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AFFORDABLE <br /> r St ii i ,a t x t, <br /> 1„ �.,.'3I,H II.Ii li ,„ qW� � ott1'e' is t §oi o i,4fio ' u�79 <br /> dl lit lt(IIi l f7 ll Illy. ii <br /> Berulse the city wanted to keep seNVer rates as]ow as possible,life- Marko i <br /> cycle and operating costs were It critical factor in the city's technology <br /> selection process.With some technologies,life-cycle costs contribute a <br /> large portion,often the majority,of the users'rate structure. <br /> Like other small communities,Yehn was initially concerned about two <br /> O&M cost categories:the cost of periodically pumping and hauling <br /> solids from septic tanks,and the cost of replacing t'he system's in-tank <br /> pumps.Yelin's experience has shown these casts are not often incurred <br /> and are therefore very low,amortized on a per-month basis. <br /> For example,the NPDF.S permit requires each on-lot system to be <br /> inspected every three years.Sludge and scum levels in the tank are <br /> measured said recorded,the pump is inspected,and the effluent screen <br /> is cleaned,Most residential units have 1,000-gallon tanks,which are <br /> pumped out every 5.91 years on average,at a cost of$0.24 per gallon. <br /> Amortized without interest this comes to about 8 her month np, <br /> residence to manage sludge <br /> To minimize the cost of replacing pumps,Yelm selected an Orenco <br /> Biombe`r STEP package for each tank,which includes an Orenco high- <br /> head effluent pump.The system was commissioned in 1994,and more <br /> than 1,700 STEP systems have been installed.Iet only 28 pumps have <br /> been reohced n die nterim. Since the pumps are estimated to last <br /> 20 years,and pump replacement only costs$600(including labor and <br /> materials),tile monthly cost of each hOu&el'hold's pump,amortized <br /> without interest,is only$2.50. <br /> As a result of these low operation and maintenance costs,Yelm's <br /> residents pay only$43.16 in monthly sewer rates. <br /> One important side note: When the town's system was designed, <br /> Yelm;s consulting engineering firm,Skillings Connolly,designed into <br /> the system an 8-acre wetland park for wastewater reuse and aquifer <br /> recharge This was the first Class A Water Reclamation Facility ever <br /> constructed in the state of Washington,and Yelms'treated effluent has For more information Sewers <br /> about <br /> since been used in fire hydrants and to irrigate schools, Orenco Effluent Sem�ers and <br /> g parks,and <br /> I AdvanT'ex'Treatment Systems, <br /> contact Orenco Systems',Inc.,at <br /> 800-348-9843. <br /> _gy�pp <br /> 0.—Syetams" <br /> t—par W <br /> it'firNGx,i�rnwra <br /> 800-348-9843.541-459.4449 <br /> www.orenco.com <br /> ©2009 Orenco Systems"Inc. <br /> NCS7 <br /> 10ro9 <br /> Page 2.12 <br />