Megan Stone
Special to Mustang Daily
In Nov. 2012, Pacific Gas and Electric (PG&E) submitted a request for a permit to perform seismic testing in the ocean surrounding the plant that was denied by the California Coastal Commission. In spite of the denial, PG&E is still looking into the possibilities.
Faculty and students at Cal Poly are hoping PG&E does not have to perform more seismic testing in the waters surrounding the Diablo Canyon Power Plant. Seismic testing poses a risk to sea life in the area, they say, but PG&E says it may need to conduct further tests to fully understand the seismic hazard the plant could face.
Seismic testing uses loud sounds to see how faults that lie beneath the surface are structured and if they may pose a threat if an earthquake were to occur, interim dean of research Dean Wendt said. However, the testing poses a threat to a variety of marine life such as endangered blue and gray whales, sea otters and white sharks.
“Basically they’re like explosions,” Wendt said. “So if there was someone who was near those guns when it was set off, they could die.”
The California Coastal Commission did not grant a permit for PG&E to conduct a high-energy offshore test. The test would impact local Marine Protected Areas, which also affects feeding pools for marine mammals and other endangered species, Wendt said.
Since water is a lot more dense than air, the sounds are more intense. Imagine those blow horns people have at sporting events, Wendt said — the equipment that is used for seismic testing is essentially a modified version of that.
But there are other areas in the world that conduct high-energy seismic tests without any long-term harm to marine mammals, PG&E spokesperson Blair Jones said.
“To mitigate any potential harm to marine mammals, we put forth a plan to take protective measures to prevent any harm to marine mammals,” Jones said.
Cal Poly’s Biological Sciences Department has a marine research pier in Avila Beach where many classes and students do various projects and studies. Biological sciences alumna Jessica Williams is concerned about the potential risks of conducting the high-energy test, she said.
“It can be hard to predict the effects the disturbance will have on marine life until it’s too late,” Williams said.
It’s not clear how it will affect fish populations that serve as a food source for larger marine life, Williams said. If fish leave the region, many of the larger marine life that feed off these local fish pools could leave the region and may not return.
Many studies have been ongoing for years, and the risk of skewing the data the pier has helped collect during recent years is a major concern for Tom Moylan, the marine operations manager at the pier.
“We have one of the most biologically rich areas as far as biomass and even species diversity because of the nature of our coastline,” Moylan said. “Based on the sound levels and intensity that they are proposing to use, I would be very concerned about what that would do to our environment.”
The testing could ruin some of these ongoing research projects such as studying the movement of fish populations, Moylan explained. If the sound waves impact the number of the local fish populations, all of that research would be affected.
“Sound travels through water and you can get a concussion effect from the sound and it can physically damage your ear drums and other body parts even if it’s intense enough,” Moylan said.
Just like dolphins use sound waves to stun their prey, the blasts from the seismic testing would have the same or a greater effect on the marine life in the area. In PG&E’s proposal, there are cautions that will be put into effect to keep boaters, divers and others out of the water.
“Those kind of cautions worry me,” Moylan says.
The seismic study consists of four parts, two onshore tests and two offshore tests. PG&E has already performed the 2-D and 3-D onshore tests and the 3-D low energy offshore tests last year. The California Coastal Commission denied approval for the 3-D high energy offshore testing, Jones said.
“The big concern was, and this was why the CCM didn’t approve it, is that they didn’t believe the results that could be gained through the study outweighed the potential impacts of the study,” Jones said. “We appreciate the effort that their staff did in looking at the proposal.”
PG&E’s priority is to avoid any long-term impact to large marine mammals and other marine life in the area while safely conducting the proposed tests, Jones said.
“Before the research begins, they would slowly start up with lower level sounds,” Jones said. “These will serve as a warning to marine mammals to leave the general area.”
There is a safety zone that would be established around the testing site, Jones said. A 3.8-mile radius around the vessel will be established, in which the sounds are expected to be around 160 decibels. There will be spotters on the testing vessel and surrounding vessels to help spot marine mammals, if they begin to come too close to the testing site, Jones said.
The sound generated directly at the source is around 250 decibels, Jones said. Some survey models have shown that levels of 160 decibels could reach some shoreline areas such as parts of Montaña de Oro State Park, Morro Bay Sandspit and an area northwest of Cayucos.
“A human would have to be exposed to 150 decibels for 15 minutes or longer to receive any harmful effects,” Jones said. “Anything greater than 154 decibels can cause hearing loss.”
PG&E is now in the process of analyzing the data it has collected from the three recent studies and comparing it to past data that has been collected regarding the seismic hazard of the region. The next step is to look at what information it has obtained from these results and move from there.
When assembly bill 1632 passed in California in 2006 it called on the California Energy Commission to evaluate the impacts earthquakes might have on California’s largest nuclear plants, Jones said. In 2008, the California Energy Commission’s assessment of Diablo Canyon requested further research into mapping the fault zones surrounding the area. The test called for the use of 3-D high energy tests.
The recent 2-D and 3-D onshore and the 3-D low energy offshore tests found that one of the faults appears more vertical than initially thought, Jones said. It could potentially reduce the seismic hazard of that fault.
If the three tests that have already been conducted reveal that PG&E may need to do some further research into the seismic hazard of the area, then it may it need to move forward with more testing, Wendt said.
However, if the recent tests show that there is a larger seismic hazard than previous studies have shown, then they either need to reevaluate the seismic safety of their current structure or shut the plant down, Wendt said.
“They have two basic options; PG&E can either retrofit the plant, or they can shut it down,” Wendt said. “That means having to go in and make it more seismically safe, which is hugely expensive.”
PG&E’s next step is to continue with analysis of the recently collected data and compare this data with what they already know about the area, Jones said. PG&E’s long-term seismic program, which has been in place for decades, consists of geologists, scientists and other field specialists that assist in evaluating the data that it receives from the tests.
“The bottom line right now is that we are currently assessing all the data we previously had and all the data we have just received from the newer seismic studies to see if we need to further study the seismicity of the area and look at how to proceed,” Jones said.
Megan Stone contributed to this article.