LOS ANGELES (AP) — Citing harm to marine life, California coastal regulators on Wednesday soundly rejected a utility's plan to map offshore earthquake faults near a nuclear power plant by blasting loud air cannons.
The unanimous vote by the California Coastal Commission came after an hours-long public hearing attended by environmentalists, fishermen and residents who were overwhelmingly opposed to the seismic testing.
The proposed survey by Pacific Gas & Electric Co. involves firing sonic pulses into the ocean. Sensors on the seafloor would pick up the echoes to create 3-D maps of geologic faults that the utility said are needed to understand the seismic hazards around the Diablo Canyon facility.
"If you live near a nuclear plant, wouldn't you want more certainty in the assumptions that are being made?" asked Mark Krausse, a PG&E director.
But commissioners said the impact to sensitive marine mammals along the Central Coast would be too great, and they felt PG&E did not make the case that such testing was necessary.
In a statement, PG&E said it was disappointed with the decision and will evaluate its next move. It could reapply for a permit, but several commissioners indicated they would be hard-pressed to change their minds if the issue came up again.
The commission's staff had urged the panel to reject the plan. In a report this month, the staff said sonic blasts would cause "significant and unavoidable impacts to marine resources." More than 7,000 sea mammals would be disturbed by the ear-piercing noise, including fin whales, blue whales, humpback whales, and harbor porpoises.
PG&E acknowledged that the noise could cause short-term disruption to animals, but said similar research has been done around the world without long-term harm.
The damage that strong shaking can cause to nuclear reactors came under scrutiny after the 9.0-magnitude earthquake off Japan's coast triggered tsunami waves, which swamped the Fukushima Dai-ichi plant last year.
Even before the Fukushima disaster, state law mandated that utilities conduct extensive seismic studies of nuclear facilities, but did not specify the type of research.
Perched on an 85-foot bluff above the Pacific, Diablo Canyon sits within three miles of two underwater earthquake faults, including one that was discovered in 2008.
PG&E came up with a four-pronged approach that includes the use of high-energy seismic imaging technology. Under the ratepayer-funded study, a research boat would tow 18 air guns that would emit sonic blasts into the ocean every 10 to 20 seconds for several days. The utility had hoped to conduct the study between November and December to avoid peak breeding and migration seasons.
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