Perchlorate cleanup order revised

A revised draft of the cleanup and abatement order for the
10-mile groundwater perchlorate plume running below the Llagas
Creek subbasin now includes a specific cleanup schedule and
details.
MORGAN HILL

A revised draft of the cleanup and abatement order for the 10-mile groundwater perchlorate plume running below the Llagas Creek subbasin now includes a specific cleanup schedule and details.

Simultaneously to a requirement that it finish the plan for “deep aquifer characterization work” by April 15, 2008, the order also requires the polluter, Tennessee-based Olin Corp., to implement the intermediate aquifer system in less-polluted areas as previously scheduled. The staff of the Regional Water Quality Control Board, Central Coast Region, is also preparing a detailed response to Olin’s Cleanup Work Plan, including “details concerning the proposed remedial contingency plan and performance monitoring program.”

On Dec. 7, the board is slated to review the report, prepared with input – manifested in the dozens of pages of comments – from stakeholders including the cities of Gilroy, Morgan Hill, the Santa Clara Valley Water District, which comprise the Perchlorate Working Group. 

According to the report, the staff recommends that the board approve the order as revised. The recommendation comes on the heels of a number of public hearings held during the Perchlorate Community Advisory Group meetings. 

Board staff made changes “as deemed appropriate,” it states in the report. 

Staff “revised the proposed cleanup order to require Olin to implement aggressive and prompt groundwater cleanup … not only within Priority Zone A, but also within Priority Zone B in the intermediate aquifer,” the 9-page report says. Tests have shown that Zone A of the plume contains the highest concentration of perchlorate, in excess of 24.5 parts per billion, while Zone B has less. The report also states the board has not accepted Olin’s alternative cleanup goal of 6 ppb and requires a cleanup to “background,” or nondetectable levels but also states “It is not prudent at this time to establish a cleanup level.”

Board staff weren’t available by press time for further comment.

“By targeting Priority Zone B … cleanup time-frames will be accelerated and will result in the effective cleanup of the affected domestic supply wells much sooner than with the present approach,” the report continues. 

In response to the Perchlorate Working Group’s comments that no active groundwater cleanup has occurred at the site, the board staff disagrees: 

“… Staff would like to point out that cleanup of perchlorate has occurred at 15 wells that are currently fitted with ion exchange systems. For example, the West San Martin Water Works and San Martin County Water District community supply wells that serve water to numerous west San Martin households have been fitted with ion exchanges systems since April 2004.”  

Although “Olin’s progress with respect to required investigation and cleanup activities is excellent,” the report concludes that Olin “has not demonstrated … that there are other sources of the long-term perchlorate concentrations for the majority of the Llagas Subbasin including the area north and northeast of the facility or other discrete areas within” the basin.  

Susan Siravo, a spokesperson for the Santa Clara Valley Water District, said “it’s too early to make any comments on the report.

“Our expert staff will be going through it thoroughly in the coming days. We are sensitive to the needs of people who have been affected and we look forward to a resolution for them.” 

Other stakeholders weren’t reachable by press time.

REVISED CLEANUP ORDER

To view the staff report and the revised cleanup and abatement order, go to:

http://www.waterboards.ca.gov/centralcoast/Board/Agendas/2007/120707/Item15/Index.htm.

The Perchlorate Community Advisory Group will meet at 2 p.m. Friday at the Lions Club in San Martin.