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Lino Lakes Outlet Study January 22, 2015 Page 2 K:\02029-790\Admin\Docs\Outlet Alternatives Memo_Sequencing.doc data used in the Level 1 analysis along with the proposed wetland boundaries. Historic aerial photos of the area are attached (Appendix B). The alternatives analysis also considered the Wetland Preservation Corridor that has been established by the City of Lino Lakes. Based on the results of the Level 1 delineation, a Level 2 delineation may need to be performed during the growing season adjacent to the preferred pipe alignment. This will ensure that the pipe is placed in a manner that avoids or minimizes wetland impacts. Sequencing Analysis WSB & Associates has completed an analysis of a range of alternatives consistent with WCA Rules 8420.0325 and 8420.0520. The preferred alternative will ultimately connect to a system under I-35E. The preferred alternative will collect overflow from this system; therefore impacts to wetlands east of I-35W are not anticipated. Major differences between the alternatives west of I-35E are based on pipe or open channel options. Alternative impact comparisons are detailed in Table 1. Each of the alternatives described below are shown on Figure 2. Alternative 1: Western Pipe/Open Channel Option 1 (Northern-most option): This option will use Eastern Pipe Option 1. At the 20th Avenue connection a pipe or open channel will connect to the eastern pipe and continue its flow west to Peltier Lake. The individual benefits and drawback of this option area summarized below and shown on the attached figure: Benefits of this option: • Minimal temporary wetland impacts anticipated with pipe placement. Because a pipe would be used, no secondary impacts resulting from lateral effect area expected. • No impacts to Wetland Preservation Corridor. Drawbacks of this option: • Wetland impacts could occur with an open channel option as a result of secondary drainage (lateral effect). This effect would need to be calculated and impacts would require replacement at an estimated 2:1 ratio. • More difficult to get drainage from southern portion of western parcel to the north. • Western parcel property owner prefers an option that utilizes more of the low land to the south of the parcel. • Private property impacts to the parcels north of the boundary are possible. Alternative 2/4: Western Pipe Option 2 & 4 (central pipe): Through the Mattamy Homes parcel, the pipe could use Eastern Pipe Option 1 or Eastern Pipe Option 2. The Eastern Pipe Option 2 is likely the more appropriate connection. The pipes would then connect to the western parcel under 20th Avenue. From 20th Avenue, the piping could go one of two ways using Western Pipe Option 2 or