On Thursday, July 24, 2003, the U.S. Coast Guard (USCG) notified the U.S. Environmental Protection Agency (USEPA) of a toxic chemical release aboard the cargo ship Axel Maersk. The USEPA mobilized an OSC and the Superfund Technical Assessment and Response Team (START-2) to the site to assist in identification and containment of the release on the Axel Maersk.
The Axel Maersk is one of the largest container ships in the world. Built in 2002, it is 1,154 feet long, 140 feet wide and capable of carrying over 3,000 shipping containers. It arrived at the Port of Tacoma for the first time at approximately 6:00 AM on Thursday. Immediately upon arrival, longshoremen began unlashing cargo containers for unloading. During this process there was a release of toxic vapors and six longshoremen and one of the crewmembers were exposed to the unknown chemical. They displayed symptoms such as nausea, vomiting and chest pain. These personnel were taken to local hospitals, where they were treated and released by early afternoon.
The Tacoma Fire Department’s (TFD) Hazardous Materials Team and the Maersk Sealand emergency response contractor, Foss Environmental, responded to the reported release. At approximately 8:44 AM, the Incident Command was established at the terminal, headed by the Tacoma Fire Department. Other members of the Incident Command included the U.S. Coast Guard and APM Terminals. Upon establishing the Incident Command the Coast Guard Vessel Traffic Service closed Sitcum Waterway to all commercial vessel traffic as a precautionary measure.
At approximately 2:20 PM, the TFD Hazardous Materials Team, having found no indications of chemical vapors aboard the ship, transferred Incident Command to the U.S. Coast Guard and demobilized. The USCG requested the support of the USEPA. The response OSC and START-2 mobilized to the site to assist in finding, isolating and containing the source of the hazard to prevent any further release to the environment. Immediately upon arrival at the site, START-2 began to assist Foss Environmental with air monitoring of dock areas and waterways near the Axel Maersk. By late afternoon, the USCG reopened the Sitcum Waterway to commercial vessels and cleared the adjacent dock areas to resume work under the advice of an industrial hygienist, Foss Environmental and the USEPA.
Once the extent of contamination was narrowed to the ship, the priority of effort shifted to the hazardous materials containers stowed on decks 17 and 19. Foss Environmental and START-2 executed a reconnaissance of these decks and unlashed all containers adjacent to the bulk hazardous liquid tanks stowed there. During this reconnaissance START-2 was monitoring for organic vapors with a photo-ionization detector/flame-ionization detector and found nothing above background levels on either deck. Foss Environmental and APM Terminals began to unload containers from decks 17 and 19 to uncover the suspect bulk liquid containers of t-dodecyl mercaptan, 2,6-di-tert-butylphenol and stabilized acrylic acid. START-2 performed continuous air monitoring on deck and Foss Environmental inspected the containers unloaded to the containment area on the dock for leaks with a photo-ionization detector (PID).
At approximately 12:10 PM on Friday, July 25, 2003, Foss Environmental located staining near an over-pressure valve, the possible evidence of a release, on a t-dodecyl mercaptan tank on the ship. Mercaptan is a volatile flammable liquid commonly used as an additive in natural gas to give the odorless gas its signature smell. START-2 took a small sample of a clear liquid near the staining for analysis in the portable gas chromatograph/mass spectrometer (GC/MS) and attempted to confirm the presence of organic vapors around the leak with a PID. Both instruments returned negative results. Additional air samples were collected in tedlar bags from around the suspect container and analyzed with the GC/MS. A direct reading Draeger CMS with a mercaptan chip and an acrylic acid chip was also used to attempt to detect either substance from around the suspect container. Again, both instruments returned negative results.
The suspect container was removed from the ship at approximately 5:30 PM and taken to the Port of Tacoma’s hazardous materials containment area for further inspection. Foss Environmental conducted additional visual checks of the container while monitoring with a PID. START-2 continued air monitoring aboard the Axel Maersk, near where the suspect container had been stowed. At 8:50 PM, Foss Environmental reported seeing two small liquid leaks around the bulkhead supports. More liquid and air samples were taken for analysis with the GC/MS. All samples were below detection limits during analysis. The suspect container was wrapped in plastic sheathing and declared as frustrated cargo.
In an effort to declare the ship completely safe for work to resume, the USCG wanted to ensure that the cargo holds below the deck were not filled with a pool of mercaptan vapors, which are heavier than air. The below-deck ventilation system was turned on and the exhaust vents were monitored with a PID and air samples were taken for GC/MS analysis. The PID did not register above background levels and the GC/MS results were below detection limits. Based upon the analytical results, the USCG determined that the ship was safe for work to continue. Based upon the condition of the suspect container, it was inferred that the vapor pressure in the container headspace had exceeded the settings of pressure release valve and the container had released mercaptan vapors, relieving the internal pressure, and then resealed. The minute amount liquid sample collected from the container was assumed to be water condensation leaking out from between the tank and the insulation.
Maersk and APM Teminals will move the container to a quarantined area on the dock for recertification. Work on the Axel Maersk will resume and ship will be free to depart the Port of Tacoma once all cargo has been transferred.
The vessel is expected to depart the Port of Tacoma Sunday, July 27, 2003 at 8:00 AM.
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