On Monday, PG&E will begin a 10-month cleanup of a lot near downtown San Luis Obispo that contains century-old petroleum contamination.
The cleanup will be done at a lot on the corner of Walker and Pismo streets. An estimated 20,000 tons, or 900 truckloads, of contaminated soil to a depth of up to 20 feet will be removed.
The lot was the site of a manufactured gas plant operated by San Luis Gas and Electric Co. from 1905 to 1918. The facility used coal and oil to produce gas used by residences and businesses for lighting, cooking and heating.
“As was common practice at the time before environmental regulations were in place, some contaminated soil was left buried at the site when operations ceased,” according to the state Department of Toxic Substances Control in a public notice of the cleanup.
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PG&E owned the site several times after the gas plant shut down, buying the property in 1938 and selling it off in parcels in 1958. It repurchased the property in 2009 to conduct investigation and cleanup work.
“We volunteered to take care of this site in order to be good environmental stewards,” said Jeff Smith, a PG&E spokesman.
The pollutants on the site consist of various petroleum substances and toxic metals, such as arsenic and lead. Although excavation could go as deep as 20 feet, most of the contamination is in the top 5 to 6 feet of soil.
Work will begin with removal of trees and two vacant structures on the site — a large barnlike building and an old gasworks building. Excavation is expected to begin in late September. The city of San Luis Obispo and the county’s Air Pollution Control District have issued the necessary permits for the cleanup work.
The contaminated soil will be trucked to two disposal facilities outside the county that are licensed to take such waste. The site will be backfilled with clean soil, then graded and restored for redevelopment at a later date.
The property is one of numerous remediation sites PG&E is cleaning up throughout central and northern California.
“This one has attracted some public attention because it is adjacent to downtown,” the spokesman said.
An estimated eight to 10 trucks will enter and exit the cleanup site from 7 a.m. to 5 p.m. Monday through Friday. Flaggers will be on-site to manage truck, car and pedestrian traffic.
Trucks will follow a city-approved route from Walker Street to Higuera Street to Marsh Street and then onto Highway 101.
The utility is taking a number of steps to protect public health during the cleanup when the contaminated soil will be exposed to the environment. Those include various dust, odor, noise and vibration control measures and covering trucks with tarps before they exit the site. PG&E conducted a health assessment of the site and determined that the cleanup will not pose a public health risk, the spokesman said.
The cost of the cleanup is about $12 million, he said. A portion will be paid by PG&E shareholders and a portion through general rates.
Anyone with concerns or questions about the cleanup can call a PG&E response line at 866-247-0581.