Issues of Environmental Management in the Gulf of the Farallones 



Search for Containers of Radioactive Waste on the Sea Floor 



Herman A. Karl 



Between 1946 and 1970, approximately 

 47,800 large containers of low-level radio- 

 active waste were dumped in the Pacific 

 Ocean west of San Francisco. These con- 

 tainers, mostly 55-gallon drums, were to 

 be dumped at three designated sites in 

 the Gulf of the Farallones, but many were 

 not dropped on target, probably because 

 of inclement weather and navigational 

 uncertainties. The drums actually litter a 

 540-square-mile area of sea floor, much 

 of it in what is now the Gulf of the Far- 

 allones National Marine Sanctuary, which 

 was established by Congress in 1981. 



The area of the sea floor where the 

 drums lie is commonly referred to as 

 the "Farallon Islands Radioactive Waste 

 Dump." Because the actual distribution 

 of the drums on the sea floor was 

 unknown, assessing any potential environ- 

 mental hazard from radiation or contami- 

 nation has been nearly impossible. Such 

 assessment requires retrieving individual 

 drums for study, sampling sediment and 

 living things around the drums, and directly 

 measuring radiation levels. 



In 1974, an unmanned submersible was 

 used to explore a small area in the 

 Farallon Islands Radioactive Waste Dump, 

 but only three small clusters of drums were 

 located. Two years later, a single drum was 



retrieved from this site by a manned sub- 

 mersible. However, use of submersibles in 

 this type of operation is highly inefficient 

 and very expensive without a reliable map 

 to direct them. 



In 1990, the U.S. Geological Survey 

 (USGS) and the Gulf of the Farallones 

 National Marine Sanctuary began a coop- 

 erative survey of part of the waste dump 

 using sidescan sonar a technique that uses 

 sound waves to create images of large areas 

 of the ocean floor. Because of limited time 

 and funding, the survey only covered about 

 80 square miles, or 1 5 percent of the waste 

 dump area. 



Expert skills are required to distinguish 

 waste drums and other manmade objects 

 from natural geologic features or acoustic 

 noise on ordinary sidescan-sonar images 

 produced onboard ship. USGS scientists 

 developed new techniques for enhancing 

 the sidescan-sonar data from the Farallon 

 Islands Radioactive Waste Dump to detect 

 waste drums more easily and to distinguish 

 them from other targets with a high level 

 of confidence. Using these techniques, it 

 was also possible to differentiate real tar- 

 gets (drums) from acoustic noise. 



The enhanced images from the survey 

 showed the locations of many objects that 

 the scientists interpreted to be radioactive 



waste containers. In 1994, the USGS, the 

 Marine Sanctuary, and the U.S. Navy used 

 the Navy's DSV (Deep Submergence Vehi- 

 cle) Sea Cliff and unmanned Advanced 

 Tethered Vehicle (ATV) to verify these 

 interpretations by direct observation of the 

 sea bottom. The previous attempts in the 

 mid-1970's to locate waste drums in the 

 Gulf of the Farallones using submersibles 

 had been like trying to find a needle in a 

 haystack and had little success. 



Using the enhanced sidescan-sonar 

 images as guides, Sea Cliff and ATV were 

 able to "drive" directly from one suspected 

 drum site to the next. In every instance, 

 waste containers and other physical features 

 were found where the enhanced images 

 showed them to be, and no containers were 

 found where they were not indicated. 



This was the first successful test of 

 locating barrels by regional mapping and, 

 in that regard, represents a breakthrough. 

 By using the new USGS maps to detect 

 suspected barrel sites and U.S. Navy tech- 

 nology to directly view the sea floor, many 

 barrels and other containers were found 

 during just a single 24-hour ATV deploy- 

 ment, and each DSV Sea Cliff and ATV 

 dive verified the predicted absence or 

 presence of barrels. Visual observations 

 revealed that the condition of the barrels 



ranged from completely intact to com- 

 pletely deteriorated. 



This work proved that enhanced sides- 

 can-sonar images are a cost-effective and 

 time-efficient method for locating relatively 

 small objects on the sea floor and could 

 be used to locate containers of hazardous 

 waste in other ocean areas, such as Boston 

 Harbor in Massachusetts and the Kara Sea 

 in the Arctic Ocean north of Russia. 



Besides being the site of a marine sanc- 

 tuary, the Gulf of the Farallones supports 

 a major commercial fishery. In the past, 

 fear of radiation contamination from leak- 

 ing drums in the "Farallon Island Radioac- 

 tive Waste Dump" has adversely affected 

 the market for fish caught in the gulf. In 

 1998, the actual impact of the drums on the 

 marine ecosystem began to be evaluated. 

 Preliminary results suggest that it is much 

 less than feared (see chapter on Measuring 

 Radioactivity from Waste Drums on the 

 Sea Floor). 



66 Issues of Environmental Management in the Gulf of the Farallones 



