Sacramento levee fixes: A year of progress

Published Dec. 2, 2013
U.S. Army Corps of Engineers Sacramento District levee work is underway Aug. 21, 2013 along the north bank of the American River, just east of its confluence with the Natomas East Main Drainage Canal in north Sacramento, Calif. Complicating the project to install 3,300 linear feet of seepage wall in the levee are land easement rights, an inactive railroad line and an assortment of buried utilities that obstructed the Corps’ work near here more than a decade ago

U.S. Army Corps of Engineers Sacramento District levee work is underway Aug. 21, 2013 along the north bank of the American River, just east of its confluence with the Natomas East Main Drainage Canal in north Sacramento, Calif. Complicating the project to install 3,300 linear feet of seepage wall in the levee are land easement rights, an inactive railroad line and an assortment of buried utilities that obstructed the Corps’ work near here more than a decade ago

A contractor for the U.S. Army Corps of Engineers Sacramento District inspects a newly-drilled hole on the Watt Avenue bridge in Sacramento Calif., July 25, 2013. Holes across the bridge provide access to the levee beneath, where crews will install a seepage cutoff wall.

A contractor for the U.S. Army Corps of Engineers Sacramento District inspects a newly-drilled hole on the Watt Avenue bridge in Sacramento Calif., July 25, 2013. Holes across the bridge provide access to the levee beneath, where crews will install a seepage cutoff wall.

U.S. Army Corps of Engineers construction crews use wooden planks to help a jet-grout drill cross a closed portion of Watt Avenue bridge in Sacramento, Calif., Aug. 15, 2013. Corps representatives, the project contractor and the California Highway Patrol closed three lanes of traffic during non-commute hours in order to drill through the bridge to access the levee.

U.S. Army Corps of Engineers construction crews use wooden planks to help a jet-grout drill cross a closed portion of Watt Avenue bridge in Sacramento, Calif., Aug. 15, 2013. Corps representatives, the project contractor and the California Highway Patrol closed three lanes of traffic during non-commute hours in order to drill through the bridge to access the levee.

Work continues Oct. 2, 2013, on 3,300 feet of seepage cutoff wall along the north bank of the American River in north Sacramento, Calif. Completion is targeted for mid-October. Construction crews for the U.S. Army Corps of Engineers Sacramento District are helping ensure the levee's height and slope will be brought back to pre-construction levels by November 1 – in time for the rainy season.

Work continues Oct. 2, 2013, on 3,300 feet of seepage cutoff wall along the north bank of the American River in north Sacramento, Calif. Completion is targeted for mid-October. Construction crews for the U.S. Army Corps of Engineers Sacramento District are helping ensure the levee's height and slope will be brought back to pre-construction levels by November 1 – in time for the rainy season.

SACRAMENTO, Calif. - Sacramento is among the most at-risk cities in America for catastrophic flooding. An aging system of dams, weirs, bypasses and levees work together to reduce flood risk for the city. But that system, just like a chain, is only as strong as its weakest link, and needs comprehensive modernization.

This year, the U.S. Army Corps of Engineers Sacramento District continued to make progress strengthening those links by fixing gaps in seepage cutoff walls in the lower American River's levees. The Corps built more than 20 miles of seepage cutoff walls into American River levees a decade ago, but work was set aside for later—leaving gaps—where complicated encroachments exist such as utilities, power lines and bridges. Only a handful of these complex gap sites remain, with final construction slated to wrap up in 2016.

By the close of 2013, the district will have completed three more construction projects this season under its American River Common Features program, a joint effort between the Corps, the state’s Central Valley Flood Protection Board and the Sacramento Area Flood Control Agency to reduce flood risk for Sacramento.

One of the fixes required building a seepage wall beneath one of Sacramento’s busiest thoroughfare, the Watt Avenue bridge. Crews worked through the night to minimize traffic disruption, and with the help of California Highway Patrol, temporarily closed up to three lanes at a time so they could maneuver the drill-rig back and forth across the bridge. To install the wall, crews cut holes in the bridge and then lowered the drill through the holes to reach the levee underneath. Using this jet grout method, the drill injects cement-like slurry into the bore holes, forming columns in the levee. In all, 40 columns of grout were installed side-by-side inside the levee to form a continuous barrier against seepage, with a dozen of those columns directly beneath the Watt Avenue bridge.

This same jet grout method and contractor were also tapped for $3.9 million of similar work inside the E.A. Fairbairn Water Treatment Plant, adjacent to California State University-Sacramento. Here several water intake structures, various utilities and a sewer line obstructed conventional seepage cutoff wall construction between 2000 and 2002. This year's jet grout construction at two levee sites inside the plant’s grounds is expected to be complete in January.

The third project scheduled for completion in 2013 was a $3.9 million levee project along the north bank of the American River, just east of its confluence with the Natomas East Main Drainage Canal in north Sacramento. This section, called NEMDC south, was complicated by buried utilities and an inactive railroad line. The district completed construction of 3,300 linear feet of seepage cutoff wall in October. In the coming years, two nearby smaller sections, called NEMDC north and the NEMDC extension, are in line for similar construction.

Two sites originally scheduled for 2013 are now scheduled to be completed in 2014. Fixing these lower American River levee gaps, one in Carmichael and the other in the River Park neighborhood, will complete the construction contracts awarded in September 2012, totaling more than $16.2 million.

While construction of cutoff walls in American River levees is nearly complete, and has already greatly reduced the risk of seepage, much work remains to be done in Sacramento to modernize its flood control infrastructure. The district is also working to complete a comprehensive study that investigates improvements to the flood risk reduction system throughout the city called the American River Common Features General Re-evaluation Report. A draft report, along with a recommended plan for improvements, is scheduled to be released for public comment in 2014.