD Standard Construction Specifications for Geotextile Fabric. • The ChamberMaxx System on its own is not intended to be a device that is used as a standalone water quality BMP. Where the ChamberMaxx System is used within a water quality strategy (e.g., as water quality storage in conjunction with filtering BMPs), then adequate pre-treatment such as a sediment containment row shall be provided upstream of the storage. • The ChamberMaxx System may be used as part of an infiltration system, subject to MSD design requirements for infiltration systems. • Consistent with MSD Rules and Regulations, the use of buried storage shall be avoided on residential type projects. • The ChamberMaxx System should be kept off-line until the construction site is stabilized and otherwise protected from sediment build-up during and after construction. • Adequate access and inspection access shall be provided. • Any proprietary lids and covers should be captive components. • Project specific design calculations and maintenance plans furnished by CONTECH shall be included within the project’s “Stormwater Management Facilities Report” prepared by the consulting engineer. All applicable elements of the design shall comply with the ChamberMaxx System 2017 product submittals. Please also note the following: 1) Prior to MSD approval of any development plans, the product maintenance plan will be updated to address any remediation procedures needed to repair the system should it be damaged. 2) Site specific construction details are required for each project. MSD is providing this product approval letter with the condition that all engineering details needed for subsequent shop drawing and construction approval will be developed prior to MSD approval of engineering plans. Please advise any potential customers 2 of this, as this could potentially impact their project’s design and construction schedule. • The initial design and installation of the ChamberMaxx System in the MSD shall include the following: 1) Sealed engineering documents by a professional engineer licensed in Missouri. 2) Construction supervision by CONTECH, to ensure the product’s installation requirements are met. 3) Shop drawings indicating elevations of flowlines, pipe inverts, etc. prior to installation. 4) An as-built survey, arranged by the manufacturer or vendor, of the proprietary storage device to be performed by a Missouri-registered Professional Land Surveyor once the device has been installed, and prior to any testing or monitoring. 5) Quarterly visual inspections of the proprietary device during its’ first year of operation, performed by you or your representative. MSD requests to be invited to these inspections to further enhance familiarity and understanding of the device. 6) Formal reports shall be submitted to MSD, including as-builts and at each quarterly inspection. The reports shall include a summary description and photographs of the structure, inlet, internal conditions of the structure, and outfall conditions, etc. The reports shall include evaluating 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 information indicating that this BMP does not satisfy MSD rules, requirements, or construction specifications. Sincerely, Jason Peterein, P.E. Principal Engineer (Proprietary BMP Committee Chair) Engineering/Planning-Development Review