Giant bridges are always engineering marvels. The new Gerald Desmond Bridge will also be a wonder, with towers rising more than 500 feet into the air and a roadway standing 205 feet over the water.
Building the new bridge begins with a unique engineering challenge – not up high but down deep in the earth.
“We’re building this bridge to last 100 years,” said Al Moro, Acting Executive Director of the Port of Long Beach. “Replacing its outdated predecessor starts from below the ground up.”
Shoring up the soil beneath the new bridge’s footprint is both a crucial first step and a massive undertaking. The modern 1.5-mile-long structure will traverse the center of the nation’s third-largest oil field, where more than 6,000 wells have been drilled since oil was discovered in 1932. Roughly 13 miles long and 3 miles wide, the Wilmington Oil Field encompasses nearly all of the Port and stretches into portions of the city of Long Beach and the ocean. About 600 wells remain active today.
Twenty-three active and idle wells sit in the path of the new bridge. To secure the site, the active wells require relocation and the idle ones must be abandoned. Getting the job done involves digging down deep enough – more than 200 feet – to extract huge metal pipes known as casings and filling the cavities with a precise mix of materials to re-establish the natural consistency, density and strength of the soil. The work is anything but routine and the scale is immense.
Separately, the Port must clear another 18 wells that had been previously abandoned. Removing them and stabilizing the land requires significantly greater care and horsepower due to utility lines buried within the old fill; casings damaged by explosive charges once used to seal inactive wells; surrounding concrete pads; and double steel casings.
To meet the challenge, engineers and crews devised a unique method of extracting the remnants in stages to protect the integrity of the shaft and the environment. The technique involves encasing each old casing in a larger-diameter pipe and removing debris in 10- to 30-feet-long vertical segments. To clear one site, a skilled dive team was lowered into a casing to perform the work.
Another factor is the property’s history of “subsidence.” Years of pumping oil up caused the ground to sink during the 1940s and 1950s. The city’s oil field operator stabilized the land and restored it to its original heights in the 1960s, but that history is another reason to proceed with caution.
“We’re taking extraordinary measures to ensure the stability of the land and prevent contamination of the underground layers of soil and the water table,” Moro said.
Oil wells aren’t the only underground obstacles that must be removed. Readying the site also involves relocating 10 miles of horizontal utility lines – water, natural gas, sewer, storm drains and electrical wiring – that form a web of hidden infrastructure supporting the present-day power and drainage needs of the Port and the city. At times, the work involves injecting liquid nitrogen into the soil to freeze the land to prevent water from seeping into the trenches dug to uncover the lines.
Lastly, clearing the path for the bridge involves demolishing 18 buildings, including a former fire station and the Port’s Maintenance Yard.
The added complexity has increased the cost of replacing a vital link in the nation’s infrastructure for cargo and commuters. All told, the budget now stands at $1.263 billion, which is being paid for by a combination of Port revenues and federal, state and regional transportation funds. The total includes almost $240 million for the oil field work and nearly $92 million for contingencies and potential risks, should they arise.
The path for the new bridge is expected to be cleared by year’s end. Then, work on the foundation for the new bridge will begin with the drilling of approximately 330 piles deep into the ground. The equivalent of 18-story subterranean pillars, the piles will support about 70 columns and the two distinctive 515-foot-tall towers that will be the centerpiece of the cable-stayed section of the new structure.
“The new bridge will be an icon,” Moro said. “It also will symbolize the Port’s commitment to a future built on best practices and the highest standards.”