06-06-2016 Council Packet - Laserfiche WebLink

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regional ponding facilities with gate structures to detain peak storm flows and prevent increasing the flood levels on Peltier Lake. The new greenway option includes the new culvert crossing under I-35, storm sewer and regional storage facilities, but rather than a pipeline from Peltier Lake to 20th Avenue, an open channel design is being considered. The conceptual alignment and typical cross- section have been developed with the intent to provide live storage for large flood events, to be in agreement with the City’s AUAR and greenspace requirements, as well as to avoid wetland impacts as much as possible. The final design of the channel will require special attention to the wetlands so that the project does not inadvertently drain them via lateral effects. The greenway option also provides additional water quality treatment opportunities for the study area. At the May 25, 2016 Environmental Board meeting, the feasibility study was approved with the recommendation that additional water quality treatment be incorporated as possible. Since the last Council update, staff met with adjacent landowners and RCWD to review all the options considered for the alignment between 20th Avenue and Peltier Lake. Based on these meetings a technical memo was incorporated into the feasibility study as Appendix F. The feasibility project cost for the green way option will be incorporated prior to Council accepting the feasibility. The cost should not increase from the draft report enclosed. The goal is find the most cost effective option considering input from landowners and Rice Creek Watershed District. The proposed project includes a combination of greenway and pipe to accommodate stakeholder current and future needs. Requested Council Direction The feasibility study will be presented on June 27, 2016 for Council consideration to accept the feasibility study. Attachments 1. Draft Feasibility Study 2. Feasibility Study Appendix F – Design Options Considered