Item 5: Resolution Adopting Amended SDC Methodologies and Rates

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other parameter not represented by BOD or 1SS such as screenings, grit, or pathogens? These questions are answered by the functional performance component. The design basis co~~ders what system capacity parameter or combination of parameters drives the sizing of the facility and, therefore; the constructed cost. The allocation basis for each,facility , component presented in. Table 3 combines both the functional performance and design basis considerations. In addition. to these system parameters, because there can be proj-ec:;ts'that provide overall support-for the wastewater system, a separate catego~ of lIindirect" , support facilities is used to provide for reallocation of these support-type, costs across all of the system capacity parameters. ' TABLE 3 Summary of Facility Process Component Allocation to System Capacity Parameters System Capacity 'Parameter Average Peak Facility Process Component Flow Flow BOD TSS Indirect Total Collection system pipeline % ~ 1 Collection system pump stations % ~ 1 Preliminary treatment % ~. 1 Primary treatment % % % '1 Secon~ary treatment % % % 1 Disinfection/outfall % ~ l' , Biosolids (same for all three subcomponents) % % - 1 Tertiary fjlters % % % 1 Reuse ,facilities 1 1 Odor control % % 1 Peak flow management 1 1 Support facilities (Indirects) 1 1 Step Two · ,Growth Capacity Requirements In developing SDCs, costs related..to growth (see 'Cost Basis' below) ,are spread over , growth's total ,capacity requirements over the study period to determine the overall cost per unit of growth by capacity measure. The, study period is defiited asa 20-year period, consistent with facility planning requirements. The Department of Environmental Quality (DEQ) stipulates that entities that own and operate wastewater facilities assume a 20-year pla.mUng horizon when developing facility plans (see DEQ Guidance for Development of Wastewater Facilities Plans, 20(0). To determine the capacity required by growth, the capacity required by exi~ting users is subtracted from the capac;ity projected in the facility plan to be required at the end of the planning period. For peak flow estimates, existing users' current capacity requirements are adjusted for anticipated III reductions (see Guidelines for the Preparation of Facilities PlanS and Environmental Reports for Community Wastewater Projects, 1999).