Pennsylvania regulators say "improper" construction at Cabot Oil & Gas Corp. wells in northeastern Pennsylvania led to contamination at nearby private water wells.
The Pennsylvania Department of Environmental Protection (DEP) cited the Houston company for three violations in Susquehanna County last September, saying poor well construction caused methane to seep into groundwater and three private water wells.
The DEP is still investigating if a fourth private well may have also been impacted.
According to a notice of violation sent to Cabot, but not made public until the Scranton Times-Tribune began reporting on the issue this week, the DEP began investigating last August after residents in Lenox Township complained about methane being present in private water supplies located 1,400 feet from Cabot's three-well Stalter pad.
Methane levels in the water supplies jumped from 0.29 mg/L in a pre-drill sample collected on Nov. 11, 2010, to 49.2 mg/L on Aug. 16 and 57.6 mg/L on Aug. 18, according to the DEP. The DEP also found "combustible gas" in the headspace of the water well. Additionally, the DEP found natural gas present between various casing strings of the three natural gas wells at the Cabot pad, and later reviewed downhole video from one of the wells that revealed "improper" construction of one of the casing strings.
"The department is working with Cabot to determine appropriate remedial work at the Stalter wells. DEP will continue to closely monitor the situation," DEP spokesman Dan Spadoni told NGI's Shale Daily, adding that the investigation remains ongoing.
The DEP previously blamed Cabot for contaminating water wells serving 19 households in Dimock Township. The company continues to deny that charge, but through a settlement agreed to pay pay the affected residents $4.1 million, provide whole-house gas mitigation systems and make water deliveries (see Shale Daily, Dec. 17, 2010).
After first saying that local water was safe to drink, the U.S. Environmental Protection Agency (EPA) recently asked residents in Dimock to participate in a voluntary survey to address "potential gaps in sampling and sample results" (see Shale Daily, Jan. 3).