SAN MARTIN
– One year and one day after 2,000 or more angry South County
residents nearly rioted over perchlorate contaminated wells, a
calmer group met Friday with the company that poisoned their water
supply.
SAN MARTIN – One year and one day after 2,000 or more angry South County residents nearly rioted over perchlorate contaminated wells, a calmer group met Friday with the company that poisoned their water supply.
Under the watchful eye of Sheriff’s deputies, Olin Corp. representatives announced a more than half-million-dollar cleanup plan for 6,500 square feet of soil at the company’s now-defunct factory site on Tennant Avenue in Morgan Hill. The company will compound its existing treatment of the groundwater at the site with the state’s mandated course of action for cleaning the soil.
Olin representatives told the area’s leading perchlorate watchdog group Friday the most contaminated portion of the site would be perchlorate-free by late 2004. However, it will be at least a few years before the remainder of the site will be void of the rocket fuel ingredient.
It was the company’s first public meeting since it was announced that perchlorate leaked into the groundwater supply of South County. To date, nearly 500 private wells from Morgan Hill to north Gilroy have been tainted with unsafe levels of perchlorate.
“I’m impressed with what they’re doing now. This is the best compromise,” San Martin resident Bob Cerruti said after the session with Olin’s project manager and lead consultant for the cleanup effort. “We’ve been fighting for a year and haven’t gotten anything for it so far.”
Olin wanted to do a cheaper version of soil cleanup but was forced by the state earlier this month to do a more involved treatment process. Now, it will begin applying for permits and designing a plan that will use microorganisms to degrade perchlorate into harmless chloride molecules.
Olin’s consultant, Evan Cox of Geosyntec, spent more than an hour explaining the science of the cleanup process to the perchlorate advisory group.
Essentially, Olin will inject nutrients into the soil which existing bacteria will use as food to help digest the perchlorate. No foreign bacteria will need to be used.
Cox said two types of treatment will take place. One will excavate soil contaminated at the level of 7,800 parts per billion and treat it. Once it’s cleaned, the soil will be returned to where it was dug up.
Soils in the 6,500-square-foot area contaminated at the level of 50 ppb will be treated without excavation. This process will take at least a few years to clean out all the perchlorate.
By April, the plan should be ready for approval by the state’s Regional Water Quality Control Board. Then, a four-to five-month testing period will occur to verify the treatment is working. Full-scale operation should begin by fall.
With ion-exchange filters already installed on site to clean up the groundwater, any soil contributing to water contamination over the next few years will be insignificant, Cox said.
“The ion-exchange system will be acting like a catcher’s mitt to make sure no contaminated water gets off site,” Cox said.
Olin escaped the most expensive soil cleanup plan, which would have called for excavation and disposal of the most contaminated dirt and treatment of the remaining soils with microorganisms.
“That would have cost about $5.4 million to perform,” Cox said.
The bulk of the cost would have come from the excessive amount of hauling the excavated dirt. Roughly 1,000 cubic yards of soil would have been hauled.
About 30 residents attended the nearly 20-member perchlorate advisory group session Friday as a Sheriff’s deputy looked on to keep the peace. As the meeting let out, a second deputy was present as well.
“It was scary last year. As far as I know there were no physical altercations, but people’s cars got damaged,” said Sylvia Hamilton, chairman of the perchlorate advisory group. “It was a case of people wanting information and quickly realizing that all the officials on the panel didn’t really know much about the issue yet. And the audience was filled with lawyers, which got people even more revved up.”
Olin did not send representatives to that session, which was held at Gwinn Elementary School in San Martin.
Hamilton said she had a good working relationship with the company at the time, but soon representatives cut off communication due to lawsuits that were filed.
At Friday’s meeting, Olin’s project manager Richard McClure said he and Cox would focus only on the soil cleanup plan. However, McClure did spend several minutes explaining a five-page document outlining everything Olin has done over the year to clean up its mess and bring clean water to people’s homes.
“I’ve never seen, known of, or worked on a project that has accomplished so much in so little time,” McClure said.
Olin’s five cleanup options
Expensive
• “Excavation and off-site disposal”: Dig up the contaminated soils, clean them using microorganisms and move them elsewhere.
• “Excavation and ex situ bioremediation”: Dig up the contaminated soils, clean them using microorganisms and put them back where they came from.*
Moderate
• “In situ bioremediation”: Leave the soil where it is and clean it using microorganisms.**
• “In situ soil washing”: Leave the soil where it is and clean it using water.
Cheap
• “Monitored natural attenuation”: Do nothing, let the microorganisms filter out the perchlorare.
* The state will make Olin use this alternative for the contaminated Morgan Hill site.
** Olin wanted to use this alternative for the contaminated Morgan Hill site.
