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Estimated date of substantial completion (Dependent on completion of Great Northern Trail <br />Forcemain): November, 2020 <br />Following completion of the proposed improvements, a public hearing is held to set the final <br />assessment amounts. Estimated date: November 2, 2020 <br />III. EXISTING CONDITIONS <br />A. WINDSOR PARK 3RD ADDITION <br />Windsor Park 3,d Addition is located along County Road 33 west of County Road 1. The <br />development's 88 lots are serviced by a shared low pressure sanitary sewer system. The <br />system converges to a 3-inch PVC low pressure forcemain that discharges to a drainfield and <br />recirculating sand filter on the east side of the development. Per city standards, it is estimated <br />that the 88 existing homes produce approximately 25,000 gallons per day of flow into the <br />wastewater system. <br />The existing drainfield is limited in its ability to treat effluent compared to that of a <br />wastewater treatment plant. Located in the Windsor Park neighborhood, it occupies space that <br />could be used for other applications. The cost to maintain and efforts required to monitor <br />private drain fields can be substantial. Should the drainfield system fail, the impacts to those <br />served can include sewer backups into homes and excessive emergency repair costs. <br />B. GREAT NORTHERN TRAIL FORCEMAIN <br />A 6-inch sanitary forcemain that follows the Great Northern Trail is planned to be <br />constructed in 2020. It begins at the Elk River Landfill and conveys leachate south and ties <br />into the existing sanitary gravity sewer north of Meadowvale Elementary School. <br />C. SURROUNDING NEIGHBORHOODS <br />The neighborhoods between Windsor Park 31d Addition and the Great Northern Trail are not <br />currently served by any municipal sewer system. The neighborhoods to the south of Windsor <br />Park 3,d Addition are served by a similar low pressure sanitary sewer forcemain and <br />drainfield. All of these neighborhoods are outside of the current planned urban service area of <br />the City. <br />IV. PROPOSED IMPROVEMENTS <br />A. SANITARY SEWER <br />The proposed sewer improvements will connect the existing low pressure sanitary forcemain <br />on the east side of the Windsor Park 31d Addition to the 6-inch forcemain Great Northern <br />Trail. The current drainfield and recirculating sand filter should be removed once the new <br />system is operational. Windsor Park 3,d Addition's 3-inch PVC low pressure sanitary <br />forcemain will transition to an 8-inch gravity sewer near the current recirculating sand filter. <br />This location would be the point of ownership transfer. The 8-inch gravity sanitary sewer will <br />run trenchless along County Road 33 (Ranch Road NW) from the transition point to the <br />planned lift station location about 3,230ft to the east. Manholes will be installed at standard <br />spacing. <br />Starting at the lift station, a 6-inch sanitary forcemain will run trenchless along County Road <br />33 (Ranch Road NW) to the Great Northern Trail. To stay within the utility easements and <br />clear of the trail underpass, the 6-inch sanitary forcemain will be open cut and installed <br />approximately 200 ft south to tie in to the existing 6-inch sanitary forcemain. A 6-inch check <br />valve will be required on the upstream side of the connection point for each the Great <br />Northern Trail forcemain and the Windsor Park forcemain to prevent backflow issues. <br />Prepared by: Bolton & Menk, Inc. <br />Windsor Park 31d Addition — Sewer Connection I R16.120038 <br />Page 2 <br />