Project: American River Common Features 96/99
What does it do? The Common Features project was designed to strengthen the American River levees so they can safely pass a flow of 160,000 cubic feet per second(cfs).
Features: The Common Features project has installed roughly 23 miles of slurry wall up to depths of 80-feet, raised levees to provide adequate freeboard, addressed slope stability issues and corrected some erosion problems.
Construction Schedule: The majority of levee work along the American River has been completed. There are several reaches of levee that need some work and the work schedule for those pieces are as follows
Mayhew Levee upstream of the Mayhew Drain: The levee improvement portion of the project was completed in 2008. This consisted of installing a slurrywall in the levee, raising the levee by three feet, and widening the top of the levee. Construction of the Closure Structure across the Mayhew Drain will be accomplished in 2009. The purpose of the Closure Structure in the Mayhew Drain is to prevent the American River from backing up into the drain.
North Levee upstream of Watt Ave (Jacobs Lane): A portion of this project was completed in 2008, with the remainder slated for completion this summer. The work consists of reshaping the levee in spots and increasing the height of the levee up to a foot.
Chicken Ranch/Strong Ranch Slough Outfall: Summer 2009 – Strengthening the concrete along the outfall from the pump station to the river.
North Levee Raise Upstream of Howe Avenue: Summer 2009 – Raise the levee up to a foot in height for about 4000-feet.
North Levee Strengthening between NEMDC and Business 80: Summer 2010 - Strengthen levee in this reach through reshaping the levee and providing more stable levee slopes.
“Remaining Sites”: Summer 2009/2010 - There are approximately 18 locations in the levee that do not have a slurrywall in them due to conflict with existing infrastructure. While the levee can safely withstand the 100-year event it may not be able to protect against the design flow of 160,000 cfs. These sites are being evaluated to see if remediation is required. Four projects are scheduled for construction during the summer of 2009, as follows:
Site R-5 and R-6 - Two sites along the right bank of the American River, between Northrop Avenue and Howe Ave.
Site L-12 - A site along the left bank of the American River, near Glenbrook Park .
Cost: Current Authorization is $250 million for the overall project
Project: Common Features General Re-evaluation Report (GRR)
What does it do? The GRR will investigate the flood protection system along the American River, Natomas, the east side of the Sacramento River, and the levees in North Sacramento to identify what improvements are needed to bring the system up to a 200-year standard.
Features: The study will look at options in meeting the 200-year standard.
Construction Schedule: The GRR is planned for completion in December 2010. Construction associated with the report will start approximately a year after adoption of the report by Congress.
Cost: Unknown at this time but will be developed as part of the GRR
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May 2009 Environmental Document
§ Draft Enviromental Assessment Initial Study American River Common Features -Phase 1 §
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