PCBs

Shaw Environmental took 71 samples to check for cancer-causing polychlorinated biphenyl compounds, or PCBs.

Of those, 23 contained more than 50 parts per million of the toxins. Anything above that level has to be incinerated. Seventeen samples had less than that amount, meaning those can be treated and sent to a landfill.

Any PCBs will have to be pumped or placed into small drums and removed, if possible. If they cannot be removed because of the ship's layout, Shaw recommends encapsulating them.

The most likely sources of the PCBs were fire retardants sprayed throughout the Yorktown decades ago.

Anchored in pluff mud, the 70-year-old aircraft carrier Yorktown poses no imminent environmental threats to the public or Charleston Harbor, a study released Wednesday shows.

By the numbers

Yorktown at Patriots Point:

70 Years old

38 Years at Patriots Point

$4.4 million Estimated environmental cleanup cost

509 Number of tanks surveyed

129 Number of tanks contaminated

160,000 Number of gallons of petroleum residue

1.6 million Number of gallons of affected water

$81 million Estimated overhaul cost of entire ship

Shaw Environmental Inc. told Patriots Point's board of directors the World War II-era ship — moored as a museum ship since 1975 — will have to be cleaned extensively before structural repairs can take place. The estimated cost is $4.4 million and will take about six months.

Patriots Point officials plan to apply for federal funding to help with the cleanup, and they hailed the report as good news.

“There are no leaks, no threats to the harbor and the integrity of the vessel is in good shape,” board Chairman Ray Chandler said. “All of these things bode well.”

Board member Eddie Taylor pointed out that the report shows no emergency situation, giving Patriots Point time to secure funding and perform cleanup ahead of much- needed structural repairs.

“The great news is the people who visit or stay on the boat are in no danger,” said Mac Burdette, Patriots Point executive director.

The Atlanta-based firm found 129 tanks with about 160,000 gallons of petroleum residue and 1.6 million gallons of onboard contaminated water.

Just two of 21 refrigeration units are charged, and all firefighting systems were found to be drained or air-gapped.

Shaw also found varying levels of cancer-causing polychlorinated biphenyl compounds, or PCBs, in 40 out of 71 samples it took around the ship.

Most hydraulic systems were found to be empty, and all radiological devices are low-level and pose no risk to anyone, the firm said in the report.

Any radiological devices could be put in containers and disposed of in a low-level facility.

To remove fluids, Kenyon recommended pumping and separating petroleum products and affected waters.

State-owned Patriots Point Naval and Maritime Museum is staring at an estimated $81 million price tag to upgrade the aging vessel that has served as the centerpiece attraction for tourists since it was decommissioned and brought to Charleston Harbor 38 years ago.

The environmental assessment of the ship comes before a structural analysis is conducted to determine the ship's overall condition.

It could take decades to refurbish the ship, since Patriots Point's annual income is about $9.5 million.

Reach Warren L. Wise at 937-5524 or twitter.com/warrenlancewise.