STEWART STREET — A new issue is brewing in the neighborhood battle against a proposal to build a train maintenance yard in a historically working-class community, one that involves a giant decades-old pile of trash.

The Pico Neighborhood Association recently raised concerns about the possible dangers of placing the maintenance facility across from Stewart Street Park, which was built on top of a former landfill that releases low levels of methane gas.

“The mixture of methane ground contamination with high electrical voltage could trigger an explosion,” Maria Loya, co-chair of the neighborhood organization, said. “This is a residential community with families where there’s a park, where there’s an elementary school close by.

“It’s a major concern of ours and we want the (Exposition Construction Authority) and city of Santa Monica to push toward some assessment.”

The long-awaited arrival of the Exposition Light Rail to Santa Monica has been celebrated in the traffic-plagued community but has brought headaches for residents in the Pico Neighborhood where there’s support for an electric train line but opposition to the proposed location of a maintenance facility across the street from homes on Exposition Boulevard.

It was more than 70 years ago that a clay company moved onto the corner of Stewart Street and Delaware Avenue and excavated a large pit to make bricks. When the operation ceased years later, City Hall filled the hole with construction waste, eventually covering it with a park.

The landfill today lies beneath the park and approximately 50 percent of the Santa Monica City Yards where City Hall’s own maintenance services, including fleet management, are headquartered and the Santa Monica Fire Department conducts training exercises.

In June of 1998, City Hall launched a landfill gas mitigation system, capturing and treating methane. The system involves a number of wells connected to a pump that sucks the methane out through a straw-like mechanism, running the gas through a series of treatment devices to take out the VOC and other chemicals. It’s then vented through a tower that is 28 feet high into the atmosphere, Dean Kubani, the director of the Office of Sustainability and the Environment, said.

The South Coast Air Quality Management District (AQMD) requires City Hall to run quarterly tests on the perimeter of the landfill to check methane levels, which usually come in under 1 percent. The AQMD requires that levels be kept under 5 percent, which is the lower explosive limit.

Kubani said that the methane level in the landfill is about 5 percent, which he stressed is low for a landfill. Methane levels that exceed 5 percent are considered potentially hazardous.

“It’s a pretty major aggressive treatment system and we’ve been sucking stuff out for 10 years,” Kubani said. “It’s a very low hazard from an environmental point of view.”

Expo officials have studied the methane issue in its environmental impact report, finding that there are no detectable levels on the right-of-way.

“If we do (detect methane) then we would take care of it just like the city has done,” said Monica Born, the project manager for the Expo phase two, which covers the route from Culver City to Santa Monica.

The Pico Neighborhood Association has also raised the possibility of the methane gas traveling via service lines into a facility that would be enclosed.

Linda Piera-Avila, a member of the Pico Neighborhood Association board, cautioned against a similar situation that occurred in the Fairfax District in 1985 when a methane gas explosion at a Ross clothing store injured 23 people.

“All you need is a spark and it’s a re-creation of the ‘85 Fairfax episode,” she said. “It needs to be investigated further and there needs to be an assessment and documentation by an independent expert.”

Kubani said that a city architect reviewed conduits in the area, searching for lines that connect the landfill area to the proposed maintenance site but found none in existence.

He added that there is already activity taking place at the City Yards that would trigger an explosion if the methane gas level was dangerously high, including the SMFD training area where test fires are lit.

“The landfill gas system is really significantly reducing the amount of methane there and treating and monitoring it to ensure there are no significant levels of methane migrating off the site,” he said.