Agenda - Council - 04/26/2016 - Laserfiche WebLink

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separation is provided between the lowest elevation of an area to be used for infiltration and bottom of the boring where groundwater was not encountered — 3 foot of separation is required. To meet the LRRWMO water quality requirements to provide a 60% annual removal efficiency for phosphorus and 90% annual removal efficiency for total suspended solids a minimum "dead -storage" volume of 1,035 cubic feet is required from the entire 4.1 acre site. A volume of 11,434 cubic feet is to be provided within the two proposed basins. The construction plans shows that the finished garage floor elevations (lowest floor) of the townhomes range from 857.0 M.S.L. to 858 M.S.L. The calculated 100-year frequency flood elevation of the eastern basin is 855.5 M.S.L. The surface overflow from the eastern basin is elevation 856 M.S.L, providing one (1) foot of separation complying with LRRWMO criteria for the separation between the low floor elevation and the surface overflow elevation of a basin. The construction plans shows that the finished floor elevation of the consulting center is to be 858.2 M.S.L. The calculated 100-year frequency flood elevation of the western basin is 856.2 M.S.L., providing 2 feet of separation Silt fence is shown to be installed at the limits of construction with a gravel construction entrance. It is our recommendation that the LRRWMO approve of the permit for this project subject to the following conditions: 1. Erosion control measures need to be installed prior to the commencement of construction. 2. Upon completion of construction and restoration of disturbed areas, the permit applicant is responsible for the removal of all erosion control measures installed throughout the construction site. 3. To minimize the potential of material from leaving the site and being tracked onto the roadway, a rock filter dike being a minimum of two feet in height and having side slopes of 4:1 must be constructed at the entryway onto the site. The rock filter dike will provide an erosion control facility and also enable construction traffic to enter the site. 4. Street sweeping must be undertaken and completed on an as needed basis. 5. Compliance with the stone water management requirements of the Lower Rum River Watershed Management Organization are to be administered for this project by the City of Anoka. 6. In all cases where the doing by the permittee of anything authorized by this permit shall involve the taking, using, or damaging of any property, rights or interests of any other person or persons, or of any publicly owned lands or improvements or interests, the permittee; before proceeding; shall obtain the written consent of all persons, agencies, or authorities concerned, and shall acquire all necessary property rights and interest. P:1Mpls\23 MN102123020471WorkFiles4LR1 WM0 PermitMemos12016Vrr1602.docx