Minutes - Public Works Committee - 10/21/2003

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drainage area to this wetland depression from 12.43 acres to 4.01 acres, although it also increased the contributing impervious area by adding half of the roof areas from seventeen additional singe family units. A review of drainage submittals show the net effect of the basin modifications by the development of Village of Sunfish Lake is a reduction in runoff from a 100-year precipitation event from 0.676 acre-feet to 0.296 acre-feet. A new outlet was also provided from this depression at an elevation of 863.0. A precipitation event, which consists of back-to-back 100- year storms, would cause the water level in this wetland to rise to a maximum elevation of 863.6. Residents located at 14660 and 14680 Potassium Street expressed concern over the drainage change, noting that this summer the low portions of their backyard appear wetter than in the past, despite the dry spell beginning in early July. A meeting was held with the residents on Friday, October 17, 2003 on site with the residents, the developer and his engineer, and the City engineering department. The location of the 863.0 and 863.6 contours had been surveyed and staked as well as the drainage and utility easement in these yards. These contours were contained entirely within the drainage and utility easement on the Mault's property (14660), but fell outside the easement limits of Roofs property (14680) in places up to approximately ten feet. Although the 10-year water conditions are either wholly or substantially contained within existing easements, it is felt some cooperative arrangement should be considered to alleviate resident concerns. Staff is therefore recommending that following possible measure be considered to achieve this goal. (1) The City/Developer delineate the wetland boundary through these rear yards. Such that yards may be filled in compliance with the wetland regulation. (2) The City/Developer deliver fill material to these yards to enable the residents to raise portions of their yards outside the delineated wetland. and/or (3) The City/Developer purchase additional easement for the area of the Roofs near yards. Staff recommended against lowering the new outlet piper for two reasons. First, flattening the pipe grade will impair the efficient removal of ponded water. Also, substantial portions of these two yards would still be inundated in areas under extreme conditions, and lowering the pipe outlet would not change this. Staff also discussed the possibility that the wet conditions may be occurring due to the dewatering activities that have taken place in the City since September. Tamara Mault, 14660 Potassium Street NW, Ramsey, stated that her main concern was that she wanted to make sure that they did not lose their trees that have been growing there for 20 years. A letter was presented to the Committee from Tamara and Jay Mault expressing their concerns. Councilmember Kurak inquired if there was any piping from their yards that lead into the wetland area, such a pipes for a sprinkling system. Ms. Mault replied no. Public Works Committee/October 21, 2003 Page 2 of 8