On Monday, the Ada City Council signed off on a consent order from the Oklahoma Department of Environmental Quality to correct environmental problems at the landfill.
The council unanimously approved the agreement, which requires the city to fix those problems within 150 days or pay a $2,000 penalty. The problems involved seeping leachate — the liquid that drains from a landfill — excessive methane gas and insufficient cover.
The city has already taken steps to address those problems, and additional measures could include putting in additional vents to deal with the methane gas, said City Engineer Gary Kinder.
“We’ve been working on all three of these issues,” he said.
The consent order said staffers with DEQ’s land protection division inspected the landfill in July 2016 and observed the following problems:
• A leachate seep was observed on the east slope. Leachate was also running down the road that allows access to the landfill.
• Methane gas was detected at a monitoring well above the lower explosive limit.
• Blowing litter was observed on the top deck. No litter fences were in use at the working face of the landfill, and no littler collection was occurring during the inspection.
• Exposed trash was observed at the working face, and landfill personnel acknowledged that daily cover had not been applied.
• Solid waste was mixed in with the intermediate cover on the top deck, and an area on the north end of the west slope had exposed waste where there was less than 12 inches of cover.
The agency inspected the landfill again last November and observed the same problems, according to the consent order. DEQ later provided the city with a copy of the inspection report and said it would issue a notice of violation, which was sent in December.
Later that month, the agency notified the city that methane concentrations in three perimeter wells exceeded the lower explosive limit. DEQ asked the city to monitor methane at an adjacent house more often, following detection of low methane levels.
In early January of this year, the city submitted a response outlining its plans to correct the issues at the landfill. The city requested 90 days to finalize the plans and start taking steps to fix the seepage problem.
That same month, DEQ sent another letter asking the city to submit a modified plan to address excessive levels of methane. The agency said four monitoring wells showed concentrations above the lower explosive limit, but methane was not detected at the adjacent home.
DEQ observed seeping leachate on the east and west slopes during a January inspection, according to the consent order. The order said the city had made progress on improving the intermediate and daily cover and controlling blowing litter, but some problems remained.
DEQ summarized the January inspection results for the city and asked the city to submit a plan for addressing the seepage problems within 30 days. The agency gave the city 90 days to address all noncompliance issues.
In early March, the city submitted a short-term plan to replace wind power turbines with solar-powered turbines on top of the gas vents. The city’s long-term plan for addressing the methane problem involved designing a new gas venting system.
The city also proposed fixing the leachate seeps by digging and backfilling trenches with rock, which would allow for better flow and collection.
The same month, DEQ reported that methane concentrations in at least two monitoring wells were still above the lower explosive limit. Later gas monitoring efforts showed that the concentrations were still above the limit.
Based on those findings, DEQ asked the city to update its methane remediation plan to include specific conditions concerning improvements to the venting system and continued monitoring.
DEQ inspected the landfill again in May and found three leachate seeps, according to the order. Intermediate cover on three slopes was not waste-free, but daily cover was in use and blowing litter was controlled.
The city and DEQ discussed the remaining problems in July, which formed the basis for the consent order.
The order requires the city to take steps to ensure leachate remains onsite, continue implementing the action plan for correcting seepage and submit a completion report to DEQ.
Other measures include monitoring gas probes and structures included in the current remediation plan and taking all necessary steps to protect human health. The city shall also submit an updated gas remediation plan within 150 days.
The city is also required to apply waste-free intermediate cover over all solid waste at the landfill.
State law allows DEQ to seek penalties of up to $10,000 per day for each violation of the environmental code, according to the order. In this case, DEQ decided to assess a $2,000 total penalty, but the agency agreed to defer the fine pending the city’s compliance with the order.
Kinder said the city has taken care of many of the seepage problems and is exploring options for dealing with the methane gas levels and the landfill cover.
“We knew this was coming, and we’ve been thinking about it and working on it,” he said. “So now, we’re going to take it to the next level.”