03-02-2017 Parks & Rec Packet - Laserfiche WebLink

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10062 Flanders Court NE – Blaine, MN 55449 – Ph: (763) 780-0450 Fax (763) 780-0452 Memo-022317-PB (Nadeau Wildlife Park Rain Garden).doc Memo TO: Honorable Chair & Park Board Members FROM: Lee Elfering, City Engineer DATE: February 23, 2017 RE: Nadeau Wildlife Park / Savage Lake Access Infiltration Practices The City’s 2017 Street and Utility Improvement project includes the reconstruction of Lake Shore Avenue and East Rose Place from Lake Street to Jackson Street. One of the requirements that must be met as part of the Watershed permit for the project is the abstraction/infiltration of 1.1-inches of runoff from the impervious surfaces impacted. The City typically meets this requirement by working with adjacent homeowners who volunteer to allow construction of rainwater gardens in the boulevard areas in front of their properties. In the case of Lake Shore Avenue and East Rose Place the boulevard and street grades along with the limited resident interest in rain gardens required that we look at other areas for construction of infiltration practices. The two areas identified were the Lake Street right-of-way from the intersection of Lake Street and Lake Shore Avenue down to Savage Lake and Nadeau Wildlife Park south of Lake Street. Both these areas are owned/controlled by the City and are of sufficient size to allow the construction of an infiltration practice and the proposed impacts are shown on the attached exhibit. Lake Street Right-of-Way The infiltration basin proposed at this location would be constructed at the top of the easement prior to the steeper slopes down to the lake. We have used unimproved road rights-of-way for infiltration practices on other street projects, however we are aware that there has been discussion about using this right-of-way as an access down to Savage Lake and the construction of an infiltration basin in this area would be competing for the same space. If the City would like to maintain the possibility of utilizing this right-of-way for future access to the lake we would not recommend a garden at this location. Nadeau Wildlife Park In addition to the rain water garden proposed on the Lake Street right-of-way an infiltration area will also be required in Nadeau Wildlife Park to meet the infiltration requirements. We are proposing the construction of an infiltration area along the east end of the park to maintain a large green area between the infiltration area and the playground area on the west side of the Park. There is a horseshoe pit in the area of the proposed basin that would need to be removed or relocated. The basin shown on the attached sheet has been sized to meet the infiltration requirements assuming all other