PG&E removing long-ago contaminated soil from Oakdale site

Not many locals remember when a plant on West J Street produced gas for cooking, lighting and keeping people warm in their homes.

What’s called a manufactured gas plant was operated there from 1913 to 1930, using coal and oil to make fuel before the arrival of natural gas pipelines. The Oakdale gas plant was totally dismantled by 1945, but the toxic residues that remain are a concern for state and federal regulators.

For the next five months, Pacific Gas & Electric Co. will remove contaminated soil from the site in a significant cleanup operation. About 950 truckloads of dirt will be excavated at the PG&E Service Center at 811 W. J St., across the street from the Oakdale High School campus. The service center will remain open during the cleanup.

PG&E acquired the old gasworks in 1928 and established the service center on the same 3.7-acre site in the 1930s. According to a PG&E history, the gas plants throughout California and the United States made gas for street lamps and for business and household needs. Byproducts including coal tar and soot were either hauled away for disposal or remained on site.

The California Department of Toxic Substances Control says the Oakdale site has soil contaminated with polycyclic aromatic hydrocarbons, petroleum residue and metals.

The contamination at the service center is capped by concrete and asphalt, which needs to be broken up before 14 feet of soil underneath is excavated.

“There is no indication the former plant site poses any health concerns,” PG&E spokeswoman Brandi Ehlers said. “We did a human health risk assessment and determined there was no significant risk to on-site workers or nearby residents.”

A fence was put up and equipment was brought in this week to begin the cleanup project, which is expected to continue until May. The work includes a survey for underground lines, followed by asphalt and concrete removal, and construction of a retaining wall to support the excavation area. After the tainted soil is hauled off, workers will backfill the area with clean soil and pave over it.

The operations are scheduled from 7 a.m. to 5 p.m. Monday through Friday. During the busiest time, two or three trucks will enter and leave the site every hour. A state notice said the activity will be coordinated with school bus schedules and peak traffic around the high school.

More than 40 manufactured gas plant sites formerly owned or operated by PG&E are in different stages of voluntary remediation, the company says. Typically, the plants were centrally located in cities to serve business and residential customers. Most were closed and demolished before World War II.

In the 1980s, the Environmental Protection Agency documented more than 1,500 former plant locations across the country and discovered many sites were contaminated. State regulators followed the EPA study with soil and groundwater testing at former gas plants in California.

According to reports, investigations at the Oakdale site since 1986 have found tainted soil as much as 60 feet below ground level, but no impacts on groundwater.

PG&E says it removed some tainted dirt beneath landscape beds at the service center and cleaned a neighboring property four to five years ago. A small area next to an Oakdale High athletic field across the street was remediated in summer of 2012.

Manufactured gas plants were operated in other cities in the region.

PG&E gives an inactive cleanup status to the former gasworks at Ninth and D streets in Modesto that occupied an entire block. Synthetic fuel gases were produced from 1911 until 1930, when natural gas became available for local customers. The plant was on standby until 1945 and then was demolished, a report says.

In Turlock, more than 22,000 tons of tainted soil were removed in 2008 from a former plant site at 650 S. Golden State Blvd., a closeout report says. The state and Southern California Gas Co. agreed in 2003 to look for contamination and found hydrocarbons, volatile organic compounds, cyanide and heavy metals.

Regulators decided a small amount of groundwater contamination did not need to be addressed.

During the Oakdale cleanup, the public can report problems with dust, odors and other issues to PG&E by calling (866) 247-0581.

This story was originally published January 8, 2015 at 10:20 AM with the headline "PG&E removing long-ago contaminated soil from Oakdale site."