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City of Mounds View Page 2 <br />Ardan Avenue Drainage Subdistrict Analysis 000435-07129-0 <br />In addition to these facts, the emphasis of storm water management in Mounds View has changed since <br />1989. Namely, the City has recently indicated a preference for avoiding the acquisition of land and <br />construction of large regional ponds, as was the case with discussions regarding the Spring Creek <br />Regional Pond. <br />2.1 ANALYSIS GOALS <br />Based on our review of the 1989 Report discussed above, Staff suggested and Council authorized us to <br />perform a new analysis of the Ardan Avenue Drainage Subdistrict, which is summarized in this Report <br />(“Report”). The goals of this new analysis are as follows: <br />Goal 1: Eliminate the proposed East Detention Pond and identify an alternate to the Sherwood Road <br />storm sewer proposed in the 1989 Report, while still improving the performance of the existing <br />storm sewer system in the study area. <br />Goal 2: Evaluate the existing level of local flood protection provided for homes adjacent to street low <br />points within the project area. <br />Goal 3: Identify rear yard nuisance flooding issues in the study area. <br />Goal 4: Recommend storm sewer improvements that are more financially feasible than those proposed in <br />the 1989 Report. <br />This new analysis is not done to the level of detail of the 1989 Report. Rather, the intent is to perform a <br />more brief and practical analysis to address the goals identified above. Each goal will be addressed <br />individually in the following sections. <br />3.NEW STORM SEWER ANALYSIS AND RECOMMENDATIONS <br />The 1989 Report begins with the premise that the drainage problems in the Ardan Avenue area are a <br />result of an undersized storm sewer drainage system. However, the locations of these drainage problems <br />are not specifically identified in the 1989 Report. Based on discussions with long-time City Staff regarding <br />past reports of flooding in the Ardan Avenue area, it is our understanding that these drainage problems <br />can be described as primarily rear yard nuisance flooding in areas north of Ardan Avenue, between <br />Fairchild Avenue and Long Lake Road. <br />To address these drainage problems, the 1989 Report proposed storm sewer improvements in the Ardan <br />Avenue area designed to meet a 5-year Rational Method design standard. Due to limited grade available <br />throughout the Ardan Avenue area, improving the existing storm sewer system to meet a 5-year design <br />standard required substantial storm sewer upsizing in both Ardan Avenue and Sherwood Road. In <br />addition, regional stormwater ponding improvements north of Sherwood Road (East Detention Pond) <br />were necessary to control the increased flow conveyed by the storm sewer improvements in Sherwood <br />Road (see Figure 3 in Appendix A). <br />While a 5-year storm sewer design standard would be ideal for new storm sewer construction; this design <br />standard is not met in older communities throughout the Metro area. Based on our review of the 1989 <br />Report, it is our conclusion that upsizing the existing storm sewer in this area to meet a 5-year design <br />standard does not appear to be warranted for the following reasons: <br />ƒLong-time City Staff indicate that past reports of flooding in the Ardan Avenue area were generally <br />isolated to rear yard areas north of Ardan Avenue, between Fairchild Avenue and Long Lake Road.