Oakland Int'l Contends with Wetlands, Endangered Species & Seismic Risk at New Fuel Farm

Author: 
Ronnie Garrett
Published in: 
November-December
2009




"Building a fuel tank farm isn't sexy; it just needs to be done," says Tom McCartin, chairman of Oakland Fuel Facilities Corporation (OFFC) at California's Oakland International Airport. With 15 carriers uploading an estimated 117 million gallons of jet fuel in 2009, it was simply time to replace the aging fuel farms, McCartin explains.

Although the $25 million project may not have the makings of a Hollywood blockbuster, it has multiple subplots and plenty of drama - by airport infrastructure standards. "You had seismic issues, you had proximity to the bay and you had proximity to the wetlands where some endangered species might reside," McCartin details. "We had to be very careful."





Facts & Figures

Project: Fuel Storage Facility (Tank Farm C)

Location: Oakland (CA) International Airport

Cost: $25 million

Design Engineer: Argus Consulting

Design-Build Contractor: Malcolm Drilling Company

Geotechnical Engineer: ENGEO

Impetus: Replace aging fuel farms with facility designed to withstand local seismic load

Extra Challenge: Protect wetlands and endangered species on construction site

Status: Soil stabilization, deep soil mixing and fuel tanks complete; construction of facility ready to begin

Movers & Shakers

Apprehension about seismic risk prompted the consortium and Port of Oakland, which owns the property and holds the lease, to move the replacement project to the front burner. "The airport and the airlines had a sense of urgency on trying to move forward with a new facility," says Brandon Mark, aviation senior supervisor properties representative with the Port of Oakland.

The airport's existing fuel farms are located just six miles from the Hayward Fault Zone, Mark explains. Because they were designed back in the 1960s, they don't meet today's construction standards for facilities located near earthquake faults. Geotechnical, environmental and geologic assessments by ENGEO detailed specific concerns. "This fault zone is capable of a very large earthquake, which meant our site had relatively high seismic exposure," says Bill Rudolph, principal consultant with ENGEO. "In addition, the soft soils of a marine environment are particularly susceptible to seismic-related problems and failures, and our site is actually on land that was reclaimed from the San Francisco Bay." According to ENGEO studies, the site rests on 10 feet of Bay mud.

The true test was designing a facility able to withstand local seismic loads - something the former facility located on the site, Tank Farm C, had not been able to do. When the Loma Prieta earthquake shook the San Francisco Bay region in October 1989, one of the tanks shifted and tilted. Although it did not rupture, the airport had to empty the tanks immediately and stop using the farm, says Terry Harvey, project manager for design-build contractor Malcolm Drilling Company.

Mixing It Up

The site's history presented tenable bearing failure concerns for any new facility erected atop the grey field area. Sizable site improvements were needed to construct a fuel farm on the damaged site, says Jon Currier, vice president of engineering firm Argus Consulting.

The project's design team eventually decided on $3 million of site improvements recommended by ENGEO. Malcolm Drilling used a technique called deep soil mixing (DSM), a method that originated in Japan, where seismic loads rival those in California. Malcolm Drilling's DSM system uses mechanical mixing tools to combine the soil with cementitious slurry pumped at low pressure. The method allows the creation of large soil mix columns, typically 5 to 8 feet in diameter, at depths up to 80 feet.

The company used DSM to:

- install a soft cement shoring wall around the entire site with a bioswale to protect neighboring wetlands.

- create a dike wall support system to catch spilled oil if a tank fails or leaks and to work with the retaining wall to prevent lateral spreading during an earthquake.

- construct tank foundations supported by 7-foot-diameter soil cement columns.

- add pump pads, pipe supports and filter pads around the tanks.





Wetlands border Oakland International's fuel farm site on three sides and a large pipeline transportation/energy storage company operates on the fourth side. In addition, the site sits on an area that was once part of San Francisco Bay, visible in the upper left.

Why DSM?

According to project consultants, DSM's primary advantages include settlement control and increased bearing capacity in soft soils. Its ability to create large diameter soil mix columns also makes it suitable for mitigating the effects of liquefaction-induced settlements and lateral spreading, which can occur during an earthquake. "This technique stabilizes the site under earthquake loading as well as static loading," explains Michele Shriro, ENGEO senior engineer/project manager. "With this site, there were concerns for vertical settlements under normal conditions as well as lateral deformations during earthquake loading."

With DSM, the mixer first fluidizes the soil, making it the consistency of soft ice cream, and then injects a binder into the soil matrix. The binder decreases the soil's permeability and increases its unconfined compressor strength. "In essence, you take soil that's very, very weak - stuff that may not even support your own weight - and mix it with cement to make a moderate, loose-strength concrete," Rudolph explains. "This allows the structures you're building to be built on normal shallow foundations."

DSM also satisfied the noise concerns of airport neighbors and the airport itself. A California Environmental Quality Act review limited construction to the hours of 7 a.m. to 5 p.m., Monday through Friday. DSM kept noise levels at bay during operation, because it is quieter than traditional construction methods, which drive I-beams into the soil. By contrast, DSM's stabilization work is performed underground.





Goats were used to clear pampas grass from the construction site without risking harm to indigenous wildlife.

Green Hoops

Environmental concerns of a different nature were posed by wetlands that border the site on three sides and are regulated by the U.S. Army Corps of Engineers.

"It took a long time to wade through the potential environmental issues," acknowledges Mark.

Removing the pampas grass that had overtaken the site during its 20-year hiatus became a project-delaying issue. Per state environmental consultants, the process used to clear the tough, stringy grass couldn't harm indigenous species possibly living in the marsh, such as the critically endangered salt marsh harvest mouse. "We considered having workers go out and clear the pampas grass with machetes," recalls Currier. "But that would have taken months and cost hundreds of thousands of dollars."




A liner along the perimeter of the wetlands prevented spoils generated during the deep soil mixing process from spilling into the wetlands.

On Harvey's recommendation, the airport contracted a herd of 120 goats to eat the grass for about $16,000. The goats cleared the area without posing risks associated with mechanized equipment. "We'd still be figuring out how to clear the site if it hadn't been for them," Currier quips.

The next concern was keeping the spoils of the DSM process out of the wetlands. "Soil mixing is a very, very, very messy process," notes Harvey. The site where Malcolm Drilling planned to create 10,000 cubic yards of soil and soft cement sat 5 feet above grade, with grade being wetlands.

To prevent spills, Malcolm Drilling erected barriers around the perimeter and created a small working space. A liner along the perimeter served as a moat, containing the spoils from the wetland so they could later be transported to the Port of Oakland's materials site. Waste generated during the DSM process makes excellent backfill for construction projects, Harvey explains.

Satisfying the project's environmental constraints, he says, was a resounding success thanks to the right attitude and lots of up-front legwork. "We spent quite a bit of money at the start of the job to ensure we didn't disturb the wetlands," he says. "As a result, there was not a bug harmed, and all construction waste was recycled."

Target: 2010

With structural and environmental issues behind them, site improvements are complete and three 35,000-gallon fuel tanks are being readied for operation by February 2010. Construction of the operating facilities is next.

The entire project remains on a three-year schedule set by OFCC. "It was a very tight timeline to get something like this going," acknowledges Shriro. "Everyone really collaborated and came up with their most creative solutions - and it really, really worked."

According to Rudolph, the project proves what can be accomplished if everyone works together to push a project forward. "Complicated projects with multiple stakeholders can get accomplished in a very rapid timeframe provided you create a collaborative atmosphere based on trust," he insists.

According to McCartin, the cooperative effort helped meet the Port of Oakland's primary goal: constructing a state-of-the-art facility at a reasonable cost. Because Oakland International competes with two neighboring airports for business, completing the project without breaking the bank was critical, he notes.

"It's a replacement project," says Mark, "but it is state-of-the-art and cleaner and safer for everybody."

Subcategory: 
Fuel Operations

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