8.3 SR 02-06-2023 - Laserfiche WebLink

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Trunk Watermain: Modeling indicated that the existing 12-inch watermain can be extended north along Elk Lake Road NW starting at the intersection of Elk Lake Road NW and Meadowvale Road NW and then east along 205th Avenue NW and west along Ranch Road NW. Two (2) smaller loops are being proposed along future developments north of Ranch Road NW and along various existing streets such as Queen Street NW, 214th Avenue NW, Naples Street NW, 212th Avenue NW, Lander Street NW, and 209th Avenue NW. The 12-inch watermain along 205th Avenue NW can transition into a 16-inch watermain in the gravel mining areas and continue south along 205th Avenue NW and Proctor Road NW until connecting with the existing 16-inch watermain at the intersection of Proctor Road NW and 195th Lane NW. To serve the eastern areas, the existing 12-inch watermain on Holt Street NW should also be extended around the eastern and northern boundary of the study areas. Additionally, a smaller 12-inch loop can be created by extending 12-inch watermain along 197th Avenue NW, Lowell Street NW, 198th Avenue NW, Norfolk Street NW, and 199th Street NW. It is recommended that the 16-inch and eastern 12-inch watermains be extended north as development continues beyond 2040 to serve the ultimate boundary of the northwest service areas. Eight-inch watermain can be extended from the proposed 12-inch and 16-inch trunk loops to provide water service to the northwest study area via smaller watermain loops. The smaller 8-inch watermain loops shown in Figure A13 are not definitive and their final location will change based on future development layouts. Wells: The two (2) 850 gpm wells proposed for the northwest service areas should be drilled in the High Zone 2 shown in Figure A13. These wells can be operated using the proposed water tower for the zone. Water from the High Zone 2 will flow to the other northwest areas (High Zone 1, Low Zone 1, and Low Zone 2) via pressure reducing stations. Water Towers: A new 1.0 MG water tower is proposed for the northwest areas to be located in High Zone 2. Water Treatment Plants: It is strongly recommended to provide water treatment via direct pressure filtration at the proposed wells in the northwest areas. A single plant could be used to treat water from both wells. Pressure Zones: Modeling indicated that the northwest areas cannot be annexed to the system's main pressure zone without pressure regulating infrastructure. Given the ground elevations of the study area, it is recommended to serve the northwest areas with two (2) larger high pressure zones and two (2) smaller lower sub-zones. The hydraulic grade lines (HGLs) recommended for each of the zones varies from 1,120-ft to 1,181-ft and are shown in Figure A13. Dividing the northwest study areas into the pressure zones shown in Figure A13 would maintain the water pressures between 39 psi and 84 psi for average day demand conditions and between 37 psi and 84 psi for peak hourly demand conditions as shown in Figures A14 and A15 in AppendixA. Although some areas are projected to experience water pressures lower than 50 psi, it is not recommended to serve the northwest study area with more than four (4) pressure zones as it would result in a significant increase in operation requirements for utility staff. Furthermore, the areas that are projected to have a water pressure below 50 psi are small in comparison to the size of the entire study area. The ultimate developments of the northwest areas can be served by the High Zone 2. Booster Stations: As shown in Figure A13, two (2) booster stations (BS-1 and BS-2) are recommended to supplement the well pumping capacity of the northwest study areas. Given the pumping capacity recommended for each booster station, each station should have at least two (2) pumps. Both booster stations can be built underground in a vault structure with an access hatch. The use of the booster stations can be slowly phased out as additional wells are drilled in the northwest areas. Once additional wells are drilled, the booster stations can be used for backup/emergency purposes or be completely eliminated. PRVs: A total of five (5) PRVs are recommended to serve the study area. Two (2) PRVs (PRV-1 and PRV-3) will be used to serve the two smaller low pressure zones, two (2) PRVs will be used to recirculate water back to the system's main pressure zone, and a fifth one will be used to connect the High Zone 1 with the High Zone 2. Recirculating water from the high zones back to the main zone will allow for constant water movement within the northwest areas which should eliminate water stagnation in the water tower at the beginning when water demands are lower. The use of Feasibility Report Northeast & Northwest Urban Service Area Expansion Study City of Elk River, MN WSB Project No. 020010-000 Page 13