Item 5: Resolution Modifying Stormwater SDC

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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 6.406 Eugene code, 1971 as "any hard surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from conditions pre-existing to development. Common impervious surfaces include, but are not limited to, rooftops, walkways, driveways, parking lots, or concrete or asphalt surfaces." The estimated non-assessable cost of the system-wide capacity from future capacity-enhancing projects, as contained in the Stormwater SOC-Eligible Project List, and the estimated available capacity in the existing stormwater system projected to be used by new development is used as the basis for determining the stormwater SOC. The stormwater SOC is comprised of an improvement fee and a reimbursement fee, as new development will require the construction of additional system capacity as well as the use of available capacity in the existing system. The per unit cost of additional capacity for the improvement fee is based on the value of the system-wide capacity of future capacity- enhancing projects (current planned projects are listed in the Stormwater SOC-Eligible Project List, Table 10) divided by the total projected impervious surface area that will be added by new development at build-out within the Urban Growth Boundary (UGB). The per unit cost of existing capacity for the reimbursement fee is based on the value of available system-wide capacity within the existing system projected to be used by new development divided by the total projected impervious surface area that will be added by new development at build-out within the UGB. The value of the future stormwater system is based on the estimated costs of planned future capacity-enhancing stormwater projects contained within stormwater plans and the Capital Improvement Plan (CIP). Of that total value, the SOC-eligible component is attributable to those portions of future projects that are non-assessable and capacity-enhancing and related to the demands of future development; Le. add new capacity for new users. The total value of the existing system is estimated based on the replacement cost of the stormwater system components, which include both piped system and open channel system components. Assessable costs are excluded from the SOC-eligible existing system costs. Assessable costs are determined using the approach specified in the City Code. The city assesses up to and including the first 24 inches of pipe diameter or equivalent capacity. The non-assessable portion of stormwater system costs (SOC eligible costs) is based on replacement costs minus assessable costs. The portion of non-assessable existing system value allocated to new development (SOC-eligible value) is established by determining the percent of piped system and open channel system capacity projected to be used by new development. The use of capacity of the existing system is estimated with use of hydraulic modeling to identify existing available capacity (based on existing land use and flow data) and expected future conditions (based on Metro Plan designations).