Orestimba Creek Feasibility Study - Stanislaus County

Economics Appendix – Draft Report - Orestimba Creek Feasibility Study, Stanislaus County, California – September 2012
determined that the Farm Rd alternative was more economically efficient than a Stuhr Rd option.
The interceptor channel was also removed as it did not provide a positive incremental net benefit.
The team decided to move forward into the final array with the following 3 alternatives:
1. No Action Plan
2. Chevron Levee: Chevron levee at optimized height (TOL elevation of 112.75 feet. (Alts
7-9 in Table 6-1).
3. Local Plan: Chevron Levee set at a height equal to the mean 0.5% (1/200) WSEL + 3
Feet; TOL elevation of 114.8 feet. (Not listed in Table 6-1)
These alternatives were analyzed in more detail using updated hydraulic floodplain modeling,
economic modeling and costs. A map showing the locations for the chevron levee and channel
modifications (which dropped out) are shown in Figure 6-1 above. For a more detailed
description of these alternatives, please see the main report.
6.3 Annual Benefits for the Final Array of Alternatives
The mean annual benefits for the final 3 alternatives can be found by Economic Impact Area in
the tables below. Note that there is no incremental benefit for the Local Plan because the
incrementally higher levee height does not provide an additional measurable benefit to the city of
Newman and is mainly to comply with State of California requirements Senate Bill 5
requirements for urban and urbanizing areas.
Residual Damage in the Urban EIA with the Chevron Levee in place consist of existing storm
drainage damages caused by rain events above a 10% (1/10) annual chance frequency.
It’s noted that the damages/benefits for the final array are higher than those reported in the 2009
screening phase (Table 6-1). This increase is mainly due to an updated hydraulic model in which
flooding happens slightly more frequently and shows flooding occurring in areas of Newman
that were not previously flooded during the screening phase.
Table 6-4: Annual Benefits – The Final Array – Rural EIA
October 2011 Prices ($1,000’s), 4% Interest Rate
Alternative Annual Damages Annual Benefits Incremental Benefits
1. No Action 2,284 0 0
2. Chevron Levee at
112.75ft
3. Chevron Levee at
114.8ft
2,085 198 198
2,085 198 0
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