Orestimba Creek Feasibility Study - Stanislaus County

Economics Appendix – Draft Report - Orestimba Creek Feasibility Study, Stanislaus County, California – September 2012
Table E- 5: Optimization of the Chevron Levee Height at Stuhr Rd and CCID Canal
Crossing
Return
Period
Levee
Elevation (ft.)
*Annual Benefits
($1,000's)
*Annual Costs
($1,000's)
*Net Benefits
($1,000's)
1/50 111.21 6,079 749 5,330
111.25 6,188 753 5,435
111.5 6,412 777 5,636
111.75 6,612 800 5,812
1/500 112 6,785 823 5,962
112.25 6,910 847 6,063
112.5 6,990 870 6,120
112.75 7,035 893 6,142
113 7,056 917 6,139
113.25 7,064 940 6,124
113.5 7,066 964 6,103
113.75 7,067 987 6,080
114 7,067 1,010 6,057
114.25 7,067 1,034 6,034
1/200+3ft 114.8 7,067 1,085 5,982
* The Benefits and Costs shown here are different than those presented in Chapter 3 of the main report,
because these show the actual values used for the sensitivity, while the main report has adjusted those
values to reflect total project benefits and costs. Annual Benefits, Annual Costs and Net Benefits shown
here do not reflect actual benefits and total costs used for final net benefit and BCR calculations. The
index point used for this height optimization exercise is different from the one used for economic
justification. Benefits and costs used for economic justification can be found in Table E- 10. More
information about different index points and the effect on damages in this study area is available upon
request.
Sensitivity analysis was performed on other index locations along the levee alignment and the
results were within 0.2ft, which is well within the error bands of the ground elevations. The
optimized height is approximately 1.5ft above the existing 2% (1/50) WSEL, which is reasonable
for an alluvial fan floodplain given uncertainty in ground elevations and stages.
ES-x