The City of Los Angeles sits on top of an oilfield, and the city is full of closed oil rigs. Over time, these rigs and other drilling sites from the oil drilling days can leak methane. Methane is a harmful gas that can be hazardous in high concentrations, even fatal to humans.
The Los Angeles Department of Building Safety (LADBS) requires methane testing on structures within certain designated high-risk or elevated risk areas. These at-risk areas, known as methane zones and methane buffer zones, are published on a map produced by the LADBS, but it is also available on city zoning and planning tools like ZIMAS and NavigateLA.
If your property falls within a City of Los Angeles methane zone, you will need to have a methane test before you do any construction, remodeling, or renovation. It is critical you find a qualified environmental engineering and consulting company that can guide you through the test and ensure you comply with city ordinances and regulations. These are some of the questions you should discuss with your engineering company before beginning the methane testing process.
How will the test be conducted?
Any methane soil gas test must be conducted according to the regulations and requirements developed by the City of Los Angeles. The city requires that probes be sent down 5, 10, and 20 feet into the ground beneath your property to measure the levels of methane gas present at those depths. The results are reported back to the city for mitigation and documentation purposes.
To send the probes down to those required depths, boreholes must be carefully drilled to get accurate readings and comply with the regulations laid out by City Ordinance in the LADBS Methane Testing Standards.
Do I need both a shallow and a deep methane test?
Both shallow and deep methane tests will need to be conducted on your property in almost all cases. It is better not to think of them as two separate tests but as two phases of the same test; they’re both conducted to find the area on your property with the highest concentration of methane gas.
Shallow Methane Test
The City of Los Angeles requires that every property have at least two separate shallow methane tests, or for properties larger than 10,000 square feet, one test per 10,000 square feet. These shallow tests are used to find areas of higher methane concentration on your property and to choose a suitable place for the deep methane test.
Deep Methane Test
A deep methane test or Deep Gas Probe will be drilled wherever the highest methane concentration was found during the shallow methane tests. City ordinance requires that every property also have a minimum of two separate deep methane tests but only requires one per 20,000 square feet of property.
Bores are drilled into preselected areas to at least 20 feet below the property’s lowest point or elevation. Methane sensing probes are installed at the 5, 10, and 20-foot mark and left to record data over a 24-hour period.
While this might seem like a lot of testing, it is all required by the LADBS, and failure to follow the rules precisely can result in the test being rejected by the department.
Is there a risk my utilities might be affected or damaged?
Many properties have buried electrical, fiber optic, gas, and water lines. The single largest risk associated with an LADBS methane test comes from hitting, damaging, or rupturing one of these lines. The resulting damage could be as small as a brief interruption of telephone service or as dangerous as a serious water leak or a gas explosion.
DigAlert is a non-governmental organization deputized by California state law to ensure safety when digging into any area where underground utilities might be present. Before any drilling can happen, DigAlert must be notified. They notify all relevant utility companies and providers to come to your property and mark out the location of their pipes and wires.
While this usually is more than sufficient to ensure no damage is done, it is also recommended that any drilling sites be investigated with Ground Penetrating Radar (GPR). This is a form of radar that looks for objects or obstructions underground. If anything is found using GPR, a different, more suitable site for drilling can be selected.
Will there be a lot of drilling? Will you use direct push drilling?
The environmental engineering company will need to drill to conduct both shallow and deep methane tests. The drilling techniques are designed to be minimally invasive and aim to cause as little disruption as possible.
One of the best ways to bore the necessary holes is to use direct push drilling. There are a few different types of push drilling, and many people are curious about what is direct push drilling? And why is it seen as the best solution?
Direct push drilling uses the weight of the drilling machine combined with a powerful hydraulic hammer to drive the drilling bit directly into the ground without the need for large drill bits or cumbersome manual drills.
Direct push drilling is the fastest, safest, and most effective way to drill the methane test boreholes in accordance with LA city regulations. It does what is necessary for the test but minimizes the impact on your property.
What steps will I need to take once I know the results of the methane test?
After the methane probes have taken 24 hours’ worth of information, the data is recorded and assessed by your environmental engineering firm. Your property will be given a Methane Mitigation Hazard Classification based on the readings and results. The classifications run from levels 1 to 5.
Your environmental engineering firm can help you understand the different levels and how they impact your property. Different levels require different modifications to existing buildings and any new buildings on the site.
The methane mitigation construction procedures depend both on the classification level as well as factors such as whether the building is naturally or mechanically ventilated, the intended use of the building, distance to pedestrian footpaths if there is groundwater on the site, if the building has a raised or sunk foundation, and the presence of any flammable materials.
It is possible that methane testing will reveal an issue that could require fairly substantial mitigation work to bring the property into compliance, or it could be much less. Your environmental consulting firm will walk you through what steps you may need to take.
Arroyo Geoscience Your Resource for LADBS Methane Testing
Arroyo Geoscience is a hybrid engineering contracting company that bridges the gap between site geotechnical and environmental testing and the contracting needed to mitigate any issues found on your property. We are a complete solution to all your methane testing and mitigation needs in the Greater Los Angeles Area.
Contact the methane mitigation experts at Arroyo Geoscience today to understand what methane testing you need to comply with your local laws. Call us at 818-967-5977.