Agenda - Planning Commission - 04/03/2003

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I I I I i I I I I I I I ! I I I I I I emergency overflow for the natural existing wetlands and the basements are below the natural EOF. One explanation of the 100-year event is that the bottom of the wetland is an 860 and is relatively dry. They were instructed by staff to look at outlet of the pipe between the two lots at 866. How they would reach the 866 would be if it were filled or back to back events or a very large event over the 100 year. They can work with staff to make sure they agree with curve numbers and calculations. Principal Planner Trudgeon inquired if the Engineer was stating that with a 100 year event there would be water going over the existing easement. Susan ?, replied yes. If they use the worse case scenario water would go up to 867, which would definitely be on Ms. Dvorak's property. Councihnember Elvig inquired if there was a possibility of connecting to the existing pipe at 146th Avenue. Susan ?, explained that the pipe on 146th Avenue has no sloPe to it. She explained that it drains to the south to the existing catch basins and than to the east. There is no way to really lower the pipe without reconstructing 146t}~ Avenue. Councilmember Elvig inquired if there was any type of pumping apparatus that could be used. City Engineer Jankowski replied that staff would not want to maintain a mechanical lift station roi' storm water, but there a munber of things they can look at to alleviate the situation. Councilmember Elvig inquired if staff was comfortable that they could accomplish something to keep water from going onto Ms. Dvorak's property in a 10 year event. City Engineer JankowSki replied that he did not have that information, but they could easily run those numbers to answer the question. Chet Harrison, Loucks Associates, explained that the bottom of the existing swail does not get filled in because they assumed the bottom of the Pond was where the existing pipe is. Leaving the pond as is he did not believe that two 100 year back to back storms would get to the pipe. Councilmember Strommen stated that she would like to see the drainage issue resolved before moving forward as well as the landscaping issues especially in the transition area. She also wants to ensure that there are adequate provisions in place to prevent oak wilt. She expressed concern over the length of the driveways and how it relates to off-street parking, especially in the cottage units. And she was still not convinced that the south-west trail connection was necessary. Councilmember Zimmerman stated that he felt that the proposed density was to high Since the development is surrounded by lots that are 10,800 square feet. He inquired as to why the developer was proposing lot sizes as small as 5,000 Square feet. City Council/February 25, 2003 Page 13 of 24 P33