details on the EPA Inspection of Coffin Butte Landfill which Revealed Accumulation of Flammable Methane Gas, Multiple Exceedances of Methane Limits
Following up on the recent Statesman Journal article on significant issues around Coffin Butte landfill, I’m providing the details of the EPA Inspection Report that was highlighted in the article.
First, a bit of background: certain municipal solid waste landfills are required to follow EPA/state emissions regulations which include conducting surface emissions monitoring in certain parts of the landfill four times a year, and installing a gas collection system in certain parts of the landfill sufficient enough to capture gas (40 C.F.R. Part 60, Subpart WWW; 40 C.F.R. Part 62, Subpart OOO; 40 C.F.R. Part 63, Subpart AAAA; 40 C.F.R. Part 98, Subpart HH).
A very small fraction of landfills in this country appear to be inspected. The U.S. EPA does not have nearly enough resources to conduct inspections of all landfills. And state regulators, though responsible for air permits and landfill emissions regulations, do not have staff capacity or expertise to inspect landfills. Through a public records request, we received an EPA inspection report on Coffin Butte Landfill.
The EPA performed an announced clean air inspection of Coffin Butte landfill on June 23, 2022. Republic Services owns Coffin Butte. According to the report, the landfill began as a military dump in the 1940s. It receives approximately 3,500 to 4,500 tons per day of waste. Wastes received include municipal solid waste, petroleum contaminated soils, construction and demolition (C&D) waste, C&D material recovery facility (MRF) residuals, and other industrial wastes. The report notes that final cover on the Landfill is compacted soils with a synthetic membrane, with penetrations booted and plastic welded. Interim cover is at least 24 inches of soils. Much of the interim cover area is covered in tarps or, in areas without work planned for a few years, a thicker layer of EPDM. In both cases, this is with the primarily goal of reducing water infiltration into the Landfill. Daily cover is 6 inches of soil or approved alternative daily cover (ADC). Republic uses C&D MRF shaker fines, MSW incinerator ash, and tarps as ADC at the Landfill.
The report further outlines that the landfill collects around 25 to 30 million gallons of leachate each year. Leachate flows by gravity to sumps and is pumped to covered storage ponds. Leachate is trucked to local publicly owned treatment works. Not surprisingly, no leachate is recirculated, and no liquid wastes are added to the Landfill. The gas collection and control system (GCCS) contains over 300 landfill gas (LFG) collection points, including horizontal wells, vertical wells, and parts of the leachate system with gas collection. Collected landfill gas partially routed to a separately owned/operated gas to energy plant run by PNGC Power.
The EPA surface emissions monitoring inspection found very troubling results:
Extreme methane limit exceedances: Quoting from the EPA report, “Over the course of the day, Daniel Heins identified 61 points in exceedance of 500 parts per million (ppm), exhausting his supply of marking flags. Of these, 21 flagged exceedances were above 10,000 ppm. Many flagged exceedances represented clusters of exceedances at multiple points or broad areas of exceedances. Of the flagged exceedances, 26 were at or partially at gas collection wells (including both active and abandoned or decommissioned). Eight exceedances were at leachate cleanouts. Daniel Heins focused monitoring on areas under intermediate cover, though the first six exceedances were in final cover areas. During the afternoon monitoring, Daniel Heins measured multiple exceedances that continued to be above 500 ppm multiple feet in the air, with multiple feet lateral distance from the emission source, indicating substantial landfill gas plumes.”
Discrepancies between Republic’s reported monitoring and what the EPA found: Quoting directly from the report, “Daniel Heins expressed potential concerns with Republic’s SEM/Method 21 procedures. Despite Republic having seen no more than 6 exceedances in the recent SEM reports supplied ahead of the inspection that included penetration monitoring, including reports with 0 exceedances, he identified 61 points in exceedance of 500 ppm, including 21 points above 10,000 ppm, with 26 exceedances at gas collection wells that Republic should have specifically been monitoring on a quarterly basis since the Oregon State Plan became effective in November 2020. “
Maxed out readings of methane, visibly inflated tarps, indicating an accumulation of flammable gas - potential safety concern: Quoting directly from the report, “Flag #51 was by a broad area where the tarp was visibly inflated with gas. The tarp was not moving in the wind, it looked to be being pushed out steadily over a wide area towards the top of the south slope on the central area of the landfill, being held down by straps, cover anchors, and sandbags. Neither Daniel Heins nor Phil Caruso could identify any place where the wind could be lifting under the tarps, as the tarp edges were sandbagged and staked down. Daniel Heins measured a concentration of 2% at flag #51 before pulling away to avoid maxing out his instrument. He measured the methane concentration to be 2000 ppm at 3’ in the air at this location, indicating a plume of gas coming out from the inflated tarp area. Along the top of this section of tarp, from flag #52 to #54, every post or tarp hole Daniel Heins monitored exceeded the surface methane standard, with readings of up to 7% shown before the instrument maxed out.”
“Daniel Heins expressed concerns with the areas of tarp that were inflated with and leaking out landfill gas, as detected during the SEM, noting that in additions to compliance concerns with the surface methane standard that such an accumulation of flammable gas creates a potential safety concern.” Republic disputed that the tarps were inflated with landfill gas, claiming that the wind has blown them up.
There were clear differences in how Republic did surface emissions monitoring in compliance with EPA regulations, as opposed to the EPA inspector, resulting in finding less exceedances than the EPA. The Republic representative’s responses were documented as follows in the report:
“Phil Caruso did not dispute any of the readings, though noted that he would not have checked many of the exceedance locations, that he would have spent less time monitoring, or that he would have considered a higher location to be “the ground” when placing his probe 5 to 10 centimeters (cm) above the ground per the SEM regulations.”
“At an exceedance (flag #1) with a hole in the ground from an animal burrow, Phil Caruso stated that he would have considered the “ground” to be where the ground would have been if an animal didn’t dig a hole into it at that location, rather than the ground at the base of the hole, and thus measured from a significantly higher location than Daniel Heins.”
“At an exceedance (flag #2) between overlapped tarp material, with one piece of tarp raised above the other with a gap of air in between, Phil Caruso stated that he would have monitored with his probe above the upper tarp, rather than measuring the 5 to 10 cm from the tarp against the ground.”
“When Daniel Heins was monitoring a cluster of decommissioned wells with a patch of distressed soil (flag #3), Phil Caruso stated that he would have moved on after not directly getting above 500 ppm within twice his instrument response time even if there was an increase in reading, rather than moving around the penetration points slowly to find maximum reading point and then waiting twice the response time at this maximum reading location.”
“When Daniel Heins was monitoring at leachate cleanouts, Phil Caruso stated that he does not monitor at these and that they are not fully penetrating the cover. Daniel Heins responded that it was likely that many of these ultimately did penetrate the cover, especially in areas of thinner intermediate cover, and that regardless he recommended checking these as they were proving to be repeated sources of extremely elevated emissions, many over an order of magnitude above the surface methane standard. Phil Caruso stated that he was not required to monitor these. Daniel Heins and Phil Caruso had a similar discussion at the valve box dug into the cover with a reading of 4% methane (flag #37), with Phil Caruso stating that this was not a penetration and thus he did not have to monitor this.
“When Daniel Heins was monitoring at a horizontal penetration of the cover associated with a well (flag #16), Phil Caruso stated that he would not have monitored this as a penetration.”
“Phil Caruso stated that he would not have monitored the Cell 5 leachate riser that Daniel Heins measured multiple exceedances at, as it was outside of the waste mass.”
“For cover integrity monitoring, Republic stated that they look for holes and cracks in the soils and wind damage on the tarps, but that there was no set answer for what degree of tarp damage would necessitate repair.”
