06-10-1997 Council Agenda - Laserfiche WebLink

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STREETS AND STORM SEWER We understand that different site layouts are being considered for this development. Therefore, we will make general comments only: We have concerns about utilizing culverts and ditches instead of storm sewer piping. Culverts and ditches historically require more maintenance. Therefore, we would recommend that all surface water be drained by storm sewer piping. Many critical off street areas have slopes that are significantly less than the standard minimum of 2.0 %. Experience leads us to conclude that slopes this flat lead to nuisance drainage problems. Also, it is unclear where drainage will go from the southern property line. Topographic and contour information should be shown beyond the limits of this development on the grading and drainage plan. The low point in the road will need to have a well defined overflow swale off the street to guide surface water to the wetland during heavy rainfalls. A drainage easement will be required for the pond, and a drainage and utility easement will be required for the storm sewer line off of the City right -of -way. These shall be shown on the plat. We will need to see more information regarding the design of the pond The islands shown on the street at the east and west ends will likely be a maintenance and snow plowing problem for the Public Works Department. Please request the Public Works Director's opinion on this matter. WATERSHED DISTRICT DITCH 7B An existing drainage ditch runs from Desoto to just east of Centerville along the Allen extension. We strongly recommend that this drainage be piped as part of developing this property. It is very much in the City's best interest (as well as in the interests of the future residents of the area) to place this drainage underground. This would prevent the type of problems that have been experienced in the Westwind/Windrow area with Ditch 7A. In preliminary conversations, the owner's engineer has indicated that the owner is willing to do this. Subsequent to eliminating this section of ditch, it may be appropriate for the City to take over ownership and maintenance responsibilities of the piped section. MISCELLANEOUS At some point in the approval process, soil borings shall be submitted to the City for use in evaluating the proposed grading plan, pavement design, pipe bedding and the water table elevation. The owner of this development is reminded that their proposed grading and storm sewer plan should be submitted to the Ramsey - Washington Metro Watershed District for approval. Page 14