Resolution No. 4740 - Laserfiche WebLink

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METHODOLOGY: City of Eugene Systems Development Charges Appendix D Stormwater System Charge Detail 1.0 Formula The impact analysis for the stormwater system is based on square footage of impervious surface which creates an impact on the stormwater system by land use type. Impervious surface is defined in Section 7.275, Eugene code, 1971 as "earth surface made impervious by development to vertical downward penetration by water". Impervious surfaces typically consist of concrete, asphalt and roofing materials. The impervious surface of a residential unit is usually the roof, sidewalks, driveway and any patio areas. The cost of the existing stormwater system is used as the basis for determining the Stormwater SDC. The stormwater SDC is an improvement fee, as new development will require the construction of additional system capacity. The per unit cost of additional capacity is based on existing system replacement value divided by impervious surface area. The total value of the system is estimated based on the replacement cost of the stormwater system components which include miles of pipe and drainage channels, stormwater cleanouts, catch basins, inlets/outlets, and manholes. For current total value (Total Replacement Cost) of the stormwater system, see Table 12. Assessable costs were calculated using the approach specified in the City Code. The city assesses up to and including the first 24 inches of pipe diameter and in excess of 60 inches. For pipe over 24 inches in diameter, the city pays a proportion of the cost. The non-assessable portion of stormwater system costs (SDC eligible costs) is based on replacement costs, minus assessable costs. Table 12 provides a detailed breakdown of the calculation and numerical supporting data of the stormwater SDC. Figure 6 illustrates the calculation formula of the stormwater SDC. The stormwater SDC rates per unit of capacity can be found in Appendix F in the current adopted SDC fee schedule. To determine a cost per square foot of impervious surface, the non-assessable portion (SDC eligible costs) of the stormwater system cost was first divided by the total impervious acres within the city limits. The total impervious surface calculated for each development is assumed to contribute to the public stormwater system. The number of acres of impervious surface in each type of land use was determined using runoff coefficients currently employed by the city. The cost per impervious acre is estimated based on dividing the non-assessable costs (eligible SDC Costs) by the total number of acres of impervious surface in the city limits. The cost for a square foot of impervious surface is calculated by dividing the cost per acre of impervious surface by the number of square feet in an acre (43,560). City of Eugene SDC Methodology Stormwater, Page 0- 1