Residents, consultant urge caution over proposed solar on closed Middlesex landfill as vinyl chloride remains above safety standard

Thomas Major, a Saluda resident, urged the Middlesex County Board of Supervisors on Sept. 9 to pause plans for a solar project on the county’s closed landfill until groundwater contamination has fully met state standards.

Major said vinyl chloride — a volatile organic compound identified in past monitoring — remains “five times higher than what are considered safe” in some wells and that the site must be below the groundwater-protection standard for three consecutive years before monitoring can stop. He called vinyl chloride “a Group A human carcinogen” and asked the board to halt the project until the Department of Environmental Quality (DEQ) has released the site from monitoring requirements.

The board then heard an update from ARM Group (formerly Resource International), the county’s environmental contractor. Bob Hundley of ARM Group reviewed groundwater and landfill-gas monitoring data at the site and said most monitoring wells show improvement but that one well — identified in ARM’s presentation as NES-2R — still records vinyl chloride concentrations above the DEQ groundwater protection standard. Hundley said levels have declined since December 2024 and June 2025 samples and are “trending downward,” but he noted the site remains above the regulatory threshold and that achieving the regulatory exit condition could take time.

Hundley outlined the county’s current approach: semiannual groundwater sampling, annual reporting to DEQ, and monitored natural attenuation. He said the county could pursue active remediation options (for example, in-situ injections or additional wells to treat or intercept the plume) but that such measures carry cost and no guaranteed rapid result. He and other staff recommended continuing the monitoring program, adding targeted monitoring wells down-gradient if a willing property owner is found, and considering mitigation only if the trend stalls or reverses.

On landfill gas, ARM Group reported recent elevated readings at two gas probes (GP-3 and GP-4) that the firm addressed by installing vent wells in a sand layer that had been permitting gas movement; Hundley said the vent wells have stopped gas readings at those probes. He also advised the board that post-closure-use guidance from DEQ favors ballasted (non-penetrating) systems for solar installations on closed landfills to avoid creating preferential pathways through the cap.

County staff and ARM Group emphasized process constraints: DEQ regulation requires a site be under the groundwater protection standard for three consecutive years before monitoring may cease, and weather conditions (including drought) can affect sample collection. Staff said that additional off-site monitoring wells — if owners agree — would improve the data the county can present to DEQ when seeking to end monitoring.

Board members and members of the public raised the trade-offs between potential revenue from a solar lease and long-term site safety. Some supervisors said they were reluctant to authorize construction activity that could disturb the cap while contamination persists; others said they wanted more technical detail on remediation timelines and costs before making a policy decision.

The board did not take a formal vote on the project during the meeting. Staff said they would continue sampling, share the June and subsequent results when available, and consider targeted additional monitoring if property owners permit wells to be installed.