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Feasibility Report Northeast Lino Lakes Drainage Improvement Project WSB Project No. 02029-790 Page 8 option benefits 710 acres, of which 495 acres are in Lino Lakes. This option was not recommended due to adverse impacts to Clearwater Creek including increased discharge and potential bank erosion. Option 3: New Outlet to Peltier Lake and Crossing Under I-35E When considering this option various alignments between 20th Avenue and Peltier Lake were considered. The objective in recommending an alignment was to minimize impacts to undeveloped parcels and reduce associated easement acquisitions. Alternative A – Open Channel Conveyance This option includes open-channel flow through a 10 foot deep ditch system (Appendix A, Figure 6). While feasible and consistent with the City of Lino Lakes’ I-35 Final Corridor Alternative Urban Areawide Review, it requires double the land acquisitions in a northern alignment resulting in the cost being 20 to 25 percent higher than Alternate B; and thus is not recommended. In addition, RCWD staff noted they would not permit it in a southern alignment due to potential wetland impacts. Alternative B - Storm Sewer Pipe Outlet This option is the preferred alternative and includes a new outlet at Peltier Lake via a 72- inch storm drain, or equivalent design, from Peltier Lake to I-35E to capture the ACD 55 and ACD 72 drainage systems upstream of I-35E and collect runoff from the study area (Appendix A, Figure 6). There is a proposed mixed-use development between 20th Avenue and I-35E. The development would provide surface drainage via a series of connected ponds from I-35E to the 20th Avenue. If this development proceeds, the surface drainage system would replace the proposed pipeline between 20th Avenue and I-35E. The area above the pipe could be used for public greenspace, as well as storm water ponding as this area develops in the future. Alternative C – Combination Open Channel and Storm Sewer Outlet We also considered a hybrid solution that would include a combined ditch and pipe system in lieu of a 72-inch storm drain between 20th Avenue and Peltier Lake. A smaller pipe was considered that would surcharge to an open-channel greenway above the pipe. Due to pipe depth and the pressure required to surcharge, this concept would require double the land acquisition than Alternative B. Alternative B is recommended as it provides surface water treatment, water quality improvements and rate control through draining storage systems effectively and efficiently, thereby minimizing the bounce in ponds from successive storm events. It also provides a known normal water elevation in the low areas, around which the designers may build future development to be safe from flooding. Option 3 also includes a crossing under I-35E near the existing ACD 55 crossing (Appendix A, Figure 6). Final design and coordination with RCWD and MnDOT will determine if this crossing is a single crossing or two smaller crossings under I-35E.