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California | Environment & Forest Defense

PGE to conduct seismic tests which could harm marine mammals
by sfgate
Wednesday Nov 14th, 2012 7:32 AM
Earthquake fault lines, one of them little understood, snake beneath the seabed near the Diablo Canyon nuclear power plant on California's central coast.

Now Diablo's owner, Pacific Gas and Electric Co., wants to map those faults in 3-D detail, assessing the threat they pose to the plant. But the company's proposed testing method - blasting the sea floor with air guns that generate intense sound waves - could kill millions of young fish.

The California Coastal Commission will vote Wednesday on whether to let PG&E conduct the tests. At 250 decibels, the sound waves can penetrate silt and rock, revealing geologic structures four miles deep. They can also disorient, deafen or kill wildlife that strays too near. The commission's staff has recommended rejecting PG&E's proposal.

The seismic testing plan has angered environmentalists and alarmed fishermen who make their living near the plant, which occupies a rocky cove near San Luis Obispo.

"It's dumb, it's unnecessary, and the fact is it's going to do a lot of damage," said Zeke Grader, executive director of the Pacific Coast Federation of Fishermen's Associations.

And yet, many of the plan's opponents feel torn. They very much want more study of the faults near Diablo. Last year's meltdown at the Fukushima Dai-ichi nuclear plant in Japan, an accident triggered by an earthquake and tsunami, stoked old fears about the safety of reactors on the quake-prone California coast.

"We want to get that information, but we don't want to hurt marine life in the process," said Amanda Wallner, an organizer for the Sierra Club environmental group.
Monitoring the area

PG&E acknowledges that the tests will disturb the local marine habitat but insists that the disruption will be minor and temporary.

The utility, based in San Francisco, will monitor the testing area for whales, porpoises and other marine mammals. If any wander too far into the testing zone, researchers will stop firing the air guns, said spokesman Blair Jones.

"We have rigorous plans in place to protect marine mammals and marine life," he said. "PG&E's committed to doing this work safely and in a manner that respects environmental values."

PG&E plans to use a specially outfitted ship from the National Science Foundation to conduct its tests. Air guns towed by the ship at a depth of 30 feet would blast sound waves at the ocean floor. Underwater microphones, towed in long strings behind the ship, would listen as the sound waves bounced off rock formations below the seabed.

The air guns would fire every 11 to 20 seconds. Testing would last nine days. Should the coastal commission and several federal agencies approve the project, the tests could happen by year's end.

Seismic issues have dogged Diablo Canyon since PG&E first proposed building the plant, which opened in 1985. But they've taken on new urgency in recent years.
Disaster's impact

In 2008, the U.S. Geological Survey found a fault just offshore from the plant, naming it the Shoreline Fault. It lies closer to shore than the larger Hosgri Fault, whose discovery in 1971 forced PG&E to revise the plant's design.

Even before scientists identified Shoreline, state officials were pressing PG&E to do more seismic testing around the plant. Shoreline's discovery added to that push. Then the Fukushima meltdown focused worldwide attention on seismic safety at nuclear facilities.

At the time of the disaster, PG&E had been in the process of trying to renew Diablo Canyon's operating licenses with the federal government, potentially extending the plant's life through 2045. But in the wake of Fukushima, PG&E asked the U.S. Nuclear Regulatory Commission to delay making a final decision on renewing the licenses until the company could finish its seismic studies.

Continued: http://www.sfgate.com/science/article/Diablo-Canyon-seismic-safety-vs-sea-life-4035463.php#ixzz2CDA0WY7O