The immediate concern is the extent of contamination from the Defense Personnel Support Center, near the Schuylkill Expressway, rather than Sun's own property, where the company is cleaning up other plumes of oil.
The base, Sun and the DEP have agreed on a need to pinpoint contamination in the area.
Goldberg said a drilling rig on a truck will sink between six and 12 wells in the area near the supply base, targeting the closest part of Passyunk Homes.
Although petroleum fumes in high concentrations can pose health or explosion problems, the DEP says no hazardous levels were found at Passyunk Homes or other residential areas.
Now the wells will probe 35 feet into the earth and see what's in the groundwater.
The city hopes to redevelop the supply base, which stands over an estimated 180,000 to 240,000 gallons of petroleum. The center, at 20th Street and Oregon Avenue, is moving toward a federal shutdown.
Some residents of Passyunk Homes and Packer Park have voiced anxiety about potential health risks.
Officials have noted the Passyunk Homes have no basements, which might provide an avenue for contamination.