A new warning about the heightened risk of liquefaction in Alameda during the next big earthquake should catch the attention of leaders at the U.S. Department of Veterans Affairs (VA). They plan on building a clinic and veteran benefits facility on an artificially constructed hill out on the old airfield in the middle of an earthquake liquefaction zone.
In an April 17 Mercury News story, U.S. Geological Survey (USGS) Earthquake Science Center director Christine Goulet singled out the City of Alameda for being at particular risk of major damage from an earthquake along the Hayward Fault. The ominous headline was, “A ‘house of cards’: When the Big One comes, will Alameda be ready?”
A follow-up story published in the UK’s Daily Mail on April 22 stated, “In addition to the heightened risk of liquefaction in Alameda, (the USGS) says there is also a 70 percent chance that one or more quakes of a magnitude of 6.7 or larger will occur before the year 2030—bad news for residents of the island community, which is almost entirely set on reclaimed land.”
Earthquakes have occurred on the Hayward Fault about every 150 years. The last one was in 1868 when Alameda was mostly an oak forest and marshland. So, we are overdue.
The earthquake risk for the proposed VA clinic comes from the fact that the ground consists of sand and silt, the type of soil susceptible to liquefaction. The risk will be compounded by the fact that the VA will be bringing in 10,000 truckloads of soil to raise the elevation of the site for sea level rise protection.
Piling more fill on top of existing fill and then building something on top of it, as proposed by the VA for its clinic, is exactly what engineers warned about in the 1996 Community Reuse Plan for the Navy base. The section on Seismic, Geologic, and Soils Hazards Policies states, “Expected strong to violent ground shaking could result in seismically-induced ground failure in portions of NAS (Naval Air Station) Alameda. The majority of the site is underlain by hydraulically-placed (pumped from a barge in the Bay) sandy fill that could be subject to liquefaction.” The term refers to loose sandy soil acting like a liquid due to severe shaking, which can lead to structural failure.
The engineers go on to say that using fill material on top of fill should be limited. “The placement of artificial fill should be limited to reduce the potential for increased loading and associated settlement in these areas of NAS. Reconditioning (compaction) of existing subgrade materials would be preferable to placement of fill.” But in the case of the proposed location of the VA clinic, simple compaction is not an option because the site has to be elevated with more soil to avoid the risk of sea level rise.
During the VA’s environmental assessment completed more than a decade ago, the engineers who wrote the geotechnical assessment only looked at liquefaction potential from the San Andreas Fault 12 miles from the site, not the Hayward Fault six miles away. The Hayward Fault is the real sleeper, according to Goulet.
The VA does not plan on driving steel pilings down to solid ground to reduce risk of earthquake damage. It’s too far down. Instead, they propose to build the VA clinic on a giant concrete slab with concrete piles that will supposedly remain intact and level during a major earthquake. Essentially it will be a concrete slab on top of a sandwich of two layers of fill.
Why is the VA pursuing this challenging engineering exercise to withstand both sea level rise and earthquakes when better alternatives exist at Alameda Point? It complies with a national policy called “One VA,” which seeks to consolidate services at one site wherever possible because it is more cost efficient to have one piece of land rather than two or three. While the columbarium-style cemetery is slated for the area out on the runways, the VA may want to consider whether building its clinic at the same location is prudent.
There are much more desirable sites for the clinic at Alameda Point that could be made available for the cost of new infrastructure. Two sites immediately come to mind.
One site is the location near the USS Hornet Museum where the city had previously offered 45 acres for free to the Berkeley Lab for its second campus in 2011. The VA clinic and parking lot would require only about 30 acres of that land. Long-range sea level rise projections have this area remaining unflooded into the distant future, thus the questionable practice of stacking landfill to avoid flooding of a structure could be avoided.
Another ideal site would be the location of the Bachelor Enlisted Quarters (BEQ), which sits on a block of land approximately 30 acres in size. This complex could be demolished. Locating the VA clinic and benefits facility here would place it a short distance from the proposed veterans cemetery. It would eliminate all the truckloads of soil required to elevate the proposed VA site because the BEQ site will be protected by a levee someday.
Knowing the latest earthquake predictions and options to reduce risk, it is not too late for the VA and the city to revisit building the clinic at another location. It would be less risky and probably less costly for the VA. It would be easier for veterans to access via public transit. And it would be better for the city, with new infrastructure and a new facility for veterans seamlessly integrated into the community, not stuck out on the old runways.
Contributing writer Richard Bangert posts stories and photos about environmental issues on his blog Alameda Point Environmental Report, https://alamedapointenviro.com/. His writing is collected at AlamedaPost.com/Richard-Bangert.
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