Cowlitz County outlines landfill upgrades, leachate fixes and capacity plans

Cowlitz County solid-waste staff on Monday told the board they are accelerating infrastructure work at the county landfill to address leachate-line failures, improve gas collection and expand capacity ahead of planned cell construction.

The solid-waste presenter said crews restarted a vertical-well installation last week to augment horizontal wells and increase methane extraction, noting the project will add “a little over 20 vertical wells” and carries a price tag of about $1.4 million. She said the wells will tie into the landfill flare system for combustion while the county finishes other upgrades.

The work follows a March leachate-line failure. Staff emptied the north pond, found significant sludge and scaling between the pond and pump house, and plan mechanical cleaning in mid-June to reduce the risk of future line failures. To prevent future blockages, they are evaluating added cleanouts and a tracked pipeline "pig" that can be fitted with a locator. Staff described tracker options ranging from a few thousand dollars for a temporary wand to roughly $8,000 per permanent sensor; a basic tracked pig deployment, they said, could run about $10,000 to start, while installing multiple permanent sensors and cleanouts would be a larger capital expense.

“We stopped that project last fall because of rain and restarted yesterday,” the solid-waste presenter said of the vertical wells, and later described the pig-tracking technology as a low-cost test option before committing to permanent sensors.

Staff also outlined longer-term capacity work. The county plans a third leachate pond (about 5 million gallons) to double on-site storage and is advancing design for cell 10, a roughly 14-acre landfill cell scheduled for 2027 construction. The estimated cost to complete cell 10 — liners, leachate conveyance and related systems — was presented at about $27.5 million with a target completion in fall 2027.

Separately, staff warned the existing Tenant Way flare is at the end of its useful life and generates frequent alarms; initial procurement produced bids with irregularities, so staff said they will return to the board to recommend rejecting the bids and rolling the flare purchase into the larger construction contract. The county has closure funds set aside for the replacement.

Why it matters: the repairs and upgrades focus on regulatory compliance (air permits and leachate discharge limits), operational continuity and long-term capacity. Scaling in leachate lines has already caused a multi-week outage, and staff said addressing it now will reduce emergency repairs and protect downstream treatment partners.

Next steps: staff will proceed with the planned pond cleaning and pilot pig deployment, return to the board to seek formal authority to reject flare bids and include the flare in the construction bid package, and continue six-year plan project alignment for cell 10.