Orange County health officials told ARCO/BP to dig out the contaminated soil and groundwater at Seal Beach gas station on Pacific Coast Highway in a Tuesday, Aug. 10 letter.
“Please begin work to obtain all necessary permits and access agreements immediately and notify this office with expected approval dates for each as soon as possible,” the letter said.
The letter from the Orange County Health Care Agency said excavation, commonly known as “dig and haul,” was the “most appropriate” alternative to cleaning up the site of the gas station. The underground storage tanks beneath the ARCO station have leaked at least twice since the 1980s. Last summer, evidence of gasoline vapor contamination was found in the soil beneath Bridgeport neighborhood homes near the gas station.
In the revised corrective action plan for the site, recently submitted by ARCO/BP, the petroleum company’s consultant recommended using electrical resistance heating to cook the contaminants out of the soil and ground water. ARCO officials have indicated they would be willing to excavate.
ARCO’s consultant has suggested that if excavation was used, the process should be supplemented with electrical resistance heating.
The letter was signed by Richard Sanchez, the health agency’s director of environmental health, and Anthony Martinez, senior engineering geologist for the agency.
However, Orange County officials recommended using “chemical oxidation” to supplement excavation.
Chemical oxidation, first proposed in ARCO’s draft corrective action plan, would use chemicals to remove the contaminants from Bridgeport soil.
“The public comments overwhelmingly support excavation as the primary remedial alternative,” the Sanchez-Martinez letter said.
The letter pointed out that the city of Seal Beach, in a letter authorized by the City Council, had also called for the “dig and haul” option.
“Upon review of the revised CAP, public comments and review of other technical documentation, the OCHCA determined that given the criteria of certainty, timeliness, and effectiveness, excavation was the most appropriate to address the majority of the contaminated source area,” the letter said.
The county health agency rejected electrical resistance heating as a supplement to digging and hauling, never mind as the primary treatment for the gas station site.
The Aug. 10 letter called electrical resistance heating “unacceptable for this site.”
“There is a potential for uncontrolled mobilization of contaminated vapors into adjacent commercial and residential buildings,” the Sanchez-Martinez letter said.
“High levels of methane in the subsurface, which ARCO/BP has stated are at least partially the result of utility line leakage, pose a potential fire and explosion risk,” the letter said.
The letter went on to say that ARCO/BP has no record of using electrical resistance heating at any of its clean up sites in California or anywhere else.
As for cleaning up the soil beneath the residential neighborhood, the county considers “dual-phase extraction” to be acceptable.
The OC Health Care Agency gave ARCO/BP until Sept. 30 to submit a work plan for the excavation phase of the cleanup project.
