Laserfiche WebLink
Metadata
Document management portal powered by Laserfiche WebLink 9 © 1998-2015 Laserfiche. All rights reserved.
<br /> <br />Arden Hills Draft SWMP - 2 <br /> <br />'he City should consider amending their ordinances and this requirement to allow for flexibility in .. <br />determining the most cost-effective and beneficial means of treating stormwater runoff. ,., <br /> <br />Section 3 - Hydraulic and Water Quality Analysis <br />The existing information should be summarized in a figure that identifies the existing water quality <br />treatment with regard to NURP standards for each subwatershed (see attached example). This figure <br />will allow for identification of water quality, treatment ponds and subwatersheds that will benefit <br />from retrofitting or regional water quality ponding. Identify locations of non-treated discharges to <br />City Lakes and Creeks for future retrofit opportunities. It appears that the City has the majority of the <br />information needed to construct this summery map. <br /> <br />Section 4 - Objectives and Policies <br />Objective G - The current Wetland Conservation Act provisions (8420,0540) include a section on <br />maintaining the phosphorus rernoval efficiency of stormwater ponds used for wetland <br />mitigation/ replacement. If the City of Arden Hills plans to use stormwater ponds or portions of them <br />for wetland replacement credits in the future, the LWMP is required to have language addressing this <br />new provision. <br /> <br />Section 5 - Implementation Program <br />The Implementation Program focuses on the feasibility and construction of several stormwater <br />improvement projects. The RCWD applauds the City of Arden Hills prior efforts to identify this need <br />and develop this implementation program. The RCWD will expect to be kept up to date on the <br />outcomes of the feasibility studies and their implementation. The RCWD will accept this <br />implementation program and CIP with this understanding. . <br /> <br />CostjBenefit for Pollutant Removal <br />The cost/benefit analysis conducted as part of this planning process has not taken into account <br />several items, specifically Table 9 should include columns identifying the pollutant removal capability <br />of each practice. The newly published "Minnesota Urban Small Sites BMP Manual", prepared for the <br />Metropolitan Council by BARR Engineering, 2001, should be referenced as a local document that <br />identifies many alternatives to traditional retention/ detention ponds and explains in detail the <br />benefits provided. Costs were not included in this local manual because they were deemed too <br />variable early in the planning process (Oberts, G., personnel communications). Weighing the benefits <br />on the cost of the stormwater treatment facility alone does not account for the differing nature of <br />pollutant removal r.apabilities of, for example, infiltration practices wbich reduce the overall volume <br />of water leaving the site and significantly reduces the pollutant removal well below that of a standard <br />NURP pond. <br /> <br />This part of the Draft Plan specifically identifies detention ponds as the stormwater BMP of choice for <br />the City of Arden Hil1s. This is in contradiction to recommendations and strategies identified in the <br />Final Report - Arden Hil1s Water Quality Task Force. This report specifically recommends including <br />RCWD infiltration BMPs as first choice planning options and maximizing long-term benefits to cost <br />using Metro Council's BMPs and RCWD infiltration practices in the Water Management Plan. These <br />recommendations should be reflected in the l.5WMP. <br /> <br />Appendices <br />Appendix A - Please include RCWD stormwater permitting authority under WMO responsibility. e <br />