Olin Submits Work Plan

Company focuses on highest concentrations of perchlorate
Morgan Hill – Olin Corporation’s recent cleanup proposal could take almost two years to complete, focussing on the most polluted areas of the South County water table.

The roughly 550 acres directly southeast of the company’s now-closed road-flare plant on Tennant Avenue have seen perchlorate readings of 24.5 parts per billion or higher since 2001. The state’s public health goal is 6 parts per billion.

The work plan, a.k.a. the Area I Plume Migration Control Work Plan, was submitted Dec. 6 to the Central Coast Regional Water Quality Control Board. The plan calls for extracting groundwater, removing pollutants and then either injecting it back into the soil or sharing it with nearby water municipalities, such as the city of Morgan Hill, where customers would drink the water Olin has cleaned. 

The cleanup proposal would take more than 20 months to implement and is being reviewed by the Central Coast Regional Water Quality Control Board until the end of January. 

Olin may need to clean other parts of South County’s water table and will submit another work plan in 2007 for those areas.

Olin is responsible for an underground plume of perchlorate stretching southeast from the company’s old road-flare plant on Tennant Avenue, next to the Union Pacific Railroad, in Morgan Hill. Perchlorate contamination was first reported by the company in February 2001 when it was trying to sell the factory. 

From 1956 to 1995 Olin and Standard Fuse operated the factory where perchlorate leaked into the ground, possibly from an evaporation pond for factory water, on-site incineration of flares and accidental spills. The evaporation pond was used as an alternative to disposing polluted water into storm drains.

Perchlorate is a chemical used in rocket fuel, explosives and road flares. It is known to disrupt thyroid function and prenatal growth and development. Scientists are debating on how much perchlorate it takes to cause health problems.

Last Spring, Olin submitted a plume report that identified four geographic areas southeast of the factory. Area I is roughly bordered by U.S. 101, Middle Avenue, the Union Pacific Railroad and the northern boundary of the Tennant Avenue factory. The plume report addressed groundwater flow, current and historical perchlorate concentrations and the number of detections above the California Office of Environmental Health Hazard Assessment’s public health goal of 6 parts per billion.

Along with the plan, Olin submitted its Area I Plume Migration Control Feasibility Study, which developed four ways of removing groundwater and treating it. While the feasibility of plume migration control is still being evaluated for the entire plume, the water board requested the Area I Work Plan to be finished this month so remediation within the highest concentration zones could begin more quickly.

Area I contains concentrations of perchlorate as high as 24.4 parts per billion and above – which are the highest levels detected by Olin in the South County watershed. According to Olin, all readings of 24.5 parts per billion or higher are located in area I.

The company would spend eight months exploring how to treat water so it could go directly into drinking water systems, according to the proposed schedule.

OLIN’S CLEANUP PLAN

-Groundwater extraction system

-Untreated water conveyance system

-Perchlorate treatment system

-Treated water conveyance and

disposition system

-Performance monitoring network

Tony Burchyns covers Morgan Hill for The Times. Reach him at (408) 779-4106 ext. 201 or

tb*******@mo*************.com











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