Stalking the Wild FeOB

March 11, 2006. It was a dark and stormy night. No, that's a lie. It was a sunny morning, calm, and unusually warm for mid-March. Six of us met at Tall Timbers Marina, loaded dive gear into the IMH research boat Roper, and set forth upon the mighty and beautiful Potomac River to hunt the elusive iron-oxidizing bacteria (FeOB) on a steel shipwreck near the Piney Point oil terminal. The FeOB is a nasty little beast. It eats shipwrecks — but we were ready for it, armed with sample tubes and collectors. Our fearless team included Dr. Susan Langley, the Maryland state underwater archaeologist; Project Chief Scientist Todd Plaia, a microbiologist from American Type Culture Collection (ATCC), a non-profit biological research institution in Manassas, Virginia; Brian McMillan and Ted White, volunteer divers from Adventure Scuba in Chantilly, Virginia; and Dr. Richard V. Ducey and David Howe, IMH volunteers. The wreck may be part of the tank barge STC 410 which exploded at the terminal on December 20, 1986, while discharging a cargo of JP-4 jet fuel for Naval Air Station Patuxent River. Nicknamed "the Puzzle Pile," the wreck stands 19 feet tall in 60 feet of water. It was found in 2002 by the NOAA survey vessel Bay Hydrographer, and consists of a confused jumble of heavy steel plates and pipes. We "live-boated" the dives. Susan and Dave stayed dry to handle the boat and marker buoys and to tend the divers as they cheated death for science. 311feob.jpg

The first two sets of dives were made in moderate current on a flood tide. We missed the wreck both times, probably because the marker buoy dragged despite two 10-pound mushroom anchors. The third set of dives was successful. Brian and Ted made the first dive of that set. They reconnoitered the site, tied and blew a small lift bag on the wreck as a second marker, and collected samples of ambient water and existing rust on the structure. After they surfaced, Todd and Rick made the second dive and placed six FeOB collectors on the site. Each collector carries three small plates of a known alloy of new iron. They will be recovered and analyzed after a measured period of immersion — whenever Todd says and the weather allows. The water salinity was determined by a refractometer to be 15 parts per thousand, about half the typical salinity of seawater. The water temperature was 46° F (7.8° C) on the surface. Visibility was typical for the Potomac: several feet on the surface, and several inches near the bottom. Analysis of the samples will take some time. We will post the results. Still, it was an excellent start to the 2006 diving season. Six hours on the water, Todd got what he wanted, and everyone who wanted to get wet got wet.