Methane Testing Science, Safety, and Systems
LADBS Methane Tests are a field study that a licensed LADBS testing laboratory completes under the LADBS Methane Testing standards. In fact, the purpose of a methane test is to establish the methane hazardous classification level in accordance with the LADBS Methane Mitigation Standard Plans Methane Mitigation requirements. The Methane Mitigation requirements are available within the Methane Mitigation Design. Consequently, the owner will build the Methane Mitigation Construction led by a Methane Mitigation Contractor. Ultimately, the Methane Test results will drive the methane mitigation requirements.
A 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. Updated January 3, 2023.
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 per the LADBS property categorization. As a result, the Methane Hazard Classification can identify Methane Buffer Zone or Methane Zone.
Occasionally, a methane hazard zone may not exist on a property. As a result, the Methane Testing process will not be necessary. Alternatively, a parcel may have a methane zone or methane buffer zone. In such cases, the property is subject to the methane testing and mitigation process. To illustrate, a list of possible Methane Hazard Classifications per the LADBS Methane Code is available below.
Los Angeles Department of Building and Safety
If LADBS denotes an area as a possible methane hazard, the classification is likely a result of historical or existing oil drilling.
Other methane activities could result in LADBS methane testing. For example, Methane-producing Landfills or underground Natural Gas reserves. Regardless, the Methane Mitigation process will require a Methane Test. According to the methane test results, an engineer will prepare a Methane Mitigation Design. The methane soil gas test aims to establish the extent of methane mitigation. Also, this Methane Mitigation Design will require LADBS Plan Check by an LADBS Mechanical Plan Checker. Ultimately, the specialty contractor will follow the Design during the Methane Mitigation Construction.
Methane Buffer Zone
LADBS defines the methane buffer zone as the perimeter of the methane zone. Moreover, these areas are at risk for methane intrusion, according to LADBS. The methane buffer zone has special methane mitigation requirements per LADBS. However, if the methane measured during the methane test is low enough, LADBS may not require mitigation.
What will happen on my property during a Methane Soil Test?
LADBS requires Methane Tests according to the LADBS Methane testing standards. The testing will consist of multiple soil gas probes to monitor methane gas pressure and concentrations. The quantity and depth of these methane probes are a function of the property size and the scope of work. Further, methane testing experts will place shallow soil gas probes at increments of one for every ten thousand square feet of property.
The methane engineer place deep soil gas probes at one for every twenty-thousand square feet. Shallow methane soil gas probes are five feet below the lowest level of the proposed structure. Deep methane soil gas probes are at a depth of five, ten, and twenty feet below the lowest level of your structure. Accordingly, properties less than twenty thousand square feet will consist of two boreholes with methane probes at five, ten, and twenty feet below the lowest level of the structure.
Methane Testing with Underground Utilities and Ground Penetrating Radar
Environmental field technicians identify the locations of the methane boreholes during a site survey. The methane mitigation consultant establishes the scope of the Methane Testing before the Site Survey. Thereafter, engineers use their judgment to locate the boreholes in areas that will not affect underground utility lines. Subsurface utilities that may interfere with the methane boreholes are waterlines, gas lines, sewer lines, and electrical conduits. Electrical conduits can consist of low-voltage and high-voltage electricity. The borehole location will be marked using chalk paint or a semi-permanent delineation tool.
Geophysical Survey Options During Methane Mitigation Planning
Because engineering judgment is imperfect, conducting ground-penetrating radar (GPR) is still required. 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 conflict 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
The drilling team can advance the methane testing boreholes once the GPR consultant clears all utility lines. Boreholes will be built per Methane Testing Standards by an LADBS testing laboratory and California professional engineer. Consequently, these environmental soil gas tests utilize a special drilling methodology, direct push drilling. Direct push drilling minimizes intrusive activities to the soil and sub-surface to ensure that native conditions are disturbed minimally. A drilling contractor will use special equipment to advance the direct push drilling boreholes. Direct push is a drilling method similar to hammering a rod into the soil. This puncture method is far less intrusive in comparison to rotary-style drilling methodologies.
Soil Gas Probe Construction
The responsible professional engineer will supervise, inspect and verify the methane testing work. The methane testing work and soil gas borehole construction must be per LADBS testing standards’ specifications. During drilling, it will be the responsibility of the drilling contractor to place the methane soil gas probes per the LADBS Testing standards. The construction of a soil gas probe consists of sandwiching a porous vapor probe within a sand layer. And sandwiching the sand between two bentonite seal layers. The sand allows for a porous region to promote soil gas migration. Concurrently. Moreover, the bentonite seal will prevent soil gas seepage. Consequently, the bentonite will ensure that accurate methane soil concentrations 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. Furthermore, each borehole will have three soil gas probes five, ten, and twenty feet below the ground surface. Engineers record the Methane soil Gas measurements at the three depths of each borehole. Again, testing complies with the LADBS Methane Testing standards. Field Scientists monitor the methane soil gas and pressure concentrations during two days.
Results and Conclusions of LADBS Methane Soil Gas Testing
The LADBS Methane Testing official form is the certificate of compliance for methane test data. The certificate of compliance will outline the results of the Methane Test. LADBS will review to establish the Methane Mitigation Design and Methane Mitigation Construction requirements after reviewing the methane test results.