Swabbing of SF Bay dredging paths begins

Dec. 27, 2007

SAN FRANCISCO – Beginning tomorrow, crews will be swabbing parts of the bottom of San Francisco Bay where dredging occurs to look for obvious contamination as a result of the Cosco Busan oil spill.

Though monitors were put on dredges immediately after the oil spill incident as directed by the Corps of Engineers and DMMO - Dredge Material Management Office - agencies to observe for any indications of contamination, the swab tests will provide a clearer picture of what’s on the bottom of the bay along the paths of remaining dredging to be conducted this winter.

“The results will help us develop a plan to deal with Cosco Busan contamination should we discover any,” said Arijs Rakstins, Chief of Programs and Project Management for the San Francisco District, U.S. Army Corps of Engineers.

“Fortunately, the oil spill happened near the end of the 2007 dredging season so there was little impact to operations,” he added.

The test consists of dragging oil absorbent pom poms along the bottom of areas of the bay proposed for dredging. Crews then conduct a visual and smell test to determine whether further chemical tests will be necessary.

It is still uncertain how the oil globules may be interacting with the movement of bay sediments. The largest concentrations of oil may have already washed ashore or dissipated, or may still be on the bottom of the bay traveling with tidal currents.

Oil may also have attached itself to silt and be heavy enough to come to rest in the deepest parts of the bay.

The Corps and DMMO agencies, as well as many other concerned organizations, are continuing to study the material and sharing integrated scientific information to better understand how to deal with the substance in a safe manner.
“It is unlikely we will find any traces of oil during the initial tests,” said Rakstins. However, the worst case scenario is that our current dredging projects may be delayed to accommodate further testing. Also, removal of contaminated dredge material could result in additional costs and time.

Ultimately, the Corps and DMMO agencies are working hard to develop the most effective solution to protect the bay’s ecology while minimizing the impacts to future dredging projects.

The DMMO is the Dredge Material Management Office, and is a joint program of the San Francisco Bay Conservation and Development Commission, San Francisco Bay Regional Water Quality Control Board, State Lands Commission, the San Francisco District U.S. Army Corps of Engineers, and the U.S. Environmental Protection Agency.

Also participating are the California Department of Fish and Game, the National Marine Fisheries Service and the U.S. Fish and Wildlife Service who provide advice and expertise to the process.  The purpose of the DMMO is to cooperatively review sediment quality sampling plans, analyze the results of sediment quality sampling and make suitability determinations for dredged material proposed for disposal in the San Francisco Bay region.

The Corps’ San Francisco District operation and maintenance program includes dredging projects totaling 4.5 million cubic yards annually, of which 1.5 million cubic yards come from the San Francisco Bay navigation channels. Much of this dredging is necessary to maintain navigation by keeping the depths of the bay at an acceptable level for recreational and commercial vessels to enter the ports.