Army Corps of Engineers San Francisco Bay Model
Robert Stevenson, US Army Corps of Engineers—January 11, 2003
By Dan Day, from the February 2003 newsletter
Photos provided by Mark Detterman
The Army Corps of Engineers’ Bay Model Visitor Center.
The NCGS opened its 2003 field trip season with a visit to the Army Corps of Engineers Bay Model in Sausalito on January 11th. The Model is a landmark in Sausalito, harkening back to World War II, when it was a warehouse in the Marinship Shipyard where Liberty Ships were built.
The guide for this exciting tour of the Bay Model was ranger Bob Stevenson. Bob is a native of Ohio who has a love of nature and the great outdoors. After receiving a degree in geology, he spent several years as a park ranger in the Rocky Mountains, Alaska, and the Hawaii Volcano Observatory before assuming his current role at the Bay Model Visitor Center.
Introduction and overview to the Bay Model led by Ranger (and geologist) Robert Stevenson, with a view of Richardson Bay.
Bob began the tour by taking the group to the dock in front of the Center where everyone could view Richardson Bay. He then explained the role of the Army Corps of Engineers in maintaining San Francisco Bay and its waterways. The ACE is responsible for shipping channels, docks, airport runways, and any structures that affect the Bay. It also removes debris from Bay waters using two scavanging vessels docked at the site. Shortly after the attack on Pearl Harbor in December, 1941, the U.S. Maritime Commission urged the W.A. Bechtel Company of San Francisco to build a shipyard in San Francisco Bay. The site that was chosen was on the shore of Richardson Bay in Sausalito and was named the Marinship Shipyard. Recruiters searched for people from around the country willing to come serve the nation in its hour of need by constructing deseraely needed warships. The resulting influx of 75,000 Americans into southern Marin County had an impact on the area every bit as great as the 49er Gold Rush a century earlier. In all, 93 ships, including 78 tankers and 15 Liberty cargo ships were built over a 3½-year period. By the end of World War II the shipyard had only 600 employees left out of 20,000 at its peak. In 1946, Marinship was turned over to the U.S. Army Corps of Engineers. The Corps only needed a few of the shipyard buildings, including the warehouse that now houses the Bay Model. The remainder were eventually developed for commercial and public use.
As the group entered the Visitor Center, Bob led them past the Marinship Museum, which relates the history of the shipyard, and noted that the Center also hosts a variety of educational workshops covering Bay ecology, environmental issues, and the history and culture of San Francisco Bay. As evryone entered the large open warehouse area housing the model, Bob assembled the group near its center and briefly described the Bay Model. It was built in the mid 1950’s to simulate the effects of several bold ideas put forth during the early days of the Cold War to dramatically transform San Francisco Bay. Similar scale models were constructed by the Army Corps of Engineers to model Chesapeake Bay and the Mississippi Delta.
The main driving force behind the Bay Model was the Reber Plan. This and other plans evolved because of concern over sufficient fresh water and increasing traffic congestion as the Bay Area’s population continued to grow after the Second World War. The proponent of the Reber Plan (originally dubbed the San Francisco Bay Project) was John Reber, a former school teacher and theatrical producer. His idea would have dammed the Bay at two points, between Richmond and the Marin Peninsula, and between Oakland and San Francisco. Two freshwater lakes would have been formed in what is now San Pablo Bay and in the South Bay. The plan also called for a torpedo boat base at the Marinship site, a submarine base north of Tiburon near San Rafael, adding 20,000 acres of landfill to the East Bay and enlarging the deepwater harbor by 50 miles, and providing high-speed highways and railways linking portions of the Bay over the dams. [Read more about the Reber Plan at the Bay Model Association’s website.]
Critics pointed out the destruction of commercial fisheries, increased sewage disposal problems, potential flooding, and undesirable effects on the ports of Oakland, Stockton, and Sacramento. Although the State of California, the Bureau of Reclamation, and the Army Corps of Engineers opposed the plan, it was proposed that a scale model of the Bay be designed and used to test the effects of the Reber Plan. The model was finished in 1957. Subsequent tests showed that Reber’s plan would not conserve 2.4 million acre feet of fresh water as claimed, and that it would otherwise have had disastrous effects, including 15 foot tides! The Reber Plan was not the first, nor the last, plan calling for major damming and landfill in San Francisco Bay. The 1929 Walker Plan proposed a dam across the Golden Gate to transform the Bay into a large freshwater lake. The Cal-Water Project of 1952 proposed a barrier between Point Richmond and California Point that would create a huge freshwater lake in San Pablo Bay, and include an 8-lane freeway with 2 railways across its top. Other proposals for major alterations to the Bay include the Swanson Plan (1959), which would have created a dam across the Carquinez Straits and filled in the Bay with rock from San Bruno Mountain and other sites around the Bay Area; and the Savage and Weber Plans of 1962.
Looking across the model out the Golden Gate, with Angel Island in the foreground.
As the group toured the model, members were impressed with the size and detail of the 1.5 acre structure. The model is constructed of 286 carefully sculpted 12-by-12 foot concrete slabs covering San Francisco, San Pablo, and Suisun Bays, and the Sacramento-San Joaquin Delta from Verona on the north to Vernalis on the south. The bulk of the Bay was completed in 1957, and the Delta section was added ten years later. It has a horizontal scale of 1 foot = 1000 feet and a vertical scale of 1 foot = 100 feet, for a vertical exaggeration of 10:1. The 4 to 4½-foot tidal action of the Bay is simulated by computer-controlled pumps that operate at 100 times the natural diurnal cycle. This feature allowed the engineers to acquire accurate data over a much shorter time frame than if the model actually functioned in accordance with the natural tidal cycle. In this scaled up mode, 30 days worth of data can be simulated in just 7.2 hours.
View of the model Bay Bridge and Yerba Buena and Treasure Islands. NAS Alameda (former) is to the left and the Berkeley Marina is in the foreground. Each of the dark “whiskers” in the bay was designed to mechanically retard the flow of the water in order to mimic recorded tidal flow patterns and speeds. A full ebb and flood tide can be simulated in a matter of minutes.
The model can accurately reproduce Bay flow regimes, but allowance must be made for the additional frictional resistance caused by the vertical exaggeration The designers cleverly embedded adjustable copper metal strips in the concrete bottom to better simulate tidal action and water salinities. Bob demonstrated the dynamic action of the model using a squirt bottle of purple dye to color the water and show the flow direction at a given location. The model has been used to track the dispersion of oil spills in the Bay, but Bob noted that it cannot take into account the effects of wind. Where graduate students once kept vigil recording data for engineers to process by slide rule, now a computer carefully controls the pumps that regulate the model’s water level to accurately simulate the ebb and flow of the tides.
Further discussions inside the Bay Model.
After several decades of modeling a variety of engineering projects, the Bay Model has been replaced by computer programs that simulate its hydrodynamics. Now it is no longer used for research, but as an instructional tool to show the public what innovation and sound engineering principles can create. The Bay Model is a wonderful instructional tool and an inspiration to a future generation of scientists. It is a focal point of military and maritime history, culture, technology, and ecology. Open to the public Tuesday through Saturday, admission is free. For more information, call the Bay Model in Sausalito at 415-332-3871 or visit their website at http://www.baymodel.org.
Ranger Robert Stevenson, standing on Alameda, leads a discussion (Oakland Estuary in the foreground and Bay Farm Island behind him).
The NCGS sincerely thanks ranger Bob Stevenson for an excellent tour and lecture on the Army Corps of Engineers Bay Model. He entertained and educated the NCGS audience on this fascinating facet of San Francisco Bay Area history. Our many thanks to NCGS Field Trip Coordinator Jean Moran and her husband Bill Martin for arranging this personal tour for our members, and for providing the refreshments afterwards. This was an afternoon well spent at the dock on Richardson Bay where a former military shipyard is quietly remembered in a unique museum display.