CHARLESTON, S.C. - The state agency in charge of redevelopment at the old Charleston Naval Base has signed an agreement to protecting future property owners from liability for any leftover pollution.

The Charleston Naval Complex Redevelopment Authority voted unanimously Tuesday to enter a voluntary cleanup contract with the Department of Health and Environmental Control that covers about 500 acres that have not yet been transferred from the federal government.

The Navy already has spent about $70 million to clean pollution on the property.

The deal is designed to protect future owners from liability once base property is turned over by the federal government.

The only time a future owner would be liable is if DHEC determines the new owner, and not the Navy, created the environmental problem or disturbed any safeguards the Navy may have put in place.

Jim Bryan with the Redevelopment Authority said the agreement will cover the land after it is transferred to North Charleston and the State Ports Authority.

Most of the base property is covered under similar agreements, officials said.