SAN FRANCISCO (Map, News) - To determine whether the radioactive landfill at the former Hunters Point Shipyard will be replaced or paved over before it is given to San Francisco, the Navy has bored wells into the most contaminated parts to test groundwater pollution.

The 503-acre decommissioned Navy site in The City’s southeast area is slated to be developed by homebuilding giant Lennar Corp. The former shipyard is divided into land parcels and Parcel E-2, located at the southeast corner of the site, is the most contaminated parcel, according to Saul Bloom of Arc Ecology, which was contracted by The City to research and share environmental information about the Superfund site.

Parcel E-2 was used in the 1950s and 1960s by the U.S. Navy as a dumping ground for radioactive waste, construction debris, paints, solvents, woodchips and other materials, according to Bloom. A “landfill cap” was placed over 13 acres of Parcel E-2 in 2001 to help extinguish an underground fire that burned for six months and released toxic gases, according to information published by Arc Ecology.

Caps, which are less expensive than other methods of treating polluted land, can be cracked by earthquakes, by the natural heating and cooling of the earth, and by burrowing animals, according to Bloom.

The Navy is considering capping Parcel E-2 before it’s sold to The City, according to Navy Base Closure Manager Doug Gilkey. He said caps typically consist of soil, although gravel and asphalt can also be used.

The parcel might instead need to be excavated, Gilkey said.

Navy Remedial Project Manager Mark Walden said pollution could also be treated by injecting material into the groundwater. Such material fosters the growth of microbes that break down pollution, he said.

Groundwater tests scheduled next week will provide data to help the Navy and city decide which type of treatment is needed for Parcel E-2.

Test results will be included in a draft Parcel E-2 study due out in August, according to Gilkey.

Lennar spokesman Sam Singer said parkland is expected to eventually be built over Parcel E-2, and a roadway will run above the parcel or next to it.

Lennar has started to develop Parcel A, a 75-acre piece of land transferred from the Navy to The City in 2004 after environmental remediation work was completed. The first Parcel A homes are expected to be built by 2010, according to Singer. Another parcel has been proposed for a potential stadium for the San Francisco 49ers.

Parcel E-2 groundwater tests will be discussed at a public meeting scheduled for 6 p.m. today at the Southeast Community Facility, located at 1800 Oakdale Ave.

jupton@examiner.com