Natomas Levee Improvement Program - SAFCA

SAFCA’s estimate for fish and wildlife facilities in Reach A is substantially larger than
the USACE estimate. The basis for this difference is unclear.
3.1.2 Levees and Floodwalls
SAFCA’s estimates for levee and floodwall construction in Reach A are based on the
design consultant’s opinion of probable cost. These costs are significantly higher than the
unit prices for levee and floodwall construction actually incurred in Reaches B and C.
The SAFCA estimates assume that levee, seepage berm and irrigation canal construction
in this reach will require approximately 1.5 million cubic yards of borrow material. The
Borrow Royalty/Land cost is approximately $10.7 million. This includes the cost of
acquiring 280 acres of land south of Fisherman’s Lake which will serve as the primary
source of this material and the cost of obtaining the right to take a small amount of
surplus material from the Twin Rivers School District site along the Natomas East Main
Drainage Canal (NEMDC) near Elkhorn Boulevard.
The USACE estimate for levee and floodwall construction in Reach A is about 40 percent
higher than the SAFCA estimate. This difference reflects USACE’s higher unit costs for
borrow activities and cutoff wall construction. In addition, the USACE estimate assumes
that the landside slope of the levee adjacent to the urban subdivisions in the lower portion
of Reach A will be flattened to achieve a 3:1 slope. USACE also assumes that a 15-foot
maintenance corridor will be added at the landside toe of the expanded levee. The
SAFCA estimate assumes that the top of the levee in this area will be degraded prior to
cutoff wall installation and then the levee will also be reconstructed to a 3:1 slope. The
USACE estimate includes a 32 percent contingency compared to the 30 percent
contingency on the levee improvements and borrow site development costs and a 10
percent contingency on the land required for borrow used in the SAFCA estimate.
3.1.3 Interior Drainage Pumping Plants
RD 1000’s largest drainage pumping facilities, Pumping Plants 1A and 1B, and the City
of Sacramento’s Sump 160 will need to be reconstructed to accommodate the 200-year
project in Reach A. SAFCA’s estimate of the cost of this work reflects the design
consultant’s opinion of probable cost based on a 30 percent design plus a 30 percent
contingency.
The USACE estimate for this reconstruction work is much lower than SAFCA’s estimate,
however the basis for this difference is unclear.
3.1.4 Lands & Damages
A substantial amount of agricultural and rural residential land will be needed to
accommodate the levee improvements planned for Reach A as well as the relocation of
the Riverside Irrigation Canal in this reach. SAFCA’s estimate of the cost of this land
reflects the range of the actual costs incurred for agricultural and rural residential land
elsewhere in the Natomas Basin and includes a 10 percent contingency.
SAFCA’s estimate also includes costs for lands and damages administration that
represent about 38 percent of the value of the land to be acquired.
The USACE estimate for lands and damages including administration is about the same
as SAFCA’s estimate.
8