The Oregon Department of Environmental Quality is continuing to work with the owner of the former Johnson Creek Landfill property, Emmert International, to investigate residential properties near the former landfill. The initial subsurface monitoring results in June of 2019 indicated high concentrations of methane gas at the northeastern border of the landfill property. Two of the three monitors at that border had results above the level at which methane becomes a concern. High levels of methane can be flammable or, in a confined space, displace oxygen that we depend on to breathe.
Because of the elevated methane levels at the northeastern border of the landfill property DEQ worked with Emmert to expand the investigation to include the nearest residential properties.
First, DEQ worked with Emmert and their consultant, Black Mountain Consulting, to develop a systematic plan to guide the methane testing on residential properties. Then, DEQ worked with Emmert to reach out to property owners for access agreements. The plan for the investigation included a map of the test area, test locations within that designated area of interest and detailed procedures for conducting methane testing. Testing on residential properties took place in late summer and fall of 2019. Test locations included crawl spaces under homes, out buildings, manholes, utility vaults, and temporary soil-gas monitoring probes in residential yards.
Black Mountain tested the confined spaces and soil probes numerous times but did not detect methane at any test location on residential properties.
What are the next steps?
Due to the COVID-19 concerns this additional testing has been delayed until it is safe to proceed on residential properties.
Although this methane investigation had favorable results DEQ identified potential gaps in the test coverage and asked Emmert International to conduct testing at several additional locations, including nine subsurface utility vaults, previously untested residential yards and a vacant building. Some of these locations are slightly outside the original area of interest planned for the methane investigation.
Subject to appropriate health and safety precautions agreed to by the residents, DEQ , Emmert and Black Mountain, Black Mountain will reach out to property owners for access agreements as they have done previously. Black Mountain may request property access for the following types of monitoring:
- Installation of temporary monitoring probes outside on your property. To see if the methane is moving in the ground, Black Mountain may want to put some methane probes into the ground by your home. You do not have to be home for this installation, but staff will want to discuss with you where the probe(s) will go.
Frequently asked questions
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.