The Observer, January 2007

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Alyeska Viewpoint: Progress report on upgrades to ballast water plant

By Tom Stokes, Valdez Marine Terminal manager

Tankers arrive each week at the Valdez Marine Terminal to transport crude oil from Prince William Sound to refineries on the West Coast. Upon arrival, some tankers offload ballast water that has been used to control buoyancy. Many of the older style tankers do not have the ability to segregate ballast. In these ships, the ballast becomes contaminated with remnants of oil previously carried in the tanks and must be processed at the terminal’s Ballast Water Treatment Facility. The newest generation of tankers generally keeps the seawater ballast segregated from the oil tanks. The double-hulled tanker configuration required by the Oil Pollution Act of 1990 results in dramatically less ballast needing treatment. Therefore, the existing ballast water treatment system is now over-sized for the current and forecasted needs. In addition, Alyeska has set goals to reduce air and water emissions and improve worker safety at the facility. Alyeska has already started to implement its major project to completely renovate the ballast water treatment system.

The process currently involves a three-part treatment that plays off the natural tendency of oil and water to separate. The first step occurs in the 90s “settling” tanks where most of the oil is skimmed off the top. Recovered oil is then transferred to the 80s tanks and clarified water is charged from the 90s tanks to the Dissolved Air Flotation system.

The second step occurs in the dissolved air flotation chambers where air bubbles are pushed through the water to carry most of the remaining oil to the surface. The oil is then collected and combined with the other recovered crude.

The third step is in the biological treatment tanks where nutrients have been added to support the microbes that eat the water soluble hydrocarbons. The treated water is then discharged into Port Valdez.

The plant was originally designed and is permitted to process 30 million gallons of ballast and storm water per day.
Today, we are operating in the 2 to 4 million gallon per day range, and as new tank ships enter the system, the volume of water to be treated will continue to decline.

During 2006, we accomplished a number of steps toward our safety, environmental, and operational goals. We completed the risk analysis identification, evaluation and administrative mitigation controls. We completed the major studies to characterize and quantify the air emissions from the facility and continued to work with the Environmental Protection Agency and the citizens’ council to evaluate these emissions. We implemented several operational changes and project modifications that reduced the plant footprint by about one-third. This reduction provided significant reductions in our air emissions and increased worker safety. We also continued extensive conceptual and design engineering that included a proof-of-concept vapor line installation; installation of a nitrogen blanket to inert the atmosphere in tank 80; and a pilot test of equipment being considered for use in the renovation.

Moving into 2007, vapor controls will be installed on the ballast water tanks, up to three pilot plants and studies are being done to assist in evaluation of technologies for use in replacing the current treatment systems. The resulting information is being utilized to move from conceptual to final engineering and subsequent construction and installation. The changes are substantial and will result in a dramatic reduction in air emissions. We are committed to continuing the extensive project engineering and plant modifications to bring the ballast water facility into the future. The updated plant will provide additional protection for our workers and the environment while processing the necessary ballast water as part of the system.