Agenda - Public Works Committee - 05/16/2023

Home

City Engineer/Public Works Director Westby stated that numerous terms can be used for stormwater ponding areas but confirmed that the intent would be for the water to infiltrate into the soil and is not meant to have standing water for long periods of time. Chairperson Riley asked if the water would drain at the same rate, it currently does. City Engineer/Public Works Director Westby provided details on the current path of drainage and noted that this area would become deeper and therefore water could sit for longer than it currently does. He stated that they are not changing the drainage area and therefore it would be the same water volume that currently drains to this area, though it would drain more quickly due to the storm sewer. He did not think the chemicals used for lawn treatment at the park would be different than what is used on residential yards. Councilmember Woestehoff stated that the resident he spoke with had questions about the timeline of events as the resident was planning to have company for a wedding. City Engineer/Public Works Director Westby replied that construction is anticipated to begin in June. He noted that staff will attempt to work with the homeowner to avoid conflict to the extent possible. Mr. Lubarski asked what would happen if his well were to be polluted as a result of the project. Councilmember Musgrove referenced the parking lot improvement and asked if there would be more area for infiltration in that area as part of the project. Assistant City Engineer Feriancek stated that there would be two lowered medians as part of the design that would handle the first inch of rainfall from the parking lots, which will significantly reduce the pollutants from the parking lot. He stated that there will also be sump manholes that collect sediment and unwanted materials. He stated that the water reaching the drainage basin after the project will be cleaner than it currently is. Chairperson Riley asked the purpose of having to put in a new pipe rather than leaving the ditch as is. Assistant City Engineer Feriancek stated that the existing ditch is very flat and at grade with 161 st until you reach the pond area. He stated that with the storm sewer system they need to maintain at least four feet of cover over the pipe and then run it at grade to daylight into the pond. He stated that the outlet for the system is approximately six feet below the existing grade of the pond, which led to the need for additional depth in the pond. He stated that water currently runs over the street, which is a safety hazard. He explained that a road would not be designed in that manner today. Chairperson Riley commented that these are drainage improvements, and the area will drain better as a result of this project. He asked if the resident was amenable to the concept of transplanting trees. Public Works Committee / April 18, 2023 Page 8 of 9