Even If An Earthquake Strikes

Spring enters slowly at Silverwood Lake. The sun is out, but there's a definite chill in the air, especially as the wind breezes through the sycamores and oaks. A few hardy anglers are trying their luck near the shoreline, but the campgrounds are deserted, the marina quiet, and only the ground squirrels scamper along the trails.

Just a few months ago, Silverwood Lake was less than half-full, drained of much of its water so construction could be completed on a structure that would help earthquake-proof the drinking water of more than 12 million Southern Californians. With the project nearly done and the lake refilling, things are trying to return to normal.

But the placid scene belies the hurried schedule and flurry of activities that marked this project as a bit out-of-the-ordinary.

The Problem and the Fix

Located about 30 minutes north of the city of San Bernardino, Silverwood Lake was built by DWR in the early 1970s as a State Water Project reservoir to store water destined for homes, farms, and businesses in the Southland, as well as for recreation and wildlife enhancement. In 1988 DWR engineers began studies of the San Bernardino Tunnel to optimize power production. The 3.8-mile-long tunnel conveys water leaving the lake through an intake tower to Devil Canyon Powerplant, capable of generating enough electricity to serve about 88,0000 households a year.

As part of the studies, the engineers looked at the intake tower. They determined that the tower, designed in 1967, did not meet current acceptable seismic design standards. In fact, they surmised that the tower could be damaged if a magnitude 5.5 earthquake occurred along the San Andreas Fault. Such a failure would interrupt Southern California water deliveries with dire economic and public health consequences for those living in San Bernardino, Riverside, Orange, Los Angeles, and San Diego counties.

Recognizing this serious public safety threat, the Federal Energy Regulatory Commission—which issues a license for DWR to operate Devil Canyon Powerplant, the lake, the tunnel, and intake tower—ordered the Department to strengthen or replace the intake tower. So DWR design engineers went to work.

Al Rock lead the engineers who decided that building a new tower was the best response to the earthquake challenge. "It had several advantages," he says. "We would be able to incorporate the latest seismic design criteria into the project design. It would substantially reduce the time needed for us to draw down the lake to its lowest level and minimize any interruption in water deliveries to users downstream. Additionally, it would reduce the degree of drawdown needed to complete the project and in turn minimize any potential impacts to recreation and wildlife."

In designing a more seismically stable tower, DWR engineers studies other similar structures, borrowing features from different designs and merging them into their own concept. the new "Y" or funnel-shaped intake tower would be 125 feet (compared to the 191-foot height of the existing one) and would draw water from one or a combination of four tiers. Besides the unique design, the tower's construction would take advantage of today's strong grade steel and concrete.

After the Design

Designing the tower, however, was only part of the story. Constructing it was quite another.

Construction of the new tower meant different things to different people. For the California Parks and Recreation staff, who operate the state park at Silverwood Lake, it meant a lower lake surface, fewer visitors, and reduced revenues. For environmentalists, construction activities required unwanted and potentially harmful disruptions to the lake's wildlife and habitat. And for the Department, building a new tower—and quickly—would help ensure continued water deliveries, even in the event of an earthquake, to its contracting agencies who depend on the lake.

To clear the way for the tower's construction, DWR staff decided to prepare a mitigated Negative Declaration in lieu of an environmental impact report because they were confident that all potential impacts from the construction could be mitigated.

"We looked at the lake's entire aquatic and terrestrial ecosystem and determined how the project's construction would affect the various environmental resources—namely the fishery, wintering bald eagles, and recreation," says Charles Keene, the project's environmental coordinator. "We concluded that any potential impact could be mitigated to a level considered less than significant according to CEQA (California Environmental Quality Act) and that is what the Negative Declaration basically states."

Working with Departments of Fish and Game and Park and Recreation, DWR staff began planning mitigation strategies for the lake's fishery and eagles as well as for recreation. Fishery mitigation projects included planting of grasses and willows along the lake's shoreline, placing fish shelters and rock reefs, conducting a three-year study to monitor the fish population, and, if necessary, re-stocking the lake with warmwater game fish. To protect the eagles, construction activities would be limited during the winter months, blasting for excavation restricted, and experts hired to study eagle behavior as a result of the project. And for recreational impacts, a public information program would be established to encourage visitors to return to Silverwood Lake after the project's completion.

But DWR's decision sparked its own adverse reaction from the Southern California Bass Council and a few concerned environmental groups. They charged that the mitigated Negative Declaration did not satisfy CEQA , and the mitigation measures proposed were inadequate. Constructing the tower, as they saw it, would irreversibly damage Silverwood Lake's fishery and drive away its bald eagle population, so they hoped to halt the project, perhaps indefinitely through litigation (see sidebar," the Legal Side," below)

Though the lawsuit itself did not cause the desired delay, getting FERC's approval to proceed took longer than anticipated, and time ran out for a 1994 start date. "Because we had to do certain work only during certain times of the year so that it wouldn't affect water deliveries, we had to wait for the next window of opportunity," explains Al Rock.

In September 1995, the first drawdown of the lake, to 43 feet below its normal level, commenced and the contractor, the San Francisco firm of Shank/Balfour Beatty, began work in and around the site. The target completion date was about 21 months away.

Construction Challenge

For Skip Cochran, construction field engineer responsible for the project, the tower's construction was a fairly standard job—except for the extremely tight schedule. Two phases of construction were timed during two drawdowns, with the second one scheduled for October 1996 when the lake would go down another 50 feet. Refilling would begin in the spring so downstream water agencies could gear up for the heavy demands of warmer weather.

Even with the best of intentions, schedules change and delays arise. Throw in the timing of a repair that shuts down the California Aqueduct upstream of the lake and problems in manufacturing the tower's intake and bulkhead gates, and the time crunch becomes even more crucial.

"We did everything we could to stay on schedule," says Cochran, one of eight DWR people on the job, most of them construction inspectors. "Since the beginning, we worked two shifts a day, six days a week."

The plans called for excavating the site and constructing the tower and a 150 foot-deep access tunnel shaft. From the shaft an 18-foot diameter, 500-foot-long tunnel would be excavated simultaneously in two directions—one toward the new tower and the other eventually connecting with existing San Bernardino Tunnel. The new tunnel was excavated through mostly granite walls, in which holes were drilled to place explosives. "We usually cleared about eight feet a day," says Cochran. "If we were lucky, we did 16 feet."

Excavating the site of the new tower was just as demanding. "The type of excavation we did was first for the Department," says Al Rock. "We cut the slope vertically and put in bars to reinforce the earth, a technique that few people have done." This feat was especially notable because of its scale. The depth of the excavation was 120 feet at its deepest point.

Overall, the construction went well. "Better than we thought it would," adds Rock. "The materials we encountered during excavation were better than expected, and the contractors and their crews did a great job."

Environmental Monitoring, Eagles, and Fish

Even before the truck and heavy equipment moved in, work was underway to protect the environment. Photographs were taken of the beaches that would later be exposed during the drawdowns to erosion by winter rains and of roads that would bear heavy construction traffic. "We wanted to monitor these areas so that they can be returned to how they were before the project," says Angela Bonfiglio with DWR's Southern District office.

She, and other environmental specialists, also kept a watchful eye on construction activities, making certain they followed such regulations as preventing runoff from the project site from entering the lake, and properly storing and disposing of hazardous wastes such as fuel, coolant fluids, and hydraulic oils.

At the same time, DWR's plans for mitigating environmental impacts were put into action. The Predator Bird Research Group from the University of California at Santa Cruz initiated a three-year study on how the project would affect the eagles that frequent the lake, as well as on general eagle behavior in the San Bernardino Mountain region. The region , which includes Silverwood Lake, is a wintering ground for the southern bald eagle, listed by the state as endangered and by the federal government as threatened. for several years, eagles have been observed roosting and foraging at the lake. A few years ago, one pair of eagles nested and laid eggs, though they didn't hatch.

Fears that the eagles there would be driven away by the construction proved to be unfounded. During the two winters that the construction spanned, eagles were seen perched in trees overlooking the construction site. Construction crews reported watching one dive into the water near the existing tower to catch fish.

"We didn't feel the lake's drawdown would adversely affect the eagles. They are opportunistic feeders," says Charles Keene. "Because of the drawdown, some fish were caught in small pools, and the eagles will take advantage of an easy meal."

Another major environmental issue centered on Silverwood Lake's renown largemouth and striped bass fishery. Fishing groups believed that the lake drawdowns, especially the second phase, would harm that fishery or permanently change the conditions under which the hatchery was established and flourished.

"We are doing all we can to make good our goal of 100 percent recovery of the largemouth bass within four years of the project's end," says Keene. He cites efforts which include grass and willow plantings along the lake's shoreline to provide shade and cover for fish, plus more habitat in the form of rock reefs and 640 fish spheres, the latest in fish habitat. Each sphere, measuring u p to 6.5 feet in diameter, comes complete with plastic limbs and leaves that promote bio-film , a food source for fish. Besides their snag-free design for fishing tackle, the spheres will not decompose, unlike Christmas trees and hardwood bushes often used as habitat.

"Our strategy is to provide habitat and cover for small fish, which is currently limited. Over time this will increase the fishery population and productivity," explains Keene, "and hopefully accelerate the recovery of the lake's fishery."

The Main Point

After the dust from the construction settles, the eagles return , anglers are catching their prize fish, and recreationists once again flock to the lake to boat and sun, one outcome remains clear: The new intake tower at Silverwood Lake now stands ready to ensure that SWP water deliveries to Southern California will continue to flow with as few interruptions as possible—even if an earthquake strikes.

sidebar
The Legal Side

In late November 1994, the Southern California Bass Council, Sierra Club, Audubon Society, and the Save Our Forest Association filed suit again DWR challenging the sufficiency of the mitigated Negative Declaration . They claimed the environmental documentation did not provide sufficient mitigation for the project's potential adverse effects. The San Bernardino Superior Court judge, who heard the case in April 1995, disagreed. The ruling validated the Department's mitigation plans for fish, wildlife, and recreation.

The petitioners appealed the ruling in June 1995, but did not request a temporary restraining order which could have prevented the work from proceeding. Construction began at Silverwood in September 1995. In October 1996, the state appellate court upheld most of the trial court's decision reaffirming DWR's mitigation measures—except those involving the fishery.

The appellate ruling found that the fishery mitigation measures, as described in the Negative Declaration, were not adequate because performance standards regarding restocking of fish in the lake were not specified. The appellate court remanded (returned) the case to the trial court for resolution of this issue. (Since the completion of the mitigated Negative Declaration, an April 1995 Fishery Mitigation Plan has been approved by Fish and Game and FERC, and is now in effect.)

The critical second phase lake drawdown was set for late October (as scheduled in the mitigated Negative Declaration). However, just before the work began, the petitioners sought to halt the drawdown with a temporary restraining order. This time, the appellate court agreed and issued a temporary stay prohibiting DWR from further drawdown of the lake. (The appellate court ruling did not specifically prohibit DWR from proceeding with the project.)

The Department moved quickly to inform the court that such an order would result in severe and unavoidable water shortages for several hundred thousand persons dependent on Silverwood Lake for their daily water supply. In response, the court lifted the stay and allowed DWR to proceed with the planned drawdown.

Undaunted, the petitioners then filed a Petition for Review in the California Supreme Court in November 1996. The petition sought to overturn the appellate court's rulings as well as reinstatement of the stay order. In February 1997, the court declined to hear the case and returned the matter to the San Bernardino trial court to review DWR's fishery mitigation plan as ordered by the Court of Appeal in October 1996.