Deeper wells may not be contaminated by perchlorate
Seventeen months after South Valley residents discovered that perchlorate was contaminating their drinking water supply, a picture of the situation underground and possible cleanup methods have been announced.
And, in another move forward in the perchlorate fight, Sylvia Hamilton, Perchlorate Community Advisory Group chairwoman, said she has been asked to testify on June 23, before a House committee reviewing a bill introduced by Rep. Richard Pombo, R-Tracy, asking for $25 million to help pay for the effort.
Rick McClure, Olin Corp. project manager for the local cleanup, said Friday at a meeting of the (PCAG) and two-dozen residents that Olin’s consultants from Mactec had mapped the underground aquifer and found perchlorate in mostly shallow areas, about 100-feet deep, leaving open the possibility of drilling for clean water in deeper wells.
The Central Coast Regional Water Quality Control Board, the lead agency in the South Valley cleanup effort, required Olin to produce the map and a plan for water replacement.
Michael Burns, a geologist for Mactec, told PCAG the affected water does not appear to be moving down – in a vertical direction – largely because of deposits of clay, material that does not easily allow filtering through, acting instead as a protective barrier.
“I feel we’ve got a pretty good picture of the aquifer,” Burns said.
WHERE AND HOW
Mactec’s Don Smallbeck made recommendations for removing the chemical from residential water supplies, a move that well owners, public and private, have been waiting for since January 2003.
The most likely methods involve installing treatment systems at either the point of entry (POE) – at the well head, not unlike a water softener in the garage – or point of use (POU) where the system is installed near the taps, similar to under-sink reverse osmosis systems. Each comes with some difficulties.
Smallbeck said POE units are flexible – important because they must deal with different sized wells – are small enough and more easily allow access for maintenance since the unit could be at the wellhead or in a garage.
“This method gives us lots of options,” Smallbeck said.
Both Greg Van Wassenhove, Santa Clara County Agricultural Commissioner and PCAG member Evelyn Heinrichs questioned whether the proposed treatments would include agricultural and irrigation wells.
“That is beyond the substance of this report,” Smallbeck said.
Whole basin remediation was also not included, though McClure said Olin will address that in the future.
Mactec studied the 10 to 18 wells with higher concentrations of perchlorate – 40, 18 and 10 parts per billion – and had come up with individual evaluations for each but not for the dozens of wells closer to 6 ppb or lower.
McClure was careful to point out that individual well owners would be consulted on – and would have to agree with – whichever treatment was suggested for their wells.
Smallbeck also discussed the kind of treatment system that might be used for POE or POU sites.
“The DHS (California Department of Health Services) has approved some scalable (applicable to various sized wells) ion exchange systems that would apply to POU and POE systems,” Smallbeck said. “California is very interested in getting technical certification for these.”
Certification by the federal National Science Foundation is pending on several systems and will take at least six months or more, said Tracy Hemmeter of the Santa Clara Valley Water District, largely because the NSF is also finding nitrates in the water to be a hurdle to certification.
Both San Martin municipal well companies and the City of Morgan Hill use ion exchange systems to clean their water of perchlorate.
A second type, reverse osmosis, he said, is not as scalable or as efficient but has DHS approval for point of use.
Other treatment systems include biological, electro oxidation, electro chemical reduction, electrolysis separation, granular activated carbon and hollow stem filaments – none of which has yet been certified.
Potential impediments to installing treatment systems on private wells, Smallbeck said, include getting property owners to agree to the recommended method, formalizing the agreement – deed restrictions, testing and maintenance access agreements, easements and rights of way and city or county permitting.
Heinrich’s asked who would do the testing and maintenance.
“I don’t think Olin is averse to maintaining and operating these systems,” Smallbeck said, ”because we would want it to be consistent.”
“That’s right,” McClure said. “Olin will monitor and, more than likely maintain, the systems.”
The question of who would pay for the systems was not discussed.
The chemical ended up in the groundwater after 40 years of being dumped in a holding pond at an Olin Corp./Standard Fusee safety flare manufacturing plant at Tennant and Railroad avenues in Morgan Hill. T perchlorate leached down through the soil into the aquifer and has flowed in a southeasterly direction through south Morgan Hill, most of San Martin west of Monterey and, in a lesser concentration, to north Gilroy.
Several hundred private and several municipal wells were contaminated, though most in low concentrations close to levels detectable by tests – 4 parts per billion. A Public Health Goal (PHG) was set this March by the California Department of Health Services at 6 ppb, the point at which water consumers must be notified of the chemical’s presence.
FINANCIAL HELP
Hamilton, a retired teacher, has paid many costs surrounding the perchlorate fight by herself and will not receive any financial help from Pombo’s office or the federal government to cover travel costs.
Gary Shallcross, a member of the Regional Board and an aide to Assemblyman John Laird, D-Santa Cruz (whose district includes Morgan Hill and San Martin) suggested after the meeting that the Regional Board or the water district might find money in their budgets to help Hamilton out.
“But they probably don’t have any extra money,” Shallcross said. “We may have to take up a collection.” More details will be available later.
PCAG was established to keep tabs on studies and work surrounding the local perchlorate issue and to keep the public informed. Besides Hamilton, van Wassenhove and Shallcross, PCAG includes representatives the water district, Mayor Dennis Kennedy and others from the San Martin community,
Carol Holzgrafe covers City Hall for The Times. She can be reached by e-mail at ch********@*************es.com or phoning (408) 779-4106 Ext. 201.
