02-14-1994 Council Packet - Laserfiche WebLink

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Request for Council Action contimicd page 3 of 6 Fcbniary 10. 1994 Zoning File #1862 problem at the southeast comer where drainage runs into Lot 13 and ponds. TlKre are no drainage ditches along the north side of Watertown Road. As with the earlier 3 lot subdivision review, the normal drainage and utility easement widths would be expanded from 10' to 35' along the east to allow for the installation of berms that would control and carry runoff to the northeast detention pond. Note drainage exits at the northeast via an existing drainage ditch. Drainage would no longer haphazardly drain through rear yards of esublished neighborhood to east. Review Exhibits R-1 and V, note that the drainage swale along the east property line has been lowered by extending the 1022 contour 50’ to the south and providing a 1021 elevation at the southeast property comer to allow for a 5.5% grade within the ditch. This will keep the ditch lower than Lots 12 and 13 in the Daniels Long Lake Heights Addition. Gusufson also notes the need to lower ditches adjacent to the private road and Watertown Road at least 2 1/2' below the elevation of the centerline street grade. Gustafson advises that the septic site on Lot 7 shown at an elevation of 1027 must be protected by requiring that the existing pond on Lot 8 be maintained at a high water level of 1024 with an outlet ditch at 1023.5 to set normal water level. Applicant has commenced the permitting process with the Minnehaha Creek Watershed District, that continues to function as the LGU or local govemmenul unit responsible for implementing directives of the Boaru of Water & Soil Resources and the 1991 Wetland Conversation Act. review Exhibit K. The Watershed District will issue a permit as soon as applicant has provided design of emergency overflow at the northeast pond and an analysis of downstream capacity. The Watershed District's permit will also condition approval on the first floor level elevation of the future home on Lot 4 being placed at either 1014.5 or 2' above the emergency overflow elevation of the northeast pond whichever is highest. Both staff and the Watershed District are concerned with the issue of downstream drainage, specifically the impact of increased runoff on drainage ditch within Lots 2 and 3 of Daniels Long Lake Heights. Staff and developer met with the property owner who has agreed to allow the regrading and lowering of the ditch. With the lowering of the ditch the surveyor has been able to deepen detention pond for greater storage and relocate completely out of treed area. Please review Exhibit U, Gustafson s final review comments on revised grading plan. Staff asked Peter Fossen. the owner of the property, if he would consider granting an easement to the City but he refused. Any unregulated alteration of this ditch would have a major impact on the storm water controls within the subdivision. Staff recommends that the developer obtain a drainage easement from Fossen. The easement would forewarn any future owner of its importance. Any attempt to block drainage in future can be remedied by either homeowners association or City having authority to enter property to correct blockage.