The Department of Toxic Substances Control (DTSC) invites public input on a proposed cleanup plan to address contaminated soil and gas deposits at the former Hi-Tech Cleaners Site located at 3417 W. Slauson Ave., in Los Angeles. A public meeting is scheduled from 6:30 to 8 p.m. July 17 at the U.S. Bank community room, 5760 Crenshaw Blvd., in Los Angeles.
The plan, called a draft Removal Action Workplan (RAW), describes in detail the environmental studies conducted, results, and proposed cleanup activities at the site, which spans approximately 7,000 square feet. It is currently a vacant lot located in a mixed residential and commercial area. The report reveals that so-called “sensitive receptors” (e.g. residences and schools) are nearby. A dry cleaner formerly operated at the location from 1999 to 2014.
The current property owner, the Los Angeles County Metropolitan Transportation Authority (Metro), has conducted environmental investigations at the site under DTSC’s oversight since 2017. Site investigation activities found that tetrachloroethene (PCE), a chlorinated volatile organic compound (CVOC), has impacted the soil and gas at the Site and neighboring properties.
PCE is a solvent widely used in dry cleaning and metal degreasing. It is known to pose a threat to human health and the environment. Trichloroethylene (TCE), a breakdown product of PCE, is also considered a chemical of potential concern. To ensure the safety of human health and the environment, DTSC is requiring cleanup activities.
The Draft RAW was submitted by TRC, consultants for Metro. It concluded that:
—Elevated levels of CVOCs were found in soil gas samples
—No groundwater was found as of 190 feet below ground surface. Therefore, groundwater was not addressed.
As a result of these findings, the draft RAW reviewed three alternatives for cleanup:
1) Natural biodegradation. This is a naturally occurring process in which microorganisms, such as yeast, fungi, and bacteria, break down target substances, like fuels and chlorinated solvents, into less toxic or non-toxic substances.
2) Excavation (soil removal). This entails the physical removal and treatment or disposal of affected soil. Contaminated soil is removed using standard construction equipment, like backhoes and excavator track hoes.
3) Soil Vapor Extraction. Vapors are the gases that form when chemicals evaporate. The Soil Vapor Extraction (SVE) system removes vapors from the soil by applying a vacuum to pull the vapors out. The vacuum pulls air and vapors through the soil and up the well to the ground surface for treatment.
The draft RAW proposes to install and operate a SVE system to address the elevated concentration of CVOCs in soil gas. A pilot SVE study was performed in February 2018 and was determined to be effective. Following the startup of the SVE, soil gas concentrations will be monitored to determine its effectiveness.
