Chevron Plant in El Segundo Lays Plans for Massive Oil-Leak Cleanup

These days, around the offices of Chevron’s oil refinery in El Segundo, Pat Hughes is known as “Mr. Wizard� after the children’s TV science show host of the 1950s and ‘60s.

Called upon to explain to company engineers and visitors how Chevron will retrieve 252 million gallons of oil and petroleum products that have spilled into the ground under the refinery, the 40-year-old hydrogeologist pulls out a stale cheese sandwich from a plastic sandwich bag.

Hughes, a Chevron employee for eight years, uses it to explain the layered geology beneath the 1,000-acre refinery and how Chevron plans to clean up the crude oil, gasoline and jet fuel that has leaked or spilled, contaminating ground water.

Hughes is one of seven people in the company’s Environmental Technical Support Group, a unit Chevron formed to handle a massive $86-million cleanup at the 77-year-old refinery.

Drinking Water Unaffected

State and local officials say drinking water is not threatened by the massive spills. The nearest drinking water wells are in Hawthorne, a couple of miles from the refinery. The bulk of the spill is under the refinery, although some has seeped a block or two beyond its boundaries in El Segundo and Manhattan Beach, state and local officials say.

The refinery, which processes up to 300,000 barrels of crude oil daily, sits on sand dunes. Oil pumps once dotted the area, and a lone pump still draws oil from about 2,000 feet below the surface.

Below the dunes are three aquifers separated by 20- to 30-foot-deep clay layers. Think of it as a triple-decker cheese sandwich, Hughes says, with the cheese as the clay.

The aquifer closest to the surface, on which pools of oil up to 12 feet thick float, is the Old Dune Sand Aquifer. This water is not used for drinking water. In the aquifer below it, called the Gage, small traces of oil equivalent to one pint of petroleum for every 80,000 gallons of water have been detected, Hughes said. Limited testing has not uncovered any hydrocarbon contamination in the deepest aquifer, the Silverado, he said. Only water from the Silverado is drawn for drinking in the nearby Hawthorne wells.

During the next two decades, Chevron, assisted by hundreds of subcontractors, will work to recover the lost petroleum products from underneath the refinery and clean up the water. Despite their efforts, Chevron officials concede, perhaps only 50% to 70% of the hydrocarbons will be recovered from the ground.

The biggest challenge facing Chevron, state and county officials say, is removing the oil without allowing it to spread further into El Segundo or neighboring Manhattan Beach, or to interfere with county wells built to halt the flow of saltwater from the ocean to the underground water supply.

Chevron will rely on a sophisticated computer model that tells what is going on under the refinery as the hydrocarbons are collected by pumping thousands of gallons of water in and out of the ground.

Cleanup Ordered

Last month, Chevron was ordered by the Los Angeles Regional Water Quality Control Board to begin the cleanup.

Before the cleanup order was issued, Chevron says it spent $36 million to devise plans for the cleanup and installed 80 wells to recover fuel vapors from under the ground and burn them in three incinerators at the refinery. The company plans to construct 10 more vapor recovery wells in El Segundo.

At the same time, company spokesman Rod Spackman said, Chevron is proceeding with an $80-million program to upgrade the refinery’s major tanks.

By the end of the year, he said, about 250 of the huge above-ground tanks will have a layer of polyethelene welded on top of their floors. A metal floor will be built above the polyethelene with a grooved, concrete slab built between the two. If a leak develops in the uppermost floor, the product is expected to run down the sloping concrete to the outside of tank, where it can be seen.

At the same time, Spackman said, the company is spending an additional $20 million to uncover buried pipes so leaks can be spotted faster. Pipes that must remain underground, such as those under roadways, are being put in casings so that if one springs a leak, it is possible to repair it before oil runs into the soil.

Beginning in the early 1900s, saltwater began to seep into the ground along the coastline, including the area below the refinery. This prompted the abandoning of drinking water wells, according to Jim Rancilio, an engineer with the Los Angeles County Flood Control District. To halt the flow of saltwater eastward, 144 wells were constructed over the years to inject fresh water underground and westward. Eight of the wells, which extend south from Imperial Highway to the Palos Verdes Peninsula, are on Chevron land near Sepulveda Boulevard, he said.

State and local officials said that as Chevron pumps up the spill beneath the refinery, it is possible that the barrier to the saltwater could be affected if water levels or pressures within the aquifers are altered.

Additionally, the hydrocarbons could be driven into El Segundo and Manhattan Beach. Chevron estimates that less than 1% of the total spill is under the El Porto area in Manhattan Beach, and less than 2% of the total has seeped into El Segundo.

To keep tabs on the saltwater barrier and the location of the oil, Chevron engineers spent two years gathering data on the geology under the refinery and feeding that information into computers. A three-dimensional computer model was developed that gave engineers a picture of the refinery’s ground water flow system. The model pinpoints 4,500 different water levels throughout the water basin under the refinery.

“We can ask the computer what is going on in each aquifer and it will spit out a series of lines telling us what the water is doing,� Hughes said.

‘50% of Answers’

Hughes and other engineers say they will not rely solely on the model to determine what is going on underground.

David Huntley, a hydrogeologist who teaches at San Diego State University and who helped devise the computer model, says it is “within 50% of the real answers.� Hence, 300 monitoring wells will be built and scattered around the refinery’s grounds. The wells will collect water and oil samples and other data, which will go into the computer model.

Hughes said Chevron has been operating 17 so-called “skimmer� wells. The wells reach into the Old Dune Sand Aquifer and pump up petroleum from the spill within an area about 50 feet wide, he said.

However, those wells are expected to be converted to more efficient water recovery wells in the future, Hughes said. By late 1989, he said, the company hopes to have more than 50 such wells operating, pumping out 3,100 gallons of water every minute from the aquifer. The wells can retrieve hydrocarbons from about a 250-foot-wide area, he said.

Hughes said the wells, placed about 500 feet apart, will be equipped with two pumps--one to retrieve the water, the other for the oil. As the water is pumped out of the ground, a “cone of depression� is created on top of the aquifer. The oil on top of the water then gravitates toward the depression, where it is sucked up by a separate set of pipes. Once above ground, the oil is refined and the water is reinjected back into the ground through other wells.

2 Million Gallons Removed

Since the beginning of 1987, Hughes said, 2 million gallons of oil have been removed from beneath the refinery. At present, 25,000 to 30,000 gallons of oil are being collected each week, he said.

Chevron, under the water board order, must meet strict reporting requirements, keeping the agency informed about the cleanup’s progress and recovery of the petroleum and oil products. The company estimates that it could begin cleaning up the water in seven years.

But water board and company officials say it is unlikely that all of the spill will ever be recovered. As years go by and it becomes increasingly harder and costlier to clean up the oil, the project may be stopped.

“It is going to take a long time,� said Ray Delacourt, who is overseeing the cleanup project for the water board. “At some point in time we are going to get to a point where we say, ‘Shut the thing off.’ �