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Wright County supervisors debate seismic testing setbacks, monitoring and liability
Summary
County engineers and supervisors discussed proposals from Twin Rivers Exploration to use closer setbacks with live monitoring for seismic testing; supervisors expressed concern about liability to the county and favored maintaining a 250-foot setback in the county road use agreement.
Wright County supervisors and county engineers discussed whether to alter the countys road use agreement that governs seismic testing on county roads and rights-of-way. Twin Rivers Exploration asked for relaxed setback rules in combination with continuous monitoring, but county officials raised concerns about risk and long-term liability.
County engineering staff presented a risk analysis prepared by an independent engineering firm (Allender/Budeke) that used peak particle velocity (PPV) thresholds to model the chance of tile or structure damage from seismic testing. The engineers reported a PPV threshold of 0.5 (units: peak particle velocity) as a point where risk of deformation rises if testing occurs within 50 feet of a subsurface tile or structure. The county currently has a 250-foot setback in its road use agreement.
Twin Rivers Exploration representatives proposed "walk-along" monitoring: a technician on site continuously monitoring PPV and stopping operations if readings approach the 0.5 threshold. County staff acknowledged the companys offer but outlined concerns about whether the county should accept the liability and monitoring burden on its public roads.
Several supervisors said the county should not assume extra risk for private exploration. One supervisor said, "I don't see why the county should take on that risk. . . If you can't do it with that, then go talk to the landowner and proceed that way." County staff added the existing agreement includes a 10-year callback provision to recover county costs if testing causes damage.
County engineers reported other county engineers in the region were also uncomfortable with reducing setbacks and had similar liability concerns. The county will communicate its position to Twin Rivers Exploration and indicated it will require either compliance with the current 250-foot setback or direct agreements with private landowners for closer testing.
Why this matters: seismic testing can be a preliminary step toward resource development; supervisors balanced potential long-term economic benefits against the risk of damage to drainage tile and county infrastructure and the difficulty of enforcing continuous monitoring on public roads.
