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BLM issues FONSI for ballast water treatment Bureau of Land Management says Alyeska’s proposal to modify Valdez ballast water treatment facility will reduce impacts Kristen Nelson Petroleum News
The Bureau of Land Management said Oct. 30 that Alyeska Pipeline Service Co.’s proposal to modify the ballast water treatment facility at the Valdez Marine Terminal is expected to reduce overall environmental impacts in the short and long term compared to current impacts of the facility in its existing configuration. “The long-term impacts are beneficial and positive, especially for air and water quality,” BLM said, in announcing a finding of no significant impact (FONSI), which the agency said will be signed at the end of November. The documents are available at www.jpo.doi.gov.
The ballast water treatment facility primarily treats dirty ballast water off loaded from marine oil tankers when they reach port, before they load crude oil. BLM said Alyeska proposed modifying the facility to accommodate reduced ballast water flow due to the use of double hulled marine tankers as required by the Oil Pollution Act of 1990 and less throughput of crude oil in the trans-Alaska oil pipeline.
BLM said modifications to the ballast water treatment facility are estimated to reduce release of benzene, toluene, ethyl-benzene and xylene to less than 1 ton annually. Current estimates of releases range from Alyeska’s estimate of 138 tons to the Environmental Protection Agency’s estimate of 208 tons.
A series of modifications will be implemented between 2006 and 2011.
The environmental assessment, released by BLM at the Joint Pipeline Office in Anchorage, said the proposal is in conformance with all applicable land use plans. BLM said the renovation of the ballast water treatment facility would significantly reduce the physical structure of the three-tier wastewater treatment process, incorporate new technologies, reduce the flammability of the storage tanks, improve operational efficiency, reduce operational changes due to lower ballast water flow rates and changing tanker fleet characteristics.
Facility designed for 30 million gallons a day BLM said the short-term objective of the modification is “to increase safety by reducing flammability in the ballast water and recovered crude oil tanks. The long-term objective is to completely enclose the secondary and tertiary water treatment systems” at the ballast water treatment facility. The facility was designed in the 1970s to treat and process an average of 30 million gallons of ballast water a day; the average daily flow in 2006 has dropped to 5 million gallons. All tankers must be double-hulled by 2014, and the double-hulled tankers servicing Valdez “use an offshore segregated de-ballasting system,” reducing the need for onshore ballast water treatment.
The primary water treatment system includes three ballast water storage tanks (the 90s tanks) and two recovered crude oil storage tanks (the 80s tanks). Alyeska proposes to connect tanks 93 and 94 to the terminal vapor control system and remove tank 92 from service and place it in standby mode.
In the 80s tanks, Alyeska proposes to mitigate “a flammable atmosphere risk” inside the tanks “by adding a temporary inert nitrogen gas blanket system for the short term.” In the long term the company will install pipe to connect the 90s tanks directly to the main terminal storage tanks; the two 80s tanks will then be removed from storage.
Secondary treatment system oversized In the secondary treatment system there are six dissolved air flotation cells. The system is oversized for the amount of effluent currently being processed and Alyeska proposes to remove two of the cells from service and eventually to replace the current dissolved air flotation cell system with an enclosed induced gas flotation system “that would contain current fugitive air emissions in a closed system.”
The tertiary water treatment system is a biodegradation process using aerobic bacteria with two biological treatment tanks for aerobic microbial consumption of dissolved hydrocarbons remaining in the water from the secondary system, BLM said. Alyeska is proposing to remove one water treatment tank from service to accommodate less ballast water flow and completely enclose the biological treatment tank splitter box. In the longer term the biological treatment tank system would be replaced with an enclosed chemical air stripper-carbon absorption process “that would contain current fugitive air emissions.”
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