Methane gas has been prominent in the news recently. In May, the Los Angeles Times featured a story on leaking gas company pipelines:
Methane in our region can originate from leaking pipelines, old landfills, or natural sources. Los Angeles has oil and gas fields and plenty of naturally occurring methane within our region. Because of the region’s natural methane sources both the County of Los Angeles and the City of Los Angeles have their own rules and requirements for development and redevelopment projects. The requirements differ if your project is within the City or the County jurisdiction but both are intended to protect health and safety of workers on the project and the surrounding community. It is critical to cover this safety concern during your project planning as well as project activities.
During subdivision grading near the Castaic Lake area, an Alta client noticed hydrogen sulfide bubbling up in surface groundwater. Alta was called in to determine both the extent and source of the issue. We conducted monitoring and used isotopic analysis to determine the origin of methane gas. It was found to be naturally occurring and originating from deep in the ground near a fault zone. Our client modified development plans to build methane safe housing as a remedy.
In another example, one of our clients identified a potential problem during soil trenching. Alta was called out to investigate and found explosive levels of methane, as well as, asbestos and construction debris in the trench soil. The presence of debris was indicative of landfill material. While the construction project was on a former landfill site, we were ultimately able to pinpoint the origin of methane to be a leaking gas company line. The gas company repaired the lines and construction was able to move forward.
Construction projects with confined or enclosed spaces are of particular concern as they can fill with methane and create an explosive potential. Over the years in Los Angeles, explosions have occurred, even outside the designated methane buffer zone. It is important to use utmost caution, particularly during demolition and construction activities.
Methane is a non-CERCLA issue and many times Phase I reports will not include a consideration of methane. This is a critical safety concern, there is a lot of information available in Los Angeles because of the oil and gas fields. As a part of plan check for your permit of development you get instructions if you are in a methane zone or buffer zone or in an oil & gas field. If you are starting a development or redevelopment project, take a look at the information available through both the County and the City of Los Angeles. Know where your project is relative to methane zones or buffer zones and take precautions relative to potentially leaking gas company lines.
If you have questions, we can help. Contact David Schack, Vice President Building Sciences at (562) 495-5777 or firstname.lastname@example.org.