Orestimba Creek Feasibility Study - Stanislaus County

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Economics Appendix – Draft Report - Orestimba Creek Feasibility Study, Stanislaus County, California – September 2012 Orestimba do not capture the total potential loss, these non-quantified losses are an incrementally-small portion of the overall losses and would not change the feasibility or formulation of any of the alternatives. Potential traffic delays and temporary interruption in public services were also not quantified. State Highway 33 runs through the study area and may be closed shortly (a few days) from flooding along Orestimba Creek. Minor roads within the flood plain may also be closed for short durations due to flooding, but like Highway 33, alternate routes would not add significant time loss or additional resource consumption to the NED account. Because of the short durations and light normal traffic, losses for any traffic disruption that may occur were not analyzed. Other non-monetary risks could also occur from a flood event but are not included in the NED evaluation. General reductions in risks to health, safety and public welfare are typically associated with flood conditions and are further reasons why flood protection serves the federal interest and the public good. Within the Orestimba Creek floodplain there are some public structures that could result in a loss of public services due to flooding at least one-foot above the first floor, but would not significantly impact plan formulation. 44
Economics Appendix – Draft Report - Orestimba Creek Feasibility Study, Stanislaus County, California – September 2012 7.0 Benefit-Cost Analysis 7.1 Annual Costs With benefits calculations complete, annual costs need to be derived to complete the benefit cost analysis. Economic feasibility and project efficiency are determined through benefit cost analysis. For a project or increment to be feasible, benefits must exceed costs and the most efficient alternative is the one that maximizes net benefits (annual benefits minus annual costs). For the benefit-cost analysis, these project costs need to be described in terms of annual costs. The project costs were amortized over the 50-year period of analysis using the current federal discount rate of 4%. Interest during construction was based on a 2 year construction schedule from 2015 to 2017 assuming uniform expenditure over the construction period. Detailed and itemized costs for the alternatives can be found in the Cost Appendix. Operation, Maintenance, Rehabilitation, Remediation and Repair (OMRR&R) were added for the total annual costs for each alternative. 7.2 Net Benefits 7.2.1 The NED Plan With the Channel Modifications increment dropping from the Federal Interest, the optimized Chevron Levee becomes the NED Plan. This levee would be about 4-5 feet tall, depending on ground elevation changes along the levee alignment. 7.2.2 The Tentatively Recommended Plan The only difference between the Tentatively Recommended Plan and the NED Plan is the height of the chevron levee. The height of the chevron levee for the local plan must meet State of California requirements (per Senate Bill 5) of being at least 3 feet above the with-project mean 0.5% (1/200) WSEL. This levee would be about 6-7 feet tall or approximately 2 feet taller than the federal interest levee. 7.2.3 Benefits and Costs A more rigorous and detailed MCACES cost estimate was performed for the NED Chevron Levee and the LPP (Alternatives 2 and 3 respectively). Benefits and costs for these alternatives are provided in Table 7-1 below. 45
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Orestimba Creek Feasibility Study - Stanislaus County

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