CCP 12-17-2001 - Laserfiche WebLink

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Arden Hills Draft SWMP - 2 'he City should consider amending their ordinances and this requirement to allow for flexibility in .. determining the most cost-effective and beneficial means of treating stormwater runoff. ,., Section 3 - Hydraulic and Water Quality Analysis The existing information should be summarized in a figure that identifies the existing water quality treatment with regard to NURP standards for each subwatershed (see attached example). This figure will allow for identification of water quality, treatment ponds and subwatersheds that will benefit from retrofitting or regional water quality ponding. Identify locations of non-treated discharges to City Lakes and Creeks for future retrofit opportunities. It appears that the City has the majority of the information needed to construct this summery map. Section 4 - Objectives and Policies Objective G - The current Wetland Conservation Act provisions (8420,0540) include a section on maintaining the phosphorus rernoval efficiency of stormwater ponds used for wetland mitigation/ replacement. If the City of Arden Hills plans to use stormwater ponds or portions of them for wetland replacement credits in the future, the LWMP is required to have language addressing this new provision. Section 5 - Implementation Program The Implementation Program focuses on the feasibility and construction of several stormwater improvement projects. The RCWD applauds the City of Arden Hills prior efforts to identify this need and develop this implementation program. The RCWD will expect to be kept up to date on the outcomes of the feasibility studies and their implementation. The RCWD will accept this implementation program and CIP with this understanding. . CostjBenefit for Pollutant Removal The cost/benefit analysis conducted as part of this planning process has not taken into account several items, specifically Table 9 should include columns identifying the pollutant removal capability of each practice. The newly published "Minnesota Urban Small Sites BMP Manual", prepared for the Metropolitan Council by BARR Engineering, 2001, should be referenced as a local document that identifies many alternatives to traditional retention/ detention ponds and explains in detail the benefits provided. Costs were not included in this local manual because they were deemed too variable early in the planning process (Oberts, G., personnel communications). Weighing the benefits on the cost of the stormwater treatment facility alone does not account for the differing nature of pollutant removal r.apabilities of, for example, infiltration practices wbich reduce the overall volume of water leaving the site and significantly reduces the pollutant removal well below that of a standard NURP pond. This part of the Draft Plan specifically identifies detention ponds as the stormwater BMP of choice for the City of Arden Hil1s. This is in contradiction to recommendations and strategies identified in the Final Report - Arden Hil1s Water Quality Task Force. This report specifically recommends including RCWD infiltration BMPs as first choice planning options and maximizing long-term benefits to cost using Metro Council's BMPs and RCWD infiltration practices in the Water Management Plan. These recommendations should be reflected in the l.5WMP. Appendices Appendix A - Please include RCWD stormwater permitting authority under WMO responsibility. e