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ARDEN HILLS CITY COUNCIL – AUGUST 29, 2016 6 8. NEW BUSINESS A. 2015 PMP Venus Drainage Acting Public Works Director Anderson stated the 2015 PMP project occurred in the Venus Crystal neighborhood in 2015. The roadway was modified to add concrete curb and the storm sewer system retro fitted to match the concrete curbing. The design of the roadway called for the road to be lowered slightly at the low point in front of 1776 Venus Avenue. As part of the design, the crown in the road was also eliminated to provide a better fit to the existing driveways in the area which are flat on one side of the street and steep on the other. As an additional storm water treatment BMP, a sump catch basin with a filter designed to trap sediment was installed in this location and two other locations. Acting Public Works Director Anderson reported staff was contacted by the resident at 1776 Venus Avenue with concerns over the storm sewer capacity and street drainage backing up onto their property as far back as the garage and house. Staff investigated the storm system and found debris clogging the screen that was limiting the flow of storm water through the screen. Public Works has removed these screens based on this result. In rain events since the screen was removed the storm water backup onto the lot has been less but still does, in heavy rains, encroach on to the driveway. Acting Public Works Director Anderson commented based on the observations of the system operations the engineer has recommended two changes to the storm drainage system. The first is to add additional inlet capacity at the low point in the road just west of the driveway to 1776 Venus Avenue. This additional catch basin would allow for storm water to get into the system faster as well as provide some redundancy should one inlet get clogged with debris. The result of this would decrease the ponding in the street and backup into the driveway at 1776. As with any storm design there is always a larger storm event that may come along and overwhelm the system. In th ese cases, it is important to have a route for storm water to escape the low point in the road overland that does not involve flooding structures. This low point in the street has a potential overflow route that can be created with a minimal amount of grading. The second recommendation is to grade an overflow swale along the east property line of 1776 Venus Avenue that will provide and overland route for storm water to flow should a rain event exceed the capacity of the system. The other benefit of having an emergency overflow route in place is that if the house at 1776 Venus Avenue experiences water in the basement and the street water is show not to contribute to the problem, then the wet basement is a result of roof runoff or yard drainage or some other factor unrelated to the street. City staff support pursuing both of the options recommended by the engineer. Acting Public Works Director Anderson explained staff met with both the owners at 1776 and 1768 Venus Avenue who share the common lot line where this overflow route is proposed. He described the proposed grading and stated the City has obtained their approval of this approach. This work is proposed to take place within the existing drainage easement. Acting Public Works Director Anderson stated quotes were solicited for this work and the low price for the catch basin is from C.W. Houle Inc. The City has contracted with C.W. Houle in the