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3. WATER DISTRIBUTION SYSTEM ANALYSIS
<br />The City of Elk River uses a single water distribution system to serve the entire municipal service area. Due
<br />to the differences in ground elevation, the system is operated in two pressure zones, a low zone and a high
<br />zone, to maintain adequate water pressure throughout the system. Both pressure zones are interconnected
<br />only for emergency purposes and the use of booster stations and pressure reducing stations does not occur
<br />on a regular basis as the two zones remain isolated through valving. The existing water distribution system
<br />is depicted in Figure A8 in Appendix A. For the purpose of this study, the high zone is referred to as the
<br />main zone since new high pressure zones are being proposed to serve the development areas. Since the
<br />northeast and the northwest study areas have the potential of being annexed to the system's main pressure
<br />zone but not to the low pressure zone, only the main pressure zone was evaluated in this study. The water
<br />serviceability analysis completed for the study areas is summarized in the following sections.
<br />3.1 Existing System Description
<br />The City of Elk River utilizes five (5) production wells to supply water to the system's main pressure zone.
<br />The zone's firm pumping capacity, which is the total pumping capacity with the largest well out of service,
<br />is 3,400 gallons per minute (gpm). Table 3.1 bellow summarizes the main zone's existing well pumping
<br />capacities.
<br />Table 3.1 — Main Pressure Zone Existing Water Supply Capacity
<br />Well Name Well ID Year Depth Status Capacity Capacity
<br />Installed (feet) (gpm) (gpd)
<br />Well 5 537682 1994 406 Active 850 1,224,000
<br />Well 6 580320 1999 300 Active 850 1,224,000
<br />Well 7 664852 2001 341 Active 850 1,224,000
<br />Well 8 694499 2004 390 Active 850 1,224,000
<br />Well 9 757624 2008 454 Active 850 1,224,000
<br />Firm Pumping Capacity 3,400 4,896,000
<br />Total Pumping Capacity 4,250 6,120,000
<br />GPM — Gallons per Minute; GPD — Gallons per Day
<br />Elk River's main pressure zone has three (3) satellite direct filtration water treatment plants to remove iron,
<br />manganese, and other impurities from the groundwater. Table 3.2 bellow summarizes the main zone's
<br />existing treatment facilities. Currently, Well 8 is routed to Well House 9 where it receives chemical
<br />conditioning. This well is does not need physical treatment (filtration) as its water quality meets existing
<br />drinking water standards. The main zone's firm treatment capacity was considered to be 80-percent of the
<br />zone's total treatment capacity to account for filter downtime for backwashes and plant maintenance.
<br />Table 3.2 — Main Pressure Zone Existing Water Treatment Capacity
<br />Plant Wells Total Capacity Firm Capacity
<br />Name Treated Treatment Type
<br />(Jpm) (9pd) (Jpm) (9pd)
<br />5 5 Pressure Filtration 850 1,224,000 680 979,200
<br />6 6 Pressure Filtration 850 1,224,000 680 979,200
<br />7 7, 9 Pressure Filtration 1,700 2,448,000 1,360 1,958,400
<br />N/A 8 Chemical Only 850 1,224,000 850 1,224,000
<br />Treatment Capacity 4,250 6,120,000 3,570 5,140,800
<br />CiNIVI — Ciallons per IVlinute; CiNu — Ciallons per uay
<br />The system's main pressure zone has two (2) water towers. Water towers stabilize water pressure during
<br />average day and peak water demands and provide water storage for fire protection and power outages. At
<br />Feasibility Report
<br />Northeast & Northwest Urban Service Area Expansion Study
<br />City of Elk River, MN
<br />WSB Project No. 020010-000
<br />Page 3
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