A new report on Playa Vista says the site of what would be Los Angeles‘ largest commercial and residential development sits on vast pockets of explosive methane gas and straddles a potentially active earthquake fault.

The study, conducted by Exploration Technologies Inc. (ETI) of Houston for the city of Los Angeles, found far more methane than was believed to lie beneath the 1,087-acre site near Playa del Rey. The 1993 Playa Vista Master Plan Environmental Impact Report, relied on by the city in approving Phase I of the project, dismissed the risks of methane leaking to the surface as “insignificant.”

The findings will force developer Playa Capital to undertake measures to keep explosive gas from becoming a safety hazard. Los Angeles building officials are also considering whether to demand new mitigation measures for the already approved 705-unit Fountain Park Apartments and the Visitor’s Center, where prospective residents will receive sales information.

The discovery of an earthquake fault that is potentially active — meaning that it has not produced a known quake — is especially troubling. Scientists from ETI say that “thermogenic” (originating deep within the Earth) methane gas already travels vertically up to the surface through cracks in the fault. An earthquake could move this fault, bringing “a rapid flux of very large volumes of thermogenic gas to the surface along the Lincoln Boulevard Fault plane.” ETI scientists say that the Playa Vista fault zones resemble those near Sylmar, where a magnitude-6.6 quake in 1971 sent tremors down to an old oil field in the Fairfax area, releasing oil and gas that created a fire and explosion hazard.

The new report will change the way the Los Angeles Department of Building and Safety handles Playa Vista permits.

“No new permits for grading and construction in Phase I will be issued until the developer submits additional reports on how they will mitigate the hazards Dr. Victor Jones of Exploration Technologies describes,” said Bob Steinbach, chief inspector. “And even then, it will be up to Dr. Jones to say if the mitigation measures are adequate for protecting what Playa Capital wants to build.” Officials from Building and Safety and the Los Angeles Department of Planning will then determine whether to grant new permits.

Playa Capital‘s vice president, David Herbst, said the project would not be slowed by the report. “Contrary to what you might want to believe, Playa Vista continues to move forward on schedule. We will determine — on a building-by-building basis — the most prudent mitigation plan.”

Playa Capital’s full plans for Playa Vista include 13,000 residences for 29,000 people, and 5 million square feet of office space employing 20,000 workers. For planning purposes, the 1,087 acres of Playa have been divided into two “phases.” Phase I, land mostly east of Lincoln Boulevard, has been zoned and subdivided for residential and commercial buildings and received city go-aheads except for final grading and construction permits. City officials have extended ETI‘s contract to conduct additional methane studies for Phase II.

So far, the largest methane seep found at Playa Vista covers a kidney-shaped area just east of Lincoln some 1,700 feet long and from 200 to 400 feet wide. A second, smaller seep is just to the east of the first. The third seep, on the far eastern border of the property (the old Hughes aircraft plant site), is 600 by 800 feet; it lies on top of the Charnock Fault running parallel to Centinela Avenue.

Using mostly shallow 4-foot drilling sites, ETI found that methane constituted from 43 percent to 75 percent, by volume, of gas samples in the two largest seeps. “As compared to other regional surveys ETI has conducted over many frontiers and petroliferous basins,” the authors write, “these concentrations are very high.” Much of the gas found exists under high pressure; several monitoring wells dug deeper to around 50 feet in the Ballona aquifer vented so much gas that drilling crews had to evacuate for hours and, in one case, an entire day.

Jones and his co-authors recommend that the best approach “would be to leave these seepage areas open” and not build on them. The second-best option is to construct only “nonresidential buildings within such areas.” All buildings should have gas monitors and venting systems. In high-methane areas, the underground water in the Ballona Aquifer (which in many places contains high levels of dissolved methane gas) should be pumped to the surface, “stripped” of its dissolved methane, and then re-injected back into the ground to prevent the land from subsiding. Although this pump-and-strip technology has been used in other places, it could be prohibitively expensive at Playa Vista, where so much methane has been found. A test unit could be installed, suggests Steinbach, and then the ground near the well monitored to see if the methane level goes down.

By coincidence three environmental groups, Grassroots Coalition, Earthways Foundation and Spirit of the Sage Council, filed suit on April 25 against the city and Playa Capital for not conducting adequate studies of methane back in the 1993 Environmental Impact Report. Citing state environmental laws, longtime Ballona activist Patricia McPherson contends that Los Angeles is legally required to conduct an environmental report on methane and toxic gases. The plaintiffs seek to halt construction at Playa Vista until the study is completed.

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