Inside one of the largest and least known engineering wonders of California, a race has been under way since late summer.
It’s more than a race to scrape 1 million cu. yds. of mud out of the Yolo Bypass in a two-month window ending in November.
It’s also one with the weather. As sure as California’s summers are hot and endlessly dry, the winter monsoon, from which the bypass was created to protect Central California, is on the way, no matter the contract dates.
And it’s also a bit of an equipment scramble. To find 16 Caterpillar 637 scrapers, the contractor, FCI Constructors, had to go to two companies, Foster and Sons of Fresno, Calif., and Top Grade Contraction of Livermore, Calif. The companies are working directly for FCI on a rental basis with no subcontractors on the job.
The scrapers must move 29,000 cu. yds. (22,172 cu m) of earth every day on a 5 mi. trip onto nearby farmland, said Shawn Golden of FCI Constructors.
FCI Constructors won the California Department of Water Resources (DWR) contract with a $2.8 million bid, working on a time and materials basis. This type of contract is more often used for home improvement than a big state contract.
“It is a little unusual to see that kind of contract from a state agency,” said Golden. “Everything is going smoothly and we expect to finish in November.”
The project is removing sediment deposited in floods in order to increase the carrying capacity of the bypass, said William Hicks of the DWR.
“The contract runs between August 15 and November 15, but the removal work really has to all be done between September 1 and November 1,” said Hicks.
Four feet of mud is being scraped off 250 to 300 acres.
The Yolo Bypass, which is actually an engineered floodplain, resembles a dry river running parallel to the Sacramento River. Summer travelers are sometimes perplexed when they cross the Sacramento River, only to hit a second bridge and to cross a wider, totally dry river planted with farm crops.
The picture is different when high water from winter storms comes, and the bypass often becomes a 3-mi.-wide muddy flood.
The Sacramento River carries the biggest load of Sierra-Nevada runoff from Northern California out through the Delta and under the Golden Gate Bridge.
The 40-mi.-long stretch of land extends from the confluence of the Feather and Sacramento rivers to a point above the city of Rio Vista, where it safely returns the excess flows to the Sacramento River.
The Bypass resulted when early 20th century engineers finally realized that rivers in California could not be contained as they could in the Eastern half of the nation.
Rather than building strong levees to keep the river in the channel, a plan that failed repeatedly in California, a system of weirs, levees and basins was constructed as temporary relief valves for massive deluges.
Most of the bypass system was completed by the early 1930s by the U.S. Army Corps of Engineers. During the summer, the relief canals and holding basins are often farmed.
For 70 years, through massive floods in 1955, 1963, 1986 and 1997 the bypass has worked, but the mud left behind by the floodwaters has reduced its effectiveness.
“What we are doing is going in and taking out sediment from all the floods, to allow it to handle more floodwater,” Golden said.
The Yolo Bypass is one of two such bypass systems constructed north of the Delta.
The Bypass system has become prime habitat for migratory salmon, waterfowl and a variety of shallow water creatures that lost most of their habitat to development.
This environmental sensitivity has made the bypass the centerpiece of restoration by a plethora of wildlife agencies and put restrictions on the construction contract, especially its time frame.
Beyond the fleet of 637 scrapers, FCI is using two Cat 14H blades, one Cat D6R LGP tracked tractor, one Cat D6N LGP tracked tractor, one Cat D6R XL tracked tractor, one Cat 633 scraper with a 10,000 gal. waterpull, one Cat 631 scraper with a 10,000 gal. waterpull and one Cat 621 scraper with a 8,000 gal. waterpull.
Additionally, the site is using GPS to manage the cuts and fills, Golden said.
FCI Constructors is a California subsidiary of Flatiron Inc. of Colorado. Flatiron, which traces its roots back to 1947, is wholly owned by the Netherlands-based Royal BAM Group.
The company has many Northern California contracts, including the ongoing $1 billion San Francisco-Oakland Bay Bridge. CEG