County landfill monitoring shows fewer contaminants but DEQ permit revision and public notice required

County staff updated the Board of Supervisors on June 23 about the landfill groundwater monitoring program and progress under the corrective-action monitoring plan.

Staff said the number of analytes exceeding groundwater protection standards has fallen since 2008 (from roughly 10–12 to eight analytes in recent monitoring). "When you compare from May of 2008 to this last May in 2026 ... we are down to eight," the presenter told the board during a slide-assisted update, and said concentrations in most wells have trended down, though decreases have slowed and some wells—particularly one labeled NW8—have had longer-term issues.

The presenter said DEQ (the state Department of Environmental Quality) sent a March 5 letter and that DEQ has approved earlier assessments including the installation of MW21 on adjacent property. As a result staff interpret DEQ's letter to mean additional offsite drilling may not be required. Staff said the county must revise the corrective-action permit, post it in the public depository and submit it to DEQ; they identified a roughly September 5 timeframe to complete that administrative step.

Staff discussed the program's current approach—monitored natural attenuation and source control (site closure, cover systems, gas collection)—and described interim measures and spot treatments used at localized drain areas. The board and staff also discussed hydrologic variability: drought-driven drops in the water table can increase measured concentrations even when overall mass is not increasing.

What happens next: staff will prepare and circulate a revised corrective-action permit, bring suggested optimizations for DEQ consideration in the next four-year case report, and return to the board with proposed interim measures or source-control actions if necessary.