An oil industry watchdog group is pushing for construction of a special treatment plant to kill invasive species in ballast water carried aboard oil tankers calling on Valdez to load North Slope crude.
The Prince William Sound Regional Citizens' Advisory Council believes ships could bring in nonindigenous fish, crabs or microorganisms that could take up residence in local waters and potentially harm native aquatic life or commercial and sport fisheries.
The group proposes that a new wing be added to the ballast water treatment plant at the Alyeska dock in Valdez. The main treatment plant would continue its job of cleansing tanker ballast of residual oil before the water is discharged into the Sound, while the new unit would eradicate organisms using ultraviolet or chlorine disinfection and a filtration system.
Ballast water gives tankers that are empty of oil stability as they travel through sometimes heavy seas.
Tankers calling on Valdez can carry two types of ballast, segregated and unsegregated. Segregated ballast is carried in tanks or compartments separate from the cargo holds, while unsegregated ballast is carried in the same holds that also can carry oil.
The volume of unsegregated ballast has dropped sharply in recent years as the tanker fleet has converted from single-hull to double-hull ships, which have segregated ballast tanks.
The fleet upgrade, ironically, has heightened the threat from nonindigenous species, as segregated ballast is simply pumped overboard upon arrival at Valdez, the RCAC says. Aquatic stowaways can't survive the oily unsegregated ballast.
The citizens' advisory council outlined its ideas for an onshore invasive species treatment plant in recent comments to the U.S. Coast Guard, which is proposing nationwide regulations to limit concentrations of living organisms in ballast discharges. The rules potentially could affect the tankers that run between Valdez and West Coast ports.
While onboard eradication systems or ballast exchange are the options getting the most attention, the RCAC argues the fastest and best way to guard against invaders in Prince William Sound is to expand the ballast treatment system at Valdez.
A retrofit of the plant "could be accomplished by 2012," the council told the Coast Guard.
Already, 15 nonindigenous species such as certain algae, sea squirts and shellfish have been identified in the Sound, the council said.
Invaders such as zebra mussels have caused hundreds of millions of dollars in damage in other U.S. waters such as the Great Lakes.
"While there may be other contributors to the nonindigenous species found in Prince William Sound, there is reason to believe that many of these invaders are being transported by crude oil tankers that take ballast water on at West Coast refineries, transport it to Alaska and discharge contaminated ballast into Prince William Sound waters when crude oil is loaded at the Valdez Marine Terminal," the council said.
Anil Mathur, president of Alaska Tanker Co., which carries oil for BP, said his ships already do ballast exchange.
Ballast exchange is when tankers pump out port ballast and take on fresh seawater while sailing north to Valdez. This can flush out living organisms, though it's not a fail-safe measure, the RCAC contends.
Mathur questioned the need for an onshore plant to rid ballast water of potential pests.
He said he's unaware of any "critters from the south" riding in on tankers and taking hold in the cold waters at Valdez.
By WESLEY LOY