PWSRCAC: Oil contaminants in PWS, GOA at all-time low

Report credits Alyeska’s efficiency in operating ballast water treatment plants

A new study on long-term environmental impacts of operation of Alyeska Pipeline Service Co.’s Valdez Marine Terminal and associated tanker traffic concludes that oil contamination in Prince William Sound and the Gulf of Alaska is at an all-time low.

The report on 2018 samplings analyzed by Payne Environmental Consultants, of Encinitas, CA, notes that in recent years the petrogenic hydrocarbon inputs into Port Valdez from the Alyeska Marine Terminal and tanker operations have been declining as reflected in total polycyclic aromatic hydrocarbon concentrations in both sediments and mussels tested.

The study for the Prince William Sound Regional Citizens’ Advisory Council noted several changes over the years which the council said have contributed to a reduction in pollutants being discharged. These include the elimination of single-hulled tankers and Alyeska’s ability to effectively operate their Ballast Water Treatment Facility (BWTF), which removes oil contamination from tanker ballast water.

“The council’s long-term monitoring program helps fulfill one of our responsibilities under the federal Oil Pollution Act of 1990 and is one of the longest running studies of its kind,” said Donna Schantz, executive director of the council.

Through results of this study, efforts and commitment by Alyeska and the Trans Alaska Pipeline System shippers to reduce hydrocarbon releases into the waters of Prince William Sound and the Gulf of Alaska are recognized, she said.

Three types of samples were retrieved and analyzed from various locations for the 2018 study.

They included blue mussels, marine sediments and passive sampling devices, in the form of special plastic strips left in the water to which oil contamination can adhere. The samples were all chemically analyzed, followed by interpretation of data by environmental forensic scientists who can identify sources of oil contamination.

The passive sampling devices also provide water quality information relevant when considering the potentially toxic impacts of low levels of oil contamination on sensitive life stages of marine life, such as salmon and herring embryos, PWSRCAC officials said.

The 2018 monitoring was noteworthy for its geographic range of sampling. In most years the monitoring is limited to Port Valdez, but every five years the sampling locations are expanded throughout Prince William Sound and the Gulf of Alaska, largely following the path of the Exxon Valdez oil spill disaster of March 24, 1989.

The monitoring of Port Valdez focuses on assessing the environmental impacts of the Valdez Marine Terminal, while monitoring elsewhere is focused on assessing impacts of oil tankers, including possible lingering oil from the Exxon Valdez spill. Along with sites heavily oiled in March of 1989, monitoring was conducted, for comparison, at unoiled control sites.

The study notes that in 2016 and 2017 their forensics’ approach to tracking Alaska North Slope oil was improved by the collection and detailed analyses of effluent samples from the biological treatment tank at Alyeska’s Ballast Water Treatment Facility and recommended this testing as a recurring part of the annual program.

Detailed results of the PWSRCAC 2018 study are included in the report, “Long-term Environmental Monitoring Program: 2018 Sampling Results and Interpretations,” by James R. Payne and William B. Driskell of Payne Environmental Consultants.

Find the report online at pwsrcac.org/programs/environmental-monitoring/ltemp.