Initial Pipeline Phase Finishes Early

Steel Shoring Box Shaves Several Months From Schedule

A 3-mi. segment of a 13-mi.-long pipeline system underway for the Orange County Water District was completed nearly one year early due to a variety of factors. The work is part of a $486.9 million upgrade to the district's ground-replenishment system. The pipeline will carry 72 million gallons of water a day from a purification plant in Fountain Valley to settling basins in Anaheim.

By Kathy Lee Scott

An ingenious safety device, the elimination of pre-excavation soil stabilization, and the ability to work during the rainy season, allowed general contractor Ken Thompson Inc. of Torrance to finish a 3-mi. portion of a 13-mi. water pipeline for the Orange County Water District in June, almost one year early.

"We employed a unique method of shoring up the trench that reduced cave-ins," said Dan Deming, executive vice president of Ken Thompson. "We used a giant, horizontal system, essentially a safety box, into which the pipe and crew fit."

Crews for Ken Thompson Construction work underneath Interstate 405 at Euclid Avenue in Fountain Valley (photo by Kathy Lee Scott).

The all-steel, 61,000-lb. box was specially constructed for the job by Mike's Welding of Fontana.

"The shoring shields are 10 ft. high and 54-ft. long, and they open at the top and bottom with 7-ft. spreader bars across the top," said Mike Bokulic Jr., vice president of Mike's Welding.

An excavator pulls the shields with the crew inside.

The pipeline is part of a $486.9-million ground-replenishment project approved by the water district in 2001. It includes a new, $292-million water purification plant and new $13-million barrier wells that will hold back seawater from contaminating the underground aquifer. The plant will produce initially 70,000 acre ft. of potable water per year, with a potential annual production of 100,000 acre ft.

J.F. Shea Construction Inc. of Walnut is the general contractor and expects to finish in August 2007. The barrier wells should be finished by June 2006.

The 3-mi. pipeline section is only one of two sections that Ken Thompson is constructing for the OCWD. The general contractor won two bids worth almost $43.7 million on the pipeline project, and Corona-based Colich Construction Inc. won the third, a 4-mi. segment that is worth $16.9 million. Thompson's second segment is 6-mi. long.

Pipeline Runs From Fountain Valley to Anaheim

The 13-mi. water pipeline begins in Fountain Valley, then follows the Santa Ana River flood control channel north to two settling basins in Anaheim. Along its length, the pipeline trenches range in depth from 11 ft. to 30 ft., said Shivaji Deshmukh, assistant director of engineering for OCWD.

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It tunnels under the five major freeways in Orange County and sits within the western levee of the flood control channel for 12 of its 13 mi. Just south of State Route 91, the pipeline branches north from the Santa Ana River to the OCWD-owned Carbon Canyon Diversion Channel before ending at the Miller and Kraemer settling basins on Miraloma Avenue. There, it dumps its water load that then percolates through the soil into the groundwater.

At its start, the pipeline's diameter is 78 in. It then decreases incrementally to its final diameter of 60 in. at its end. The pipeline will carry 72 million gallons a day, or 70,000 acre-ft., to the retarding basins. One acre ft., or 326,000 gallons, will cover a football field to 1 ft.; that quantity provides enough water to two families for a year.

The water source is secondary treated sewage water from one of Orange County Sanitation District's two treatment plants in Fountain Valley; the fluid will be sent through the purification plant, then the pristine water will be pumped north to Kraemer and Miller basins to trickle down to the groundwater.

"It will give us water when we need it and not when the Metropolitan Water District has surplus to sell," said OCWD spokesperson Ron Wildermuth.

Of its 500,000-acre-ft. annual supply, the water district buys about 25 percent from Los Angeles-based Metropolitan Water District of Southern California throughout the year, and withdraws 75 percent from its underground aquifers. Once the project is complete, the district will have a reliable source of drinking water for its 2.3 million customers, Wildermuth said.

Early Completion Saves District $350,000

Welder from Colich Construction works on a 4-mi. segment of 66-in. pipeline alongside Chapman Avenue west of State Route 57 and within the west levee of the Santa Ana River (photo by Kathy Lee Scott).

Construction on the northern 3-mi. portion of the water pipeline began in October 2003. "We didn't get any bonus for finishing early," Thompson's Deming said.

However, the water district saved about $350,000 from its budgeted $17.8 million for this portion of the pipeline project because of the early completion.

"We eliminated the requirement of stabilizing the soil before boring," said Deshmukh, based on the contractor's recommendation.

Another factor in the early finish was an agreement struck by OCWD and the U.S. Army Corps of Engineers, which regulates activity around the flood control channel. "They allowed us to work in winter as long as the water flows in the river were under 5,000 csf (cubic feet per second)," said Mike Markus, project manager for OCWD.

"We'd wait for the rain to stop, then went to work," Deming said. "The rain just drained from the sandy ground," he added.

Tunneling displaced lots of sandy, river-bottom soil, which the contractor sold to ready-mix companies. With permission, it also spread some soil in nearby ponds and depressions, Deming said.

The majority of the work was done before the winter rains came, and because the water district owned part of the land on which the northern section of the pipeline is situated, it could control the work schedule, Deshmukh said.

"The biggest factor (for early completion) was the district's cooperation," Deming said. It didn't want anything to hold up construction of the section that runs from Katella Avenue to Miraloma Avenue, he added.

Ameron Makes Pipes

Fifty-two thousand lin. ft. of 3/8-in.-thick steel pipes, coated with cement mortar both inside and out, were manufactured by Ameron International of Rancho Cucamonga for Ken Thompson.

Because such a configuration is not rigid, in engineering terms, they arrived with wooden bracing inside, Markus said. Once the pipe sections are welded together, hand-patched inside and out with mortar and the trench backfilled, they are stable, he added.

"Such pipes are normal for water systems," Markus said.

Colich Construction started production on the pipeline's middle section in mid-2004 and is aiming for a February completion, said Jeremy Juarez, Colich's project manager. "We still have a lot of tunnels to dig," he added.

In the center section, the water pipeline runs from 17th Street north to Katella Avenue in Anaheim and uses about 17,000 lin. ft. of pipes. "We've got some tight spots to lay pipe," Juarez said. The 66-in.-diameter pipes were manufactured by Northwest Pipe Co. of Adelanto.

In the tunnel under Interstate 5, Colich's construction crews encountered debris, mainly old fence posts and chain-link fencing, about 30-ft. down, Deshmukh said. "They had to change their boring machine from a closed face to one with an excavator," the OCWD engineer added.

Markus said he thought the debris came from a 1938 attempt to restore the river bank after a flood.

Ken Thompson crews began work on the 6-mi. southern pipeline section in September 2004, with a finish date set for August 2006, Markus said.

"If it goes as planned, we'll complete this a year early, too," Deming said.

As with the finished section, Ameron International manufactured the pipes, whose diameters range from 78 in. to 66 in. for this southern section. It originates at the new water purification plant, then runs from Ellis Avenue in Fountain Valley to 17th Street in Santa Ana.

Along the entire pipeline, six 5-in., empty PCV conduits were installed, Markus said. "They can be rented for fiber optics in the future," he added.

Three butterfly valves that cover the pipe's diameter were inserted at spots along the 13-mi. length so maintenance workers can isolate portions for future repairs, Deshmukh said. The valves also prevent backflow once the water is pumped from the treatment plant, he added.