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City of Mounds View Page 3 Ardan Avenue Drainage Subdistrict Analysis 000435-07129-0 Residents adjacent to street low points are familiar with how the current storm sewer system operates and due to the lack of complaints regarding street flooding in the project area, we presume that residents generally don’t perceive this operation to be a problem. As is the case with other fully developed communities, the excessive cost of improvements generally becomes the limiting factor when attempting to address local flooding issues by upsizing existing storm sewer systems. It does not seem to be the most effective use of City resources to improve storm sewer in areas within the project area that haven’t historically reported drainage problems (e.g. along Sherwood Road). The increase in storm sewer capacity in the Ardan Avenue area doesn’t appear to match the large capital outlay for the improvements. 3.1 RECOMMENDED STORM SEWER IMPROVEMENTS This new analysis re-examined the improvements identified in the 1989 Report. Following the approach outlined in the previous section of this Report, revised recommendations for storm sewer improvements within the Ardan Avenue Drainage Subdistrict are identified. Map 1 in Appendix B presents these recommended storm sewer improvements that address Goal 1 of this analysis. The storm sewer improvements identified on Map 1 in Appendix B do not meet a 5-year storm sewer design standard for the reasons outlined above; however, these improvements were designed to address the following parameters: Eliminate the need to construct the proposed East Detention Pond. Provide additional storm sewer conveyance capacity to reasonably address the known drainage issues in the project area, notably the rear yard nuisance flooding reported north of Ardan Avenue. Be designed economically. Be designed to utilize the available capacity of the 48-inch stub at the intersection of Long Lake Road and Ardan Avenue. The storm sewer improvements identified on Map 1 in Appendix B maintain much of the existing trunk storm sewer in the study area. These improvements also follow a design approach along Ardan Avenue similar to the approach identified in the 1989 Report, namely constructing new trunk storm sewer in Ardan Avenue and abandoning the existing storm sewer connections from Ardan Avenue to the existing trunk storm sewer north of Ardan Avenue. This approach, along with the other improvements presented on Map 1 in Appendix B, seeks to address the parameters mentioned above by both increasing the storm sewer conveyance capacity in the study area by adding a proposed trunk storm sewer in Ardan Avenue and reduce the conveyance burden on the existing storm sewer in Sherwood Road and north of Ardan Avenue by abandoning certain connections to these existing sewers. Detailed Ration Method design calculations for both the existing storm sewer system in the study area and the storm sewer improvements recommended in this Report are included in Appendix B. Based on the design parameters identified above, the new storm sewer shown on Map 1 in Appendix B meets roughly a 2-year storm sewer design standard. 3.2 IMPACTS ON THE 2009-2010 STREET AND UTILITY IMPROVEMENT PROJECT A portion of the study area for this analysis incorporates streets included in the City’s 2009-2010 Street and Utility Improvement Project (SUIP), namely Sherwood Road between Groveland Road and Long Lake Road and Redoak Drive from Sherwood Road to north of Ardan Avenue. The 2009-2010 SUIP is currently in the design phase of the project; therefore it is critical that this Report clearly outline how the proposed improvements identified on Map 1 in Appendix B and those in the 1989 Report impact the 2009-2010 SUIP. A summary is as follows: