Methane Testing | The Science, Safety and Systems

LADBS Methane Tests are a field study conducted by a licensed LADBS testing laboratory under the LADBS Methane Testing standards. The purpose of a methane test is to establish the methane hazardous classification level based on the Methane Mitigation requirements as outlined in the LADBS Methane Mitigation Standard Plans. The Methane Mitigation requirements will be outlined in the Methane Mitigation Design, which should be implemented during the Methane Mitigation Construction led by a licensed Methane Mitigation Contractor. Ultimately, the Methane Test results will drive the methane mitigation requirements.

A licensed professional engineer or geologist must supervise methane soil gas tests. Ultimately, the LADBS Methane Soil Gas certificate of compliance will require the stamp of the supervising professional engineer. 

What is the Methane Testing Process?

The LADBS Methane Testing process requires onsite fieldwork for which Methane Mitigation research is necessary for preparation. The Methane Mitigation Consultant must establish the methane hazard classifications based on how LADBS has categorized the property. The Methane Hazard Classification can identify as none, Methane Buffer Zone or Methane Zone.

Below is a list of possible Methane Hazard Classifications per LADBS Methane Code

None: According to LADBS, there is no Methane Hazard for this property; consequently, the Methane Testing process will not be required per LADBS.

Methane Zone: The Los Angeles Department of Building and Safety has denoted this area as a possible methane hazard. This classification is likely driven by historical or existing oil drilling.

  • Methane Zone

    Other methane activities could also result in LADBS methane testing, like a Methane producing Landfill or underground Natural Gas reserves. The Methane Mitigation process will be required per the LADBS code, beginning with the Methane Test. Regardless of the methane test results, a Methane Mitigation Design will be prepared by a licensed engineer. The purpose of the methane soil gas test is to establish the extent of methane mitigation that is required. This Methane Mitigation Design will need to be submitted to LADBS for Plan Check, and ultimately the Methane Mitigation Design will be to be implemented during the Methane Mitigation Construction.

  • Methane Buffer Zone

    Defined as the perimeter of the Methane Zone, LADBS established these areas as at risk for methane intrusion, but has defined by LADBS, special methane mitigation requirements our outlined for properties that are situated within the Methane Buffer Zone. Unlike properties within the methane Zone, if the methane concentrations measured during the methane soil gas test are low enough, LADBS may not require methane mitigation.

Methane Testing Process

What will happen on my property during a Methane Soil Test?

LADBS Methane Tests need to be conducted for the LADBS Methane testing standards that have been established by the Los Angeles Department of building and safety. The testing will consist of advancing multiple soil gas probes, which will be installed to monitor methane gas pressure and concentrations. The quantity and depth of these methane soil gas probes function of the property size and the scope of work. 

Shallow soil gas probe shall be placed at increments of one for every 10,000 ft.² of property. Deep soil gas probes shall be placed at one for every 20,000 ft.²

Shallow methane soil gas probes are advanced at 5 feet below the lowest level of the proposed structure. Deep methane soil gas probes are advance a depth of five, 10, and 20 feet below the lowest level of your structure.

For properties less than 20,000 ft.² with the proposed scope of work consisting of slab-on-grade construction, the methane soil gas test will consist of two boreholes with methane swell gas probes placed at 5:10 and 20 feet below ground surface.

Methane Testing with Underground Utilities and Ground Penetrating Radar

After the methane mitigation consultant establishes the scope of work of the Methane Testing, a field visit must be conducted to survey the job site and identify the locations of the methane boreholes. Engineering judgment should be implemented to locate the boreholes in areas that will not affect underground utility lines. Standard subsurface utilities that may interfere with the methane testing boreholes are waterlines, gas lines, sewer lines, and electrical conduits, consisting of low-voltage and high-voltage electricity. Once a job site is surveyed, the proposed borehole location should be marked using chalk paint or a similar semi-permanent delineation tool. Because engineering judgment is not perfect, it is still required to conduct ground-penetrating radar (GPR). This process involves hiring a third-party surveying specialist to scan the underfloor and verify that the proposed methane test borehole locations do not conflict with any underground utilities. The ground-penetrating radar company will collaborate with DigiCert to help establish and finalize any possible underground utilities present. DigAlert is a government-managed company that organizes underground utility companies’ responses to the proposed scope of work that may be conflicting with their utility lines. It is the law to call DigAlert if you are digging during Methane Mitigation construction within Los Angeles. Submitting a DigAlert ticket falls within the responsibility of the Methane testing specialists and Methane Mitigation Contractor.

Direct Push Drilling for Methane Soil Gas Testing

Once the GPR consultant officially clears all utility lines, the drilling team can begin advancing the Methane Testing boreholes per LADBS Methane Testing Standards as established and interpreted by licensed LADBS testing laboratory, and California Licensed professional engineer. A Specialized drilling methodology called Direct Push Drilling is required for these environmental soil gas tests. Direct push drilling minimizes intrusive activities to the soil and sub-surface to ensure that native conditions are disturbed minimally. A licensed drilling contractor must conduct direct push drilling, and specialized drilling equipment must be implemented for use. Direct push drilling can be compared to directly driving a rod into the soil with a hammer. This puncture method is far less intrusive in comparison to rotary-style drilling methodologies.

During drilling, it will be the responsibility of the drilling contractor to place the methane soil gas probes per the LADBS Testing standards. This action must be supervised by the responsible professional engineer to inspect and verify that work is being conducted in compliance with the LADBS testing standards. The construction of a soil gas probe consists of sandwiching a porous plastic vapor probe within a sand layer and sandwiched between two saturated bentonite seal layers. The sand allows for a porous region to promote soil gas migration. At the same time, the bentonite seal is designed to prevent Soil gas borehole leaking and ensure that an accurate representation of methane soil concentrations is measured at the corresponding depth.

Measuring Methane Concentrations During LADBS Methane Test

Methane Testing for a single-family dwelling or an accessory dwelling unit typically consists of two boreholes, each having three soil gas probes installed at five, 10, and 20 feet below ground surface. Methane soil gas concentrations must be measured at the three depths at each borehole as established within the LADBS Methane Testing standards. The methane soil gas concentrations and pressure concentrations must be calculated for two days. 

Results and Conclusions of LADBS Methane Soil Gas Testing

The Methane Test Results will be reviewed, interpreted, and outlined on the LADBS Methane Testing official form called the Certificate of Compliance for Methane Test Data. The Methane Testing results must be submitted to the Los Angeles Department of building and safety for review to establish the Methane Mitigation Design and Methane Mitigation Construction requirements.