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Howard R. Green Oompany <br /> <br />March 17, 2004 <br />File: 823320J-0240 <br /> <br />Ms. Michele McPherson <br />Director of Planning <br />City of Elk River <br />13065 Orono Parkway <br />Elk River, MN 55330 <br /> <br />RE: SHERBURNE COUNTY JUSTICE CENTER EXPANSION <br /> <br />Dear Ms. McPherson: <br /> <br />As requested, we have reviewed the site civil portion of the Sherburne County Justice Center <br />expansion. The plans we reviewed were prepared by Loucks and Associates and were marked as <br />95 percent complete with a date of January 23, 2004. Based on our review and comments <br />received at the staff review meeting, we would offer the following comments: <br /> <br />A. Storm SewerlPonding <br /> <br />1. The existing storm drainage pond located in the southwest corner of the site is <br /> proposed to be reshaped and moved slightly further west. In this move of the pond, <br /> the proposed side slopes are proposed to be steepened from a 4:1 to a 3:1. Best <br /> Management Practices, which the City has adopted and follows, requires that the <br /> side slopes remain at a 4:1 slope. In addition, no drainage calculations have been <br /> provided to determine first of all if the same capacity is provided in the reconfigured <br /> pond, and secondly, if additional storage volume has been added for the additional <br /> impervious area caused by this Justice Center expansion. <br />2. Much of the existing storm sewer system is being abandoned and removed to make <br /> way for the Justice Center expansion. The revised storm sewer system is now <br /> extended down the roadway on the east side of building around the south side of <br /> the building and into the pond. The City has a 40-foot drainage and utility easement <br /> along the east side and south side of the property. Within that easement is <br /> contained trunk sanitary sewer and watermain. The sanitary sewer is approximately <br /> 18 feet deep. The new storm sewer placed on the east side of the road on the east <br /> side of the building is within five feet of the sanitary sewer. We would recommend <br /> that the storm sewer line be placed on the west side of the roadway to provide more <br /> separation from the existing sanitary sewer. <br />3. There will be three new outlets into the reconfigured drainage pond. There is a <br /> standard plate showing riprap at the outlet of these pipes. In addition, there should <br /> be a Storm Water Pollution Prevention Plan (SWPPP) submitted with the project, <br /> which would detail all of the sediment and erosion control along with turf <br /> establishment requirements for the project. As you are aware, the City is in the <br /> <br />Ltr-031704-McPherson.doc <br /> <br />2550 University Avenue West · Suite 400N · St. Paul, MN 55114 · 651/644-4389 fax 651/644-9446 toll free 888/368-4389 <br /> <br /> <br />