Olin Corp. has presented its plan for cleaning up soil and
groundwater polluted by perchlorate from its Tennant Avenue plant
and says one-to-two years may do the trick.
Olin Corp. has presented its plan for cleaning up soil and groundwater polluted by perchlorate from its Tennant Avenue plant and says one-to-two years may do the trick.
Under fire for polluting the South Valley underground aquifer – and hundreds of wells from Morgan Hill to Gilroy – the company was ordered by the state Regional Water Quality Control Board, Central Coast Region, to propose such a plan and to follow through to fix the problem that has caused health worries and economic fears for the entire region.
On Aug. 12, the company complied.
Olin had hoped the regional board staff would accept the plan Tuesday but will have to wait until next week for a final determination
John Mijares, water resource control engineer for the regional board, said his agency had discussed the report and found that, in concept, it can work.
“It is acceptable,” he said. “However, we reserve our right to comment on it; we still have a technical meeting with all other interested parties, except Olin, on Tuesday (Sept. 2). We told them to proceed with installation.”
Mijares said the RWQCB will provide its written comments by Friday, Sept. 5, possibly even earlier, on Tuesday.
The plan for a combined full-scale remediation of perchlorate-affected soil and on-site (in-situ) groundwater at the former Olin/Standard Fusee plant on Tennant Avenue was prepared for Olin by GeoSyntec Consultants of Atlanta.
The report’s intent was to treat both soil and on-site groundwater by removing the water through a well in the shallow aquifer at 30 to 65 feet below the surface and one well in the intermediate aquifer at 90 to 110 feet.
The extracted water would be treated with an ion-exchange treatment plant similar to that currently used to treat water successfully for perchlorate at the city’s Nordstrom well. The method uses disposable resins that collect the perchlorate ions from water molecules, leaving the water clean; the perchlorate-laden resin is then trucked off to be burned, dumped or otherwise disposed of.
Part of the treated water will be recharged through the polluted soil that, the report said, will “accelerate leaching of perchlorate from the soils to groundwater, where it can be effectively extracted and treated via ion exchange.”
The goal of this on-site leaching method is to flush perchlorate from the soils in as short a time as possible, possibly one year, the report said.
Rick McClure, spokesman for Olin, said it was important to realize that information is still being collected on infiltration rates (for fresh water to clean the soil).
“These factors will control the cleanup rate, the number of flushings and timeline in which a cleanup would occur,” he said. “It may take four or five flushings or more. Regardless of how long it takes,” he said, “two weeks to two years, the process will be monitored by the regional board and when it is cleaned up it will be shut off.”
Two main challenges occur with on-site leaching. One is the potential of perchlorate spreading laterally when surface water “infiltrates” the soil down into the groundwater. The second involves the different rate of perchlorate leaching with low-permeability clay and silty clay layers. These soils, being less porous, may slow the cleansing rate.
The report said that the RWQCB, Central Valley Region, has already approved a field demonstration of a similar process to treat a superfund site at an Aerojet plant in Rancho Cordova near Sacramento. The Rancho Cordova perchlorate situation was discovered in 1996 and has been the subject of lawsuits and major community action.
One such lawsuit was settled this week with an agreement between Aerojet, Boeing and the County of Sacramento – described as “win-win” – to remediate the affected soil and groundwater. The two companies will contribute $25 million to support the county’s water solution.
A “90 percent Design Report” on soil and groundwater remediation for the Olin site is scheduled to be ready on Nov. 21, 2003, the Olin report said.
The RWQCB will discuss the Olin remediation plan at a meeting in Salinas on Friday, Sept. 12, City Council Chambers Rotunda, 200 Lincoln Ave., Salinas. The meeting begins at 8:30 a.m.; the Olin issue is number nine on the agenda. Details: www.scrcb.ca.gov
