5.4. SR 05-02-2005 - Laserfiche WebLink

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East Elk River Elemenuuy School/CU 05-08 Apri121, 2005 Page 2 · A bigger issue with the drainage plan is Sedimentation Pond # 1 is not located on the School District's proposed property. It is located north of the River Park north plat line. In fact, it actually crosses the existing County Road 40. Additionally, the outlet from Sedimentation Pond #2 crosses the proposed new County Road 40 and outlets into a proposed pond for part of the River Park development which will not be construction in Phase 1. This causes an issue of timing and may require additional outlet pipe to be constructed, if the pond on the east side of County Road 40 is not complete at the time that the School District needs to provide the outlet. · There is also a concern from the Technical Evaluation Panel that the existing. wetland on the east side of the School District property that is being maintained not be deprived of hydrology. We would recommend then that the outlet from Sedimentation Pond #2 be routed through the existing wetland immediately to the southeast before crossing County Road 40 and ultimately outletting. · The plans should show a detail of the outlet structure from each of the ponding areas. B. Sheet Ct.4 · The grading near the northwest driveway ILot 13 needs to be coordinated with the River Park grading plan. The slope proposed on the School District property appears to be difficult to blend into the residential lot. · The grading plan needs to include emergency overflow locations and elevations. They should be labeled on the grading plan as emergency overflows with the minimum elevation to be maintained noted. · The slopes shown on Sedimentation Pond #2 are labeled as 4:1 but appear to be drawn at 3: 1. · The plan calls for a 20-foot wetland setback. The proposed new City ordinance which has not yet been adopted by the City Council calls for a larger wetland setback. · The 3:1 slope directly behind the curb in the area of the service dock will be difficult to maintain. A minimum of three feet of relatively flat boulevard area should be shown. · The low area in the courtyard area directly south of the school is shown to have a storm inlet at 34.6. Building Code requires yard grades outside the structure to be a minimum of six inches below the first floor elevation. Additionally, a first floor elevation adjacent to a low area drained by storm sewer needs to be one foot above the emergency overflow elevation out of the low area. This general area of grading and the storm sewer inlet elevation need to be reviewed to ensure that proper separations and emergency overflows are maintained. S:\PLANNING\Case Files\2005\CU 05-08 Anderson-Johnson\04 2105 engrs memo.doc