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• ~. Lower Rum River Watershed Management Organization Andover-Anoka-Coon Rapids-Ramsey 2015 First Avenue; Anoka, MN 55303 To: Lower Rum River Water Management Organization From: Barr Engineering Company Date: March 13, 2007 Re: Revised Permit #2006-28: Pine Prairie: Ramsey We have received revised plans for the Gads Prairie development to be located west of Nowthen Boulevard and north of 145`x' Avenue in Ramsey. The site is 1.65 acres in area and 9single-family lots are proposed. This is the former Gads Prairie development, Permit #2006-10 and review comments were sent to the LRRWMO dated January 16, 2007. An on-site storm water management basin is to be constructed in the northwest corner of the site. This • basin provides water quantity and quality control meeting the LRRWMO criteria. The low floor elevations of the proposed structure riparian to the basin are proposed slab on grade and are shown to be constructed at elevation 888.0 M.S.L., 2.3 feet above the 100-year frequency flood elevation of the basin, as calculated by Hakanson Anderson Associates. If in the future structures are to be constructed on Outlots B-C, the low floor elevation of these structures must be set at a minimum elevation of 887.7 M:S.L., two feet above the calculated flood elevation of the basin. A high point is to be constructed in the southwest corner of the site, at elevation 887.5 M.S.L., the separates the hydraulic connection between the pond and the proposed structures on Lots 1-3. The location of the proposed storm sewer system has been modified from the previous review, January, 2007. The system along the rear of Lots 4-9 provides both inflow and outflow from the basin however the outlet is now shown to connect to an existing system to the south of the site. This outlet configuration will enable the system to drain after storm events. The grading plan shows that a surface emergency overflow is to be provided from the basin and it is recommended that this overflow path be placed within a drainage. and utility easement thereby minimizing the overflow elevation from being modified. At the limits of construction, erosion control measures are shown to minimize the potential of sediment leaving areas altered on the site. It is our recommendation that the LRRWMO approve of the permit for this project subject to the following • conditions: 1. All erosion control measures must be installed at the initial stages of construction and be maintained until all areas altered have been restored. C:\Documents and Settings\sjankowski\Desktop\LRRWM0~2006 Permit memosUn•0628a.doc -4 Z 1 _