Methane (CH₄) is a colorless, odorless, tasteless, flammable gas that is widely distributed in nature. Methane Gas is produced whenever organic material is decomposed by bacterial action in the absence of oxygen. The atmosphere contains about 2.2 ppm by volume of Methane.

Methane Gas Entry into Homes and Commercial Buildings

    Like Radon, Methane gas can migrate significant distances under the ground surface and be forced into adjacent buildings by the pressure gradient between the soil and the building interior. Points of entry include floor/wall cracks, floor drains, sewer pipe entry points as well as utility access penetrations. Gas can accumulate inside wall cavities, crawl spaces, and inside sumps and poorly ventilated basement areas.

Active or Closed Landfills

    The EPA and some specific states (especially New Jersey) have regulations which require landfill owners to control methane in soil gas from migrating to the property boundary. New Jersey requires quarterly perimeter boundary testing usually using gas monitoring probes installed a minimum of 3 feet below ground level.

Methane Toxicity:  Fire/Explosion Risk

     Methane gas is relatively non-toxic; it does not have an OSHA PEL Standard. Its health affects are associated with being a simple asphyxiant displacing oxygen in the lungs. Miners previously placed canaries in deep mines to check methane gas levels. Reportedly, canaries keeled over at about 16% oxygen indicating it was time to leave.

    Methane is extremely flammable and can explode at concentrations between 5% (lower explosive limit) and 15% (upper explosive limit). These concentrations are much lower than the concentrations at which asphyxiant risk is significant. Reportedly, the most violent methane explosions occur at concentrations of about 9%; coal mines are hence kept well ventilated (pumped with fresh air) to maintain methane levels at or below 1%.

Methane as Fuel:  Green Energy Source

     Tens of thousands of gas wells have been installed in the states of PA, WV, MD and VA to extract methane from the Marcalleus Shale in the Allegheny Plateau. From AET's knowledge, little if any methane gas concerns have occurred from methane gas migration into adjacent properties. Once released into the atmosphere, methane gas is quickly dispersed.

    However, AET's Western, PA office is knowledgeable regarding concerns which have been raised associated with contamination of the groundwater and surface water due to the significant quantity of water and additives used during drilling operations. Significant solid waste/drill spoils are also generated which must be removed and disposed. 

Case Study:  New Jersey Bank Facility

     Recently, AET investigated a bank branch facility built on an abandoned landfill. The property operated with a deed restriction and was equipped with a methane gas detector alarm system. During a routine property inspection, a New Jersey state inspector questioned the frequency and validity of calibration of the installed gas detector. This was an easy one to respond to, since the detector had an inspection sticker on its side. Annual service and calibration was part of the purchase cost of this equipment provided by the manufacturer.

     Remember, once installed, monitors must be regularly inspected and calibrated to insure they are working properly and accurately. Methanealarms are a useful tool but require routine maintenance. Having the equipment manufacturer provide these tasks (at least annually) under a service contract is a WIN-WIN.

Detector Placement/Location

     Methane gas is lighter than air and the highest concentrations inside buildings are found near the ceiling. The Methane detector should be installed no closer than 6 inches from the ceiling and away from dead air spaces such as corners.

     Conversely, propane gas is heavier than air and accordingly will sink and accumulate at floor level. Propane gas detectors should be placedon the wall 2 feet from the floor and at least 2 feet from any corner.

     Carbon monoxide is about 3% lighter than air and at normal room temperature will disperse uniformly in all directions throughout the room.Install your CO alarms within 40 feet of all rooms used for sleeping purposes, especially near furnaces, hot water heaters, fire places, etc.

Proper placement of detectors
can save lives!

How AET Can Help You

     AET's environmental professionals are experienced in methane detection and controls. Testing can be performed below the surface of the soil at the boundary of the property or immediately outside the foundation of on-site or off-site buildings. Direct reading measurements are also taken at potential points of entry inside the building including confined spaces such as wall cavities, crawl spaces and sumps/manholes. Remember, methane gas does not have any odor or other sensory warning properties. The odor from natural gas from leaking lines or valves is the result of an odorant (Mercaptan) which is added to the gas by the supplier.

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Call 800-9696-AET or 610-891-0114 
to discuss any environmental concerns

Alan Sutherland has been a Certified Industrial Hygienist since 1978 with over 30 years of CIH-related environmental consulting experience. He has aMasters Degree in Environmental Science from Drexel University and is the founder/owner of Accredited Environmental Technologies, Inc. (In 1984). He is uniquely trained and licensed as an Environmental Professional in both the field and laboratory. He has been the founder of two AIHA Accredited Laboratories and a mentor to six (CIHs). Mr. Sutherland is also a Certified Hazardous Material Manager. He can be reached directly at 610-891-0114 or email a.sutherland@aetinc.biz.

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