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2.4 Wastewater Flows
<br /> 2.4.1. Historical Flows
<br /> The Elk River Wastewater Treatment Facility (WWTF) records flows to the facility by a
<br /> parshall flume. The daily total values are recorded each day along with precipitation
<br /> received on Discharge Monitoring Reports (DMR). These recorded flows are used to
<br /> evaluate current flow trends and develop future flow projections.
<br /> A summary of average daily and monthly flows to the WWTF for 2006 to 2011 are
<br /> presented in Table 2.2. The historical flow variation data is shown in Figure 2.4. Average
<br /> yearly flows vary significantly during this period showing seasonal affects. Average
<br /> monthly flows spike briefly during spring and summer months each year. This type of
<br /> flow pattern indicates inflow and infiltration (I & I) into the collection system. I & I flows
<br /> are heavily influenced by seasonal and precipitation events and are present in essentially all
<br /> gravity collection systems.
<br /> From the observed historical data, the Average Dry Weather (ADW) flow is 1.142 MGD
<br /> and the Average Wet Weather (AWW) flow is 1.302 MGD yielding an AWW/ADW ratio
<br /> of 1.14.
<br /> Table 2.2
<br /> Average Daily Flows
<br /> Elk River Wastewater Treatment Facility
<br /> Monthly
<br /> 2006 2007 2008 2009 2010 2011 Average
<br /> Month (gallons) (gallons) (gallons) (gallons) (gallons) (gallons) (gallons)
<br /> January 1,532,516 1,190,516 1,204,903 1,214,065 1,222,903 1,200,323 1,260,871
<br /> February 1,329,286 1,193,286 1,209,897 1,176,214 1,215,536 1,195,000 1,219,870
<br /> March 1,310,645 1,166,516 1,216,581 1,346,774 1,199,129 1,225,484 1,251,688
<br /> April 1,019,000 1,173,133 1,291,500 1,506,767 1,176,067 1,181,000 1,224,578
<br /> May 1,116,774 1,162,258 1,249,774 1,454,387 1,158,032 1,223,548 1,227,462
<br /> June 1,071,533 1,189,867 1,239,367 1,236,167 1,206,933 1,206,333 1,191,700
<br /> July 1,116,774 1,161,677 1,162,806 1,126,903 1,190,677 1,244,226 1,167,177
<br /> August 986,097 1,179,806 1,165,194 1,137,677 1,190,677 1,275,355 1,155,801
<br /> September 1,014,367 1,186,667 1,196,267 1,183,700 1,194,367 1,198,367 1,162,289
<br /> October 1,040,935 1,216,000 1,173,226 1,187,516 1,166,032 1,147,419 1,155,188
<br /> November 1,057,367 1,190,967 1,152,700 1,155,667 1,188,433 1,117,733 1,143,811
<br /> December 1,113,839 1,188,839 1,226,226 1,191,097 1,159,032 1,112,968 1,165,333
<br /> Yearly Average 1,142,428 1,183,294 1,211,120 1,243,078 1,188,985 1,193,980 1,193,814
<br /> City of Elk River—T12.104758 Page 4
<br /> Wastewater Treatment Facility Plan Prepared by Bolton&Menk,Inc.
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