[Water_news] 4. DWR'S CALIFORNIA WATER NEWS: WATER QUALITY - 6/25/08

Department of Water Resources

California Water News

A daily compilation of significant news articles and comment

 

June 25, 2008

 

4. Water Quality –

 

 

Lodi drafts plan to clean up toxic chemicals in water

The Stockton Record- 6/25/08

By Keith Reid, Staff Writer

 

LODI - A week after announcing the final settlement in its lengthy legal fight over groundwater contamination, Lodi has turned its focus to cleaning up the toxic chemicals that threaten its drinking water.

 

In an informational City Council meeting Tuesday morning, consulting firm Treadwell & Rollo outlined the processes by which the chemical perchloroethylene, also known as PCE, will be extracted from the soil and groundwater in five city plumes over the next 50 years. The cost estimates approach $50 million.

 

Lodi has spent the past eight years in a legal tussle with insurance carriers for businesses that dumped toxic industrial cleaning chemicals down leaky city sewer pipes, contaminating soil and groundwater decades ago. Lodi has received $24 million in net settlements to help pay for the cleanup and repay city costs. Water rates in the city were increased to make up the difference.

 

With the legal battle out of the way, consultant Phil Smith said contractors will begin installing pumping equipment in the so-called Central Plume, and aggressive cleanup will begin in 2009.

 

"In August, we'll have a public meeting for input, and we'll have information available for people," Smith said.

 

Hydrologist Patrick Hubbard outlined the methods by which PCE can be effectively cleaned out of the city's groundwater.

 

The first method is called soil vapor extraction, a process by which the chemical vapors are essentially vacuumed out of the soil.

 

Hubbard said soil vapor extraction has been tested at some groundwater wells in Lodi, and close to 13,000 pounds of PCE has been pulled from the soil thus far.

 

The second method is to pump water out of the ground and send it through filters that contain carbon or another material like carbon. The carbon attracts and holds the toxic chemicals, while allowing clean water to flow through, Hubbard said.

 

"Both methods are tried and true," Hubbard told the council. "We'll extract large amounts of PCE at first, and the amounts will diminish over time."

 

A third method, called air stripping, is being studied by the firm. The air stripping process aligns water in a column, allowing it to be cascaded through beads - much like a waterfall. Hubbard said the process allows oxygen to break the bonds between water and chlorine, releasing the chemicals to evaporate into the air.

 

"It's like at your pool, when you get that chlorine smell," he said.

 

Vice Mayor Larry Hansen said he feels confident Lodi is attacking the cleanup process the best way it can.

 

"Our legacy is going to be clean water for our residents," Hansen said. "That's the driving force behind all of this."

 

One resident, Jim Wiatley, approached the council regarding a personal well he uses at his Almond Drive home, close to an existing plume.

 

Smith and Hubbard said they will help him to take the steps necessary to ensure his water quality.#

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