Methane gas test probe installation is a professional service that provided by Diversified Drilling Inc. (DDI) Company. Through this service, consulting companies could detect Methane gas existing and its concentration as a potential combustion hazard in the soil of many Southern California lands. ( Click here to see other services.)
Methane Gas Test is mandatory prior to development in a Methane Zone Areas. This areas indicates in Methane Buffer Zone in Los Angeles map , City of Huntington Beach and some areas in Orange County. Areas with susceptible potential of high methane gas concentration include: Former Oil Fields, Landfills and areas with high natural petroleum deposits.
The data will collect from methane gas testing. These data help building departments in health and safety determinations and mitigation requirements to reduce the risk of explosion in such Methane Zones.
The work plan for site testing summarizes in three primary steps: 1 – Schedule Site Testing 2 – Conduct Shallow Soil Gas Test 3 – Conduct Gas Probe Test
The site testing results from these steps will organize in a report and include with the building permit application. Site testing shall conduct three steps respectively. The following three-step testing protocol will determine the concentration and pressure of the subsurface methane gas. In conclusion, the report will assist the consultant companies to design of methane hazard mitigation systems.
Step1- SCHEDULE SITE TESTING
Site Testing should schedule before any site grading. If Site Testing after site grading is unavoidable, then Site Testing shall be conducted at least 30 days after any site grading.
Step2- CONDUCT SHALLOW SOIL GAS TEST
Methane gas concentration measurements for the Shallow Soil Gas Test shall take as follows:
1- A minimum of two per project site, and at a rate of one sample per 10,000 square feet of site area, or portion thereof. However, the site area of very large sites may calculate as the area of the building footprint plus the area within 100 feet of the building perimeter. 2- At a depth of not less than 4 feet below ground surface, or 3- If groundwater finds less than 4 feet below ground surface, then the depth of the Shallow Soil Gas Sample shall take above the ground water level.
The methane gas concentration data from the Shallow Soil Gas Test and site observations shall review to identify locations where high gas concentrations of methane gas may find. Above all, Shallow Soil Gas measurements shall make by professionals at least once and may take at anytime before the installation of Gas Probe Sets.
Step3- CONDUCT GAS PROBE TEST
The location of Gas Probe Sets shall be based on the information from the Shallow Soil Gas Test. Accordingly, this location is usually at the place with the highest concentration of soil gas. Methane gas concentration and pressure measurements for the Gas Probe Tests shall take as follows:
1- The minimum requirement is one gas probe set for every 20,000 Sqft or portion thereof of site area. Regardless of area, all sites shall install a minimum of two gas probe sets. 2- The site area of very large sites may calculate as the area of the building footprint plus the area within 100 ft of the building perimeter. 3- Each Gas Probe Set shall consist of three probes, installed at approximate sampling depths of 5,10 and 20 ft below the elevation of the lowest building slab or footing. 4- Gas Probe Sets shall install a minimum of 12” above ground water table. 5- Gas Probe Sets should never install below the ground water level. 6- Shallow Soil Gas data, collected as described in Step 2, may use in lieu of Gas Probe Set data when ground water is found less than 5 ft below the ground surface.
Record data from the Gas Probe Sets as follows:
1- Two sequential measurements are the routine that will take, with a minimum 24-hour interval following placement of the Gas Probe Sets. Samples shall not collect during increasing barometric pressure from a pre-frontal weather condition. 2- Site testing data shall record on Form 1 – Certificate of Compliance for Methane Testing Data and certified by the engineer.
DDI has expert staffs to assist you with Methane Zone’s sampling requirements. We usually provide our Methane gas test using Direct Push drilling system to achieve fastest results. This service offers for developers and home owners to have better idea in this issue.
GAS PROBE FOR METHANE GAS TEST EQUIPMENT SET-UP
SHALLOW METHANE GAS TEST EQUIPMENT SET-UP
Source: City of Los Angeles "SITE TESTING STANDARDS FOR METHANE"