The perchlorate plume swishing through South County’s water
table has already taken years to locate and characterize, but
there’s still more work to be done to uncover all of its obscure
movements at various depths and latitudes, according to state water
officials and Olin Corporation engineers.
Morgan Hill – The perchlorate plume swishing through South County’s water table has already taken years to locate and characterize, but there’s still more work to be done to uncover all of its obscure movements at various depths and latitudes, according to state water officials and Olin Corporation engineers.
In a June 29 letter of response to Olin Corp.’s March 2006 so-called “characterization report,” the California Regional Water Quality Control Board agreed with Olin’s engineering firm, Mactec, that more data are needed to trace the lateral extent of perchlorate in the intermediate and deep aquifers to the south, and to the west, of the Tennant Avenue road flare factory that is believed to be the source of the contamination.
Nevertheless, the water quality control board is not requiring Olin Corp. to further update its recent perchlorate report though water officials say several statements in the report concerning the possibility of other sources of perchlorate are made by Mactec without any analytical data.
Those possible sources alleged by Olin include bleach used by food processing facilities, bleach used to disinfect wells, highway safety flares, fertilizers and a nearby rocket motor manufacturer.
In its response, the water board remains firm that Olin is the responsible source of the perchlorate detections in ground water impacted by the Olin site.
Hector Hernandez, the regional water board engineer overseeing the cleanup effort, said those concerns will be addressed in future reports by Mactec, which will also present results of future characterization actives to the board.
He added that state water officials are mostly pleased with the “tremendous effort” put forth by Olin Corp. and Mactec, which have drilled numerous wells and have monitored hundreds more to track the plume’s concentration and physical movements.
“There’s always been technical disagreements on issues, but things are moving forward at reasonable pace,” Hernandez said.
Perchlorate is a type of sodium that affects healthy thyroid activity if ingested at high enough levels. California’s public health goal for drinking water is 6 parts per billion (ppb) or less perchlorate. According to data collected by Mactec, many of the drinking wells – from San Martin to Gilroy – affected by the defunct factory’s discharge of perchlorate are now testing below that level.
As a result, Olin has canceled shipments of free bottled water to hundreds of households over the last four weeks, riling many local residents who attended a June 29 community meeting in San Martin to confront Olin Corp. Vice President Curt Richards.
A top concern raised by residents at the meeting was that Olin could be mishandling its records of contaminated wells it has monitored, leading to errors in canceling bottled water accounts.
Hernandez said there were several calls to his office last week from residents on this issue.
“We alerted Olin there were one or two mistakes with people who were going to be cut off,” he said.
Citing Olin’s corporate policy, Mactec Principal Hydrogeologist Mike Taraszki would not comment Thursday.
As planned, the latest report preceded Olin’s recent cleanup feasibility study,” which was submitted by Mactec on June 30. The document is more than 100 pages long, and defers until August any cleanup solution for the area directly surrounding the Tennant Avenue factory.
The study addresses options for cleaning the areas further south of the site, suggesting more of the same: a passive monitoring program of the alleged water contamination that would be carried out over 20 years to the tune of $5.6 million.
Hernandez said the water board is currently reviewing the proposal, and would have feedback for Olin and Mactec by September. The water board may make revisions to the document.
