MOSS LANDING, California—MBARI has completed the construction of its new test tank and the expansion of its existing Building B. The 10-meter-deep (35 feet) tank is used for testing equipment, sensors, and underwater vehicles. The new building also provides 24,000 square feet of office and lab space.

MBARI continues to be on the cutting edge of technology with this construction project. Our structural and geotechnical engineers used several new construction technologies to implement the architectural design. Many of the products used to furnish the building were selected because they are "green" or have minimal impact on natural resources.

The original Building B, built in 1989, was constructed as a slab on grade and designed to "float" on the surface in the occurrence of an earthquake. The expansion, primarily because of the test tank being eight meters below grade, needed to be firmly anchored in the subsurface via soil-cement columns. These different design criteria dictated the first step of construction, which was to improve the performance of the existing building to match the new design. This requirement was met by a process called injection grouting. Holes were bored through the building foundation to a depth of 48 feet. Cementitious grout was then injected at two-foot intervals at a pressure of 800 pounds per square inch to within eight feet of the surface. The holes in the existing foundation were capped with cement when the injection was completed. Two hundred fifty eight injection sites were installed to stabilize the building.

Building of the expansion began with the demolition of an existing structure on the site on February 14, 2000. The cleared site was improved using a new technique that created subterranean soil-cement columns around the test tank and in strategic building support locations. Using a special augur-injection bit that drilled holes to a depth of 52 feet and simultaneously injected cement slurry that mixed with the existing soil (mostly sand). This process created concrete columns without first excavating a hole and forming up a piling. Steel I-beams were inserted into each supporting column point and in half of the columns around the perimeter of the new test tank. The soil-cement columns around the test tank also provided a cofferdam that halted salt water intrusion allowing construction to proceed. The water table at MBARI is located only four feet below grade. Additional injection grout points were installed to provide support under the expansion site.

Following the installation of the soil-cement columns, the new test tank was excavated. The walls of the test tank were poured in stages, utilizing aluminum form structures and plywood. In an effort to conserve resources, the forms were re-used for concrete pours throughout the project. The test tank holds 375,000 gallons of water. The tank is 30 feet wide, 45 feet across, and 35 feet deep, and is illuminated internally by remote source fiber-optic light pipes. MBARI engineers and scientists have already begun to use the tank to test equipment and underwater vehicles.

The Building B expansion also includes offices, laboratories and staging areas providing the necessary space for MBARI to carry out its mission.

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