The distribution of sediments in the Bay is uneven. Tidal channels are scoured by currents and make up the deeper parts of the Bay. Oil tankers and other large ships that move in and out of the Bay need deep water and can often be seen anchored in the deeper channel areas. Ports such as Oakland Port, where container ships are loaded and unloaded, are at the shallow edges of the Bay where water depths are extremely shallow. Ports must therefore dredge sediment to create channels that lead to the loading areas adjacent to land.
Where to place sediment that has been dredged from shallow areas near ports is a large problem. A dumping site near Alcatraz Island has become a large mound that is a hazard to ships traveling on the Bay. Offshore sites have been identified on the continental shelf west of San Francisco, but transporting sediments to these areas is very expensive. In some cases, sediment is highly contaminated by substances such as PCB or DDT, that are a result of industrial activity around the Bay. These toxic sediments cannot be dumped anywhere in the ocean, but must be disposed of in upland sites, often in other states of the U.S. Understandably, other regions are not anxious to receive the contaminated products of our economic activity.
Click here to read an article from the San Francisco Examiner about opposition to sediment disposal of contaminated Bay sediment in Arizona.
1. Summarize the issues discussed in this article.
Click here to read an article from the San Francisco Chronicle about proposals for dealing with sediment dredged from port channels.
2. Summarize the issues discussed in this article.