10-21-1991 Planning Packet - Laserfiche WebLink

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Zoning File #1691 October 17, 1991 Page 7 accepted the position of the City and applicant. It should also be noted that the former sewer pond has now been restored to its original state of a wetland and for all intents and purposes looks like and acts like a wetland. The fence that surrounds the former pond will be removed upon completion of the subdivision. Review Exhibit L. The MCWD advises that an analysis will be required to determine the elevation of the flood plain also noting that storm water run-off from the developed site cannot be stored at or below the flood plain elevation and must be stored above. Review Exhibit S. The current flood plain map shows the entire area of the sewer pond within the flood plain. Based on the MCWD report storm water run-off from development could be directed to the pond. In preliminary discussions with Mr. Quanbeck, he advised that the flood plain would be probably 12' above the flowline of the creek at 938.5 putting the flood plain at approximately 950.5. This would confirm that the proposed building site within Lot 1, Block 1 is located within a flood plain requiring fill to bring it 1 foot above the flood plain at 951.5. In fact, all building sites must be 1' above the defined flood plain. It will be necessary for the City staff to meet with both applicant and the Watershed District to reach some compromise regarding use of pond for retention purposes. It would also appear that the Minnehaha Creek Watershed District has voiced concern with the discharge of nutrients, specifically high phosphorus levels, into the creek and eventual watershed. Various options have been presented for the applicant's consideration. Certain ones appear most objectionable to the City, specifically the treatment with chemicals. If applicant must provide retention above a flood plain elevation, this may have an impact on the dry buildable area of the proposed 13 lots. In light of the concerns expressed by the Watershed District, staff would ask that you review once again Exhibit J, Steve McComas' report specifically on Page 2 of that report where he reviews the analysis of the soil borings of the former sewer pond. The report notes no problems with sediment contamination and that results are comparable if not better than what is found in some storm water detention basins. It also appears the MPCA does not require any further testing as a result of the proposed residential development and that in his opinion for a typical storm water detention pond or wastewater lagoon that the likelihood of serious sediment contamination is small and no additional sampling is needed at this time. These obvious conflicting views must be resolved before we can proceed with the review. Mr Squire has advised that the MCWD was not sent a copy of McComas' report.