Agenda - Council - 09/23/1997 - Laserfiche WebLink

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o o when the ordinance was established in 1987. The City Engineer contacted the Department of Natural Resources, the Anoka Soil and Water Conservation District and the Board of Soil and Water Resources and found no knowledge of such a model ordinance containing such a provision and in fact, the Anoka Conservation District and DNR encourage the construction of ponds under certain conditoins. In summary, I cannot provide a reason for this provision in our existing code. A second aspect relating to this issue was raised by public comment concerning how the creation of the pond may affect surrounding hydrology, particularly adjacent wetlands. Although no soil borings or geologic analysis has been performed, based on the general geology of the area and generalized soil maps, it is my opinion that this pond Will have little if any' impact on the local hydrology. I base this conclusion on the fact that the groundwater system contains a vastly larger volume than that which will be created by the excavation. The Lower Rum River Water Management Organization engineer and the Anoka Conservation Service Manager conceurred with my opinion. The DNR area hydrologist acknowledged that my conclusion could be true but was reluctant to categorically concur. He noted a case in Ham Lake where construction of a lake has caused concerns relating to lowered groundwater levels. The DNR is currently studying this case. The protection of the County ditch from sedimentation is an area of concern. Staff proposes a 30 foot undisturbed buffer between the ditch and the proposed silt fence. The dispos'aI of brush resulting from the clearing and grubbing associated with this operation is of concern. Tree trunks will be salvaged for firewood. Limbs and brush will be consolidated in piles surrounding the pond excavation where it will be left to decompose. Staff is recommending covering brush piles with excavated material to hasten decomposition and reduce the risk of fire hazard. The proposed pond will extend, primarily on the north into an area which is shown to be at an elevation of 900, which is eight feet higher than the ditch elevation. Proposed grades along the edge have not been specified. Staff is recommending that the transition between existing grades and the proposed lake shall be a uniform grade consistent with the maximum grade allowed in the City ordinances. Topsoil stockpiles are identified (but not labeled) on Exhibit A surrounding the proposed lake. Staff is recommending that a maximum height of 25 feet be established as proposed in the application submittals. Staffis recommending that only State and County highways be allowed for the transport of excavated material from the property. The proposal submittals suggest that excavated material may be placed temporarily or permanently within areas that may be classified as wetlands. The terms of this permit should be made to clearly identify that a permit may be required from the Lower Rum I I I I I I I I I: I I I I I I I I I I