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<br /> Ms. Patricia Arlig, P,E, <br />. Page 2 <br /> August 26, 1992 <br /> The City's intent to use regional detention areas whenever possible is commended. One potential <br /> use of the management plan would be to provide ponding parameters for regional ponds in the <br /> areas which remain undeveloped within the City. Of particular concern to the Watershed District <br /> is the commercial area adjacent to Round Lake. Such a planning effort would be similar to the <br /> historic plans prepared for the Gray Fox Road area west of Lexington Avenue and the Land 0' <br /> Lakes corporate area. <br /> As currently assembled, the plan qualitatively discusses results of the runoff modeling <br /> performed for the plan, We highly recommend inclusion of this data in the plan so that peak flow <br /> rates and approximate 100-year flood elevations are available. Conversations with Brian Miller <br /> noted that he had concerns regarding the accuracy of the TR-20 pond routing subroutines. We <br /> feel the information is still worthy of merit and could at least be included as a technical appendix <br /> with limited distribution. Many of the storm water plans prepared across the metropolitan area <br /> have been conducted using the TR-20 model and the use of this data in the management plan, we <br /> feel, does not pose a risk to the City. <br /> Policy 2,3 states that outlets will be provided for land-locked areas. Land-locked areas obviously <br /> provide maximized runoff control and treatment of water quality, While there are areas where <br /> existing development may be subject to flooding, many land-locked areas should be preserved or <br /> maximize the available storage if an outlet is provided. <br />. District review of the TR-20 modeling results is still being performed and we will be forwarding <br /> additional correspondence when this review is completed. <br /> Individual Sewage Treatment Systems <br /> This portion of the management plan conforms with the District's plan with the exception that an <br /> inspection program for the few remaining ISTS is not documented. <br /> Wetland Management <br /> The plan indicates that the City is interested in developing wetland protection regulations. Our <br /> comments regarding this are similar to the Runoff Management section in that we feel that the <br /> management plan should have sufficient detail from which to construct an ordinance. The <br /> wetland portion of the District's plan has considerable detail regarding wetland alterations and <br /> additional requirements such as posting of wetland maps, etc. which could be transposed in the <br /> Arden Hills plan, The area of wetland regulation is in a state of flux until such time that the <br /> Board of Water and Soil Resources promulgates rules for implementing the Wetland <br /> Conservation Act of 1991. Until the interim period is included, the Watershed District has elected <br /> not to surrender wetland permitting authority in an effort to provide consistent wetland <br /> regulations across the District. <br /> The management plan does include a copy of the National Wetlands Inventory. A "key" which <br /> explains the NWI symbology would be beneficial. In addition, we have found it helpful to have a <br /> conversion chart which relates NWI symbols with the more familiar USF & WS Circular 39 <br /> classifications (Type 1 through 8), <br />. <br /> -, <br />