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Feasibility Report Northeast Lino Lakes Drainage Improvement Project WSB Project No. 02029-790 Page 9 4.2. Proposed Drainage Improvements The new outlet to Peltier Lake and crossing under I-35E via a storm sewer pipe system is recommended as the most cost-effective alternative. The proposed project (Appendix A, Figure 7) includes: A. New outfall to Peltier Lake B. New 72-inch storm drain from 20th Avenue to Peltier Lake Drive C. New 60-inch storm drain crossing under I-35E to regional storage facility D. New storm sewer to collect developed runoff from the east side of I-35E E. As feasible incorporate a public greenway corridor with additional water quality best management practice (BMP) features that could treat surface runoff before entering the storm main. F. Outlet control structures with gates on selected regional storage facilities to minimize the risk of storm water runoff from adversely impacting flood levels on Peltier Lake G. Preserve the agricultural drain tile system to maintain upstream drainage rights until all land within the study area develops. Drain tile may be abandoned or realigned as development progresses, at the benefitted landowners’ expense and discretion. The conceptual layout and system details are provided in Appendix C. Additional design requirements for land development within the study area are summarized in Appendix D. 4.3. Storm Sewer and Stormwater Management The City’s proposed storm sewer system and drainage design requirements will be in conformance with the City’s performance standards, and as permitted by RCWD. Construction of a stormwater collection and conveyance system will be necessary to direct stormwater to the new pipeline and ultimately to Peltier Lake. This system will reduce flooding within the study area and improve drainage conditions throughout the Northeast Lino Lakes Area. There are multiple ponding locations proposed with the Northeast Lino Lakes Comprehensive Stormwater Management Plan. At this time it is proposed to utilize existing wetland complexes for flood storage by providing an outlet control structure with operable gate at the normal water level. In the event of a 1-percent chance design storm, the gates can be closed to minimize the risk of increasing the flood stage on Peltier Lake, and the wetlands would store the water until the gates are opened after the flood threat on Peltier Lake has passed. The exact location and design of these regional BMPs will be determined as the design progresses. It will be expected that the storage area will experience a significant bounce in elevation during 100-year storm