The Methane Down Below

One witness thought it was “raining fire.” The earth was belching flames through cracks in the pavement, tongues of fire marching in a steady progression across a shopping center parking lot on 3rd Street near Fairfax Avenue in West Los Angeles.

The methane gas explosion that ripped through a Ross Dress for Less store in March 1985 left 24 people injured and forced the closure of stores in the center for several days.

Nature had sent Los Angeles yet another potentially lethal message: Without adequate venting, methane trapped below pavement can build to explosive levels with disastrous results.

Echoes of that explosion have been very much on the mind of Angelenos as the Los Angeles Unified School District board wrestles with ways to solve the problem of methane seeping through the earth at its half-completed Belmont Learning Complex site just west of downtown.

If the methane problem at Belmont cannot be solved, the school district may be forced to abandon the $200-million education and retail project.

Safety Questions

The controversy swirling around Belmont has raised questions regarding the safety of residential and commercial developments in other parts of Southern California.

The region is dotted with working and abandoned oil wells from Santa Clarita in the north to Newport Beach in the south. And where there are oil wells, there is methane.

Does that mean neighborhoods and commercial developments built on old oil fields face the same risks that have caused so much concern at Belmont?

There is certainly risk whenever explosive gases are present, experts say, but building codes and state agencies have been able to keep that risk at manageable levels for the most part.

When builders follow proper procedures to vent methane, the risk of accidental explosions is virtually eliminated, experts say.

Having pumping oil wells on a site is better than having improperly abandoned wells because working wells vent methane harmlessly into the air, said Richard Baker, district deputy of the state Division of Oil, Gas and Geothermal Resources.

Huntington Beach-based petroleum drilling consultant Dick Chalk stressed that “the potential risk of methane problems is probably very small, but it’s always a possibility. It’s that 1% chance that worries you. The gas will seep up through cement, and eventually come to the surface. It’s just good oil field practice to go ahead and vent something. Otherwise, an explosion can happen.”

Colorless, Odorless --and Explosive

Methane is a colorless, odorless, highly explosive byproduct of the oil fields on top of which much of the metropolitan region is built. The 70-odd fields in the region are primarily clustered along the area’s major earthquake fault lines, where oil seeps out of the ruptured rock.

Over several decades, as Los Angeles and its environs have shifted from an oilman’s town to a developer’s dream, three-quarters of the area’s 33,000 oil wells have been abandoned.

“The only open space left to build on in L.A. is the open oil fields, so people are building there,” said Baker, who oversees review of all construction permits for Los Angeles and Orange counties to make sure old wells are properly capped and vented.

“Land values are so high, by building houses you can now make more money than pumping oil, so there’s a big urbanization pressure,” he said.

And that means underground pressure in oil fields begins to build back up.

Once a well is abandoned or sitting idle, “what Mother Nature did to create the oil field, Mother Nature is going to continue to do--fill that oil field back up,” Baker said.

That repressurizing may cause oil to seep, and with the seeping oil come swelling methane fumes. If those fumes find a weak link in an old well, where they can mix with air, they can and do explode, ignited by as little as a light switch being flicked on. Methane in concentrations as low as 5% can be explosive.

“If you have oxygen and gas and a spark, you get an explosion,” Baker said.

It is impossible to know how fast an area of an oil field will repressurize, but there are telling examples.

In 1973, a retired sea captain’s Newport Beach cottage began filling up rapidly with crude oil. The culprit was an abandoned oil well directly below. The force of oil rising from the improperly sealed well cracked the concrete foundation and flooded the kitchen.

“Mostly the old wells just belch out oil and gas,” Baker said.

The captain’s house was partially torn down to get to the leaking well, which was then properly capped.

Several years later, a real estate agent preparing to show a house in Newport Beach turned on a light switch, and the house burst into flames and was gutted. No one was killed. The fire was attributed to trapped methane from an old well.

Four years after the Ross Dress for Less explosion in the Fairfax district--just blocks from the sprawling Park Labrea apartments--methane appeared in nearly explosive concentrations in the basement of a Kmart store in the same area.

The 1985 shopping center explosion led to quick passage of state legislation that set aside funding for testing and remediation. Numerous old wells have been properly shut down as a result, but others, especially wells from the last century that were abandoned before the state oil and gas division was established, are uncharted territory.

After the Ross explosion, wells were sunk near the shopping center to relieve pressure and gas detectors were installed, said Dana Prevost, an engineering geologist in the city Department of Building and Safety.

Los Angeles also revised its building code, in some cases requiring vents and nonporous membranes beneath a building’s slab to direct methane to vents, he said.

John Sepich, a methane specialist who runs Sepich Associates in Moorpark, said that even high concentrations of methane in the soil are not a problem if construction firms follow the Los Angeles Building Code, which he said embodies an “extremely conservative” approach to the explosive gas.

The code calls for laying down perforated pipes to collect and vent the gas, and then covering the pipes with a plastic membrane.

The membrane, he said, is essentially stretched “like a drumhead” between foundation footings. Then the foundation slab is poured on top.

The code calls for methane detectors or fans to be installed in the building aboveground, he said.

Sepich said he recommends installing the membrane underneath foundations where methane is found in excess of 1.25% of air by volume.

Just such a membrane is being placed on a building under construction less than three blocks from the Belmont site because an area along one side of the foundation was found to be contaminated with methane.

Barriers for Buildings

Sepich’s firm was hired to design a methane protection system at Belmont. His design, which was being implemented before work on the system was suspended, included a barrier under buildings and passive collection through perforated plastic pipes.

He has designed barriers for other buildings, including the Los Angeles Central Library. He said his firm designed the methane barrier for the library after testing found areas where the methane concentrations were much greater than at Belmont. And he said they were discovered in much the same way--after construction had started and the environmental testing firm detected methane in sample borings.

“My feeling is that the gas situation at the library is much more severe than it is at Belmont school,” he said.

The library job, however, was more involved because it required building a membrane under a basement reaching 60 feet into the ground. In addition to the barrier, he said, the library has methane gas detectors inside.

For all the risks that building on old oil fields poses, “accidents are few and far between,” Baker said. “Cities and developers want to have safe projects.”

In the Los Angeles Basin, all cities where oil operations are underway send developers to the state Division of Oil and Gas to have their projects reviewed, Baker said.

Although those referrals are voluntary and advisory, Baker said, “I think it has worked pretty well.”

David Keim, the principal inspector at the Los Angeles Department of Building and Safety, said his office refers all permit applicants to the oil and gas division if they want to build on old oil fields.

“We require clearance from oil and gas before we issue a permit,” he said.

But some governmental agencies do not need such a clearance to build. School districts get their clearances from the office of the state architect. The Division of Oil and Gas may review the project, but it has no power to block it.

In Belmont’s case, Los Angeles school officials’ long frustration over being unable to build a new high school near downtown led them to cut many corners in their environmental reviews of the project.

First, to purchase the land quickly in 1994, they declared that there would be no negative environmental impacts. At the time, however, a widely distributed memo outlined deficiencies in the assessment of the hazards of methane and other oil field chemicals. But those concerns were not addressed in the district’s later environmental impact report.

The omission kept the state Department of Toxic Substances Control out of the review process when the district presented its Belmont plans to the state architect.

Baker said he and his staff repeatedly told L.A. Unified about the oil wells on the Belmont school site, “as far back as 1989.”

Since cities and counties require private developers to get approvals for their projects from the state oil and gas office, the agency now reviews 1,200 applications for building permits a year--a sharp increase from the 40 or 50 it reviewed just 15 years ago.

Each developer must obtain oil maps from the state office, then excavate the site to determine if wells are on the property and where they are.

“The first thing we always tell them is it’s better not to build over a well,” Baker said. “We recommend they don’t.”

There may be a well on the property, Baker said, but his office tells developers to design their projects so that no structure is directly over the well.

If it is necessary to put a building over the well, Baker said, the developer should ensure that the well is brought up to current standards with plugs and venting.

Any leaking well on the site, even if it is not near the planned building, must be reported immediately, and all wells under houses or businesses must be vented.

Tests for leaks and on-site inspections of capping and venting are done by state engineers before certification is issued.

Among the newer housing developments atop old oil fields, upscale Huntington Place in Huntington Beach offers a good example of yet another reality of modern-day Southern California living.

On the sidewalks in front of the million-dollar homes in the gated community are tall, spindly concrete structures that look like lampposts without the lamp on top.

They are methane vents.

“Yeah, we signed a disclosure report saying we’d been told that was to vent the gas,” said Cindy Lang, who moved in with her family two months ago. “My husband and I really weren’t concerned about it. I’ve never noticed any smell or anything. You could just worry yourself away about every little thing--earthquakes, floods, oil--or you can just live in the house you want and not worry.”

Times staff writers Ralph Frammolino, Neda Raouf and Doug Smith contributed to this report.

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Oil and Trouble

Oil drilling is a century-old fact of Southern California life. Edward Doheny discovered oil in 1892 west of downtown Los Angeles, just blocks from the Belmont Learning Complex site. Pools of black gold may harbor the risk of potentially explosive methane that can seep to the surface, making measures to control it important in construction codes.

Types of Methane

* Shallow biogenic methane is created as bacteria in the soil decomposes oil discarded during drilling, leaving methane as a byproduct.

* Petrogenic methane is formed along with other gases deep within the oil field, and rises to the surface through rock layers or old oil well shafts.

Geology

The ground beneath Los Angeles is made up mostly of sedimentary layers that were laid down millions of years ago before the inland seas that once covered the L.A. Basin receded. Over time, a combination of pressure, tectonic activity and erosion brought oil-bearing layers close to the surface.

Danger

Methane presents a risk of explosion when it accumulates in an enclosed structure. Mixtures of methane and air with the methane content between 5% and 15% by volume are explosive.

Remedies

1. Capping and venting abandoned wells.

2. Laying down perforated pipes to collect and vent methane, and then covering the pipes with a plastic-type membrane that directs the gas into them. A building’s foundation slab is then poured over the membrane.

3. Installing methane detectors or fans in a building above ground.

Source: California Conservation Dept., Division of Oil, Gas and Geothermal Resources; Los Angeles Times archives