The La Jolla Development Permit Review (DPR) subcommittee heard details last week about the removal of an existing gas station at the corner of Eads Avenue and Pearl Street, where the property owner hopes to develop a mixed-use, residential-retail project.
Questions about potential migration of soils contaminated by gasoline and other petroleum products were raised during last month’s DPR meetings, where the project was first presented by architect Alex Faulkner and land use and planning consultant Joe LaCava.
Chuck Houser, an environmental consultant and hydro-geologist (one who studies the distribution and movement of groundwater in soil and rocks of the Earth’s crust), offered a presentation on the proposed cleanup, fielding questions from DPR trustees and attendees.
Some petroleum hydrocarbons (like those found in oil-based products) are naturally occurring in the Earth’s subsurface, he said.
Whether natural or having seeped into the ground from gas tanks or the existing service station, Houser said they will be monitored during excavation for the underground garage.
“This is not rocket science,” he said. “We can keep very good control of what’s going on.”
Though Houser said it is “highly likely” work crews will encounter contaminants during the process, he said the majority of them would probably be hydrocarbons with low volatility and migration levels.
“Oil is far less of a potential health risk then diesel, which is far less than gasoline,” he said, adding that bacteria in the soil naturally eat away some hydrocarbons.
“A community health and safety plan is part of the property mitigation,” Houser said, assuring that his crew would have an on-site lab to monitor any hydrocarbon vapors or dust that might be pushed into the air during excavation.
A notice about the work will be delivered to residents in the immediate vicinity, and crews will also test for the presence of lead.
“We’ll analyze until we’re not detecting it,” he said. “My cell phone number is going to be on that notice, so if a neighbor in the area is concerned about something they see or smell, I get a phone call and I will deal with that.”
Any contamination in the subsurface will be cleaned up and removed to the lowest point of the garage, he said.
If it is believed contamination exists below that level, it will be noted in county reports that will be available online.
The consultant must demonstrate to the county that any remaining hydrocarbons will not present a risk to adjacent homes.
“We give them recommendations, and they evaluate those recommendations,” Houser said. “The county wants a less than one-in-a million-chance that someone’s going to get sick.”
Houser said the water table is about 30-feet below the surface, and that the excavation would not get “anywhere near close to that.”
He said the soil would be taken to a disposal facility in Otay Mesa, or it could be heat-processed elsewhere and used as ground cover at a landfill.
DPR chair Paul Benton said city and county geologists will review the cleanup process, and raise their own questions.