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129 <br /> CommunitySmall 1 1 Construction 1 <br /> For example,there is a$73,500 difference in present worth cost associated with a 100-unit development that installs all of the collection system <br /> equipment up-front(Figure 8,Option 2)compared to installing ten (10)systems per year over the next ten (10)years(Figure 8, Option 1).This <br /> assumes on-lot equipment at$5,000/connection and 3% interest.The user rate savings are$3.12/month/connection less than if the system <br /> were constructed entirely at the outset,assuming 3% interest and a 30-year term. <br /> 1 2 3 4 5 6 7 8 9 10 0 <br /> A=$54,000 <br /> N=10 PW—$500,000 <br /> 1=3% <br /> PAY=$426,50fl <br /> Option 1 Option 2 <br /> Figure 8.Economics of phasing in an Orenco Effluent Sewer system. <br /> Life Cycle Costs <br /> Virtually all wastewater collection and treatment system owners will spend more on operation and maintenance than on the initial capital cost of <br /> the system.Consequently,when evaluating collection system options or establishing user rates,a thorough understanding of operation and main- <br /> tenance costs is critical. <br /> Until recently,operation and maintenance costs of alternative collection systems weren't substantiated with long-term data.As reported in <br /> "Operational Costs of Two Pressure Sewer Technologies:Effluent(STEP)Sewers and Grinder Sewers,"the uniform equivalent monthly costs for <br /> effluent sewers(Orenco) and grinder sewers are$7.05/month/EDU and$16.91/month/EDU, respectively(Molatore, p.12). Moreover,the effluent <br /> sewer cost includes solids management and the grinder system cost does not. <br /> Lacey,Washington has a hybrid collection system consisting of 12,000 gravity sewer connections—with 47 lift stations and 152 miles(244 km) <br /> of mainlines—3,000 effluent sewer connections,and 102 grinder pump connections. In a paper presented at WEFTEC 2013,Orenco's Bill Cagle <br /> et al concluded that,"With substantially lower up-front capital and repair/replacement costs,and with 0&M costs that are virtually the same as <br /> those of gravity sewers,the life cycle costs of Lacey's STEP [effluent] sewer are clearly lower than those of a typical gravity sewer"(Cagle et al, <br /> P-1). <br /> Based on data listed in Table 14,the average difference in cost between an Orenco Effluent Sewer($9,702/connection)and a gravity sewer <br /> ($16,394/connection) is$6,692. If the average difference in cost(between gravity sewers and Orenco Effluent Sewers)were financed over 30 <br /> years at 3% interest,the monthly debt retirement cost per connection would be$28.44—an insurmountable deficit to overcome,even with the <br /> perceived lower operation and maintenance costs of gravity sewers. <br /> Additional Resources <br /> In 2010 the Water Environment Research Foundation (WERF)developed fact sheets for gravity sewers,effluent sewers,grinder sewers,and <br /> vacuum sewers.The fact sheets include design characteristics, performance,and costs for each collection system technology.A Wastewater <br /> Planning Model (cost estimating tool) is also available that allows users to compare capital and life cycle costs of effluent sewers to those of <br /> grinder,vacuum,and gravity sewers.10 An example for a 200-unit subdivision is shown in the following tables.WERF's results generally show that <br /> effluent sewers are the lowest cost alternative,with respect to up-front and life cycle costs. <br /> ©2014 Orenco Systems®Inc. NFS-EFS-CC-1 <br /> Rev.1.6,©08/14 <br /> Page 11 of 13 <br />