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09-16-19 CC Special WS MinutesCITY OF SHOREWOOD MANOR PARK CITY COUNCIL SPECIAL WORK SESSION MEETING 6:00 P.M. MONDAY, SEPTEMBER 16, 2019 MINUTES 1. CONVENE CITY COUNCIL WORK SESSION MEETING Mayor Zerby called the meeting to order at 6:03 p.m. A. Roll Call Present: Councilmembers Johnson and Labadie; City Administrator Lerud and Director of Public Works Brown. B. Review Agenda Johnson moved, Labadie seconded, approving the agenda as presented. Motion passed 3/0. 2. MANOR PARK POND REPORT Administrator Lerud said the council met in Manor Park last October and heard the concerns of the residents about the water quality in the Manor Park pond. Following that meeting the city accepted a proposal from Barr Engineering to analyze the pond conditions and prepare recommendations on how to best improve the conditions. He said Barr surveyed and took samples of the pond which culminated in the late August report that was shared with the neighborhood residents. Lerud said Kevin Menken and Jennifer Koehler from Barr Engineering are here tonight to present their findings, recommendations, and answer questions. Kevin Menken, Senior Environmental Engineer at Barr Engineering discussed the types of phosphorus and how they impact the pond. He said that based on the small size of the watershed area, and their Bathymetric survey, he recommended using Alum to control the phosphorous. He said that Alum binds to phosphorous creating a floc that then floats to the bottom of the pond and it is sequestered there. He said Alum is non -toxic and there are many agencies and cities that use Alum to control phosphorous. He said that using it will help improve downstream water quality because the phosphorous will be captured and stored in the Manor Park pond. Menken explained how Alum is applied and said within a day it floats to the bottom of the basin and is not washed out provided it is not applied during a rainstorm. He said it is not toxic to any fish that are in the water, or birds, and the only potential issue would be applying too much Alum which could change the pH of the water, and that could potentially be harmful. He said firms that apply Alum should be making the correct calculations for dosage which would eliminate that issue. There was a question about the fountain that was previously in the pond and if that could be an effective treatment for the phosphorous. Jennifer Koehler, Senior Water Resources Engineer at Barr Engineering said that aeration can be effective if it is done right. If it is not, then it creates a situation where the Alum treatment is less effective because the water is stirring up the phosphorous in the water. Menken said that their recommendation is using the Alum because it is a less expense option that constructing, operating, and maintaining an aeration system. CITY OF SHOREWOOD SPECIAL WORK SESSION COUNCIL MEETING MINUTES SEPTEMBER 16, 2019 Page 2 of 2 Koehler said that once the water clears and the phosphorous is sequestered at the bottom, it is very likely that aquatic plants will appear because sunlight will reach the bottom. She said if there were lily pads in the past, there would likely be lily pads in the future. A resident asked if the Alum would pose a problem to the ground water. She said that most people are on wells in the area. Menken said no. Once the Alum bonds with the phosphorous it becomes non soluble. In addition, he said he recalled in an earlier study, there was clay below the peat, which would prevent much water from going through. Koehler said that Alum is used by some cities in the treatment of water. She said that Minneapolis and St. Paul use Alum to treat their drinking water because they get it from the Mississippi River, and it is non - toxic. There was a question about dredging the pond bottom. Menken said that there is roughly four inches of accumulated sediment at the bottom of the pond, which is on top of native peat. He talked about the difficulty of removing such a small amount, and in doing so, he said, additional phosphorous could be released. He recommended using Alum to improve the water quality. It was reported that one Alum treatment has been done on the pond in August, and one more is scheduled for later this month. Director of Public Works Brown said that the city was working with Lake Restoration to get on a regular maintenance program for the pond starting next year. He said he did not recall the exact cost of the treatment. Mayor Zerby said that he likes the idea of Alum treatment because it is cost effective and it appears it will do a good job cleaning up the water. He suggested that the city take regular water samples as the treatment starts to track the effectiveness of the treatments. 3. ADJOURN Labadie moved, Johnson seconded, to adjourn the meeting. Motion passed 3/0 and the meeting adjourned at 6:50 P.M. ATTEST: - -E Sc erby, M r t Sandie Thone, City Clerk