Oregon Department of Environmental Quality is working with the owner of the
former Johnson Creek Landfill property, Emmert International, to further
investigate recent results indicating high concentrations of methane gas at the
northeastern border of the property.
subsurface soil monitoring found high levels of methane along the northeastern
border of the property. Two of the three monitors had results above the level
at which methane becomes a concern. These may be stagnant pockets of methane
gas or the methane may be more mobile.
levels of methane can be flammable or, in a confined space, displace oxygen
that we depend on to breathe.
is working with Emmert International to conduct additional testing to determine
this and subsequently establish the best course of action. Testing will take
place on adjacent residential properties.
Sept. 13, 2019
International has hired a consultant, Black Mountain Consultants, to do the
technical work. Black Mountain and DEQ have reached out to residents identified
in the monitoring plan and have assessed confined spaces on most of the
properties. No methane has been detected in these confined spaces.
Mountain is still working to temporarily install monitoring probes in the soil
outside of these residences. The soil in this area quickly turns to gravel and
it is hard to put the probe down as far as it needs to go. Black Mountain is
currently evaluating other technology options. So far only two soil probes have
been successfully installed and they did not detect any methane.
and Black Mountain will be continuing to do monitoring for at least the next
month until we complete the monitoring and characterization and determine if
any methane is coming from the landfill.
High levels of methane can be flammable or, in a confined space, displace the oxygen that we depend on to breathe. The initial high methane results were found only on the former landfill property and DEQ is working with the property owner’s consultant, Black Mountain Consultants, to understand whether to methane is traveling through the soil.
When DEQ permitted the landfill in 1971, the landfill was allowed to accept construction materials. These types of woody debris take longer to decompose than landfills that accept things like food waste. Therefore, the release of methane can be delayed.
DEQ was investigating methane on the property as a result of questions raised about the site in 2016. DEQ followed up with an investigation evaluating 53 locations on the property and found some detections of methane near the vents on the east side of the building and indication that pockets of methane may still exist in the landfill. This led DEQ to test inside of light poles in this area of the property. Light poles represent confined spaces with a spark source. Two light poles along the northeastern boarder were slightly below the level at which DEQ would be concerned. Following those results, three probes were installed along the eastern border of the former landfill. The northernmost of the three probes (MW-4) and the middle probe (MW-5) tested above the level at which DEQ would be concerned.
The investigation will take place on adjacent residential properties, going two rows of homes to the east for a total of 10 homes. Black Mountain Consultants will be requesting property access for real-time in-home and exterior monitoring of confined spaces, such as basements, crawl spaces and outbuildings. They will also be placing monitoring probes in the soil to check for the presence and movement of methane.
It is not yet clear if the methane is just a pocket or if it has moved through the soil. Since methane displaces oxygen, if a significant amount of methane was moving through soil you would typically see distressed plants and trees. There have not been any such indications. At this time, DEQ does not think that this methane poses an immediate risk. Black Mountain Consultants’ investigation will provide more definitive results.
That would only occur if methane existed at a concentration that would be flammable (five percent or higher) or at the point when it would displace oxygen (15 percent or higher). DEQ does not think that such results are likely. Black Mountain Consultants’ investigation will provide more definitive results.
Black Mountain Consultants will start reaching out to homeowners for access agreements the week of August 26 and conduct in-home testing as soon as they can obtain the access agreements.
Some enclosed spaces may be accessible to the methane if it is moving through the soil. The lack of ventilation in these spaces make them places where methane can accumulate. If methane accumulates above a concentration of 15 percent, it can displace the oxygen that we depend on for breathing.
While methane is not toxic, it can be flammable or displace oxygen. For that reason, any amount of methane in the home will need to be assess and corrected as described below.
Any corrective action related to methane moving through the soil will be done on the former landfill property. Such measures might include a vacuum that can remove methane from the ground or collection and ventilation systems that slowly release methane into the air.
If any methane is discovered in someone’s home, the consultant will work with the resident to ventilate the space and continue to test the space with the handheld monitor until they can confirm that the gas has dissipated. They will work with the resident to determine how to keep the space ventilated and confirm the source of the methane.