The state Department of Environmental Protection is trying to learn how methane gas ended up in residential drinking water wells in Moreland and Franklin townships near Lairdsville in eastern Lycoming County, the agency confirmed Wednesday.
The agency also learned of bubbling in Little Muncy Creek. That situation was investigated and it was determined the bubbling, which occurred along a 50-yard section of the creek, was caused by methane.
DEP spokesman Daniel Spadoni said methane has been found in five water wells. Test results showed methane levels were "elevated" in two of the wells while test results of the other three are pending.
"We initially received a complaint about bubbling in a private drinking water well on May 17," Spadoni said. "We did find elevated levels of methane in the head space of that well."
XTO Energy, a division of ExxonMobil, has a well pad with three drilled and hydrofractured natural gas wells on it within about 2,300 feet of the first well it investigated, Spadoni said.
The agency received a report about the bubbling in the creek on June 9, he said.
Spadoni said the DEP has no knowledge of methane impacting aquatic life in the creek.
DEP is investigating the situation, Spadoni said. So far, no methane has been found in any of the homes where the water wells are located, he said.
"We have an ongoing investigation and have not made any determination as to the source or sources of the methane," he said. "The investigation is complex and will take time to resolve."
Asked if any of the water wells had been tested prior to the gas wells being drilled, Spadoni said, "there is some pre-drill data available. We have requested that information as part of our investigation."
Spadoni said XTO has launched its own investigation and is cooperating fully with DEP.
The company voluntarily has ceased operations in the county, has provided the five water well owners with potable water, has vented the wells with 6-inch PVC pipe to prevent the buildup of gas and is doing daily residential well screening of other nearby wells.
Spadoni said his agency's investigation includes isotopic testing to determine the chemical footprint of the methane in the wells.
"That allows us to determine whether it is thermogenic or biogenic (gas)," he said. "Biogenic would be like swamp gas, related to the natural decomposition of matter. Thermogenic would be predominantly from a shale formation."
XTO spokesman Jeffrey W. Neu said the company is working "hand-in-hand" with DEP.
"We are doing everything we can in conjunction with them," he said. "We want to make sure we know what's going on so we can operate out there and continue to do it safely."
Neu said water samples collected by the company in the area prior to drilling revealed the presence of methane.
"We looked at residential wells within 4,000 feet of certain Lycoming County wells sites. Pre-drilling water samples indicated the presence of gas prior to the commencement of drilling in that area," Neu said. "In general, the gas levels that were detected after drilling was completed were similar to the pre-drilling samples we studied."
Neu said he was unsure as to whether water wells near the Moser site had been sampled.
He said his company's assistance to well owners is not an admission the company caused the methane in the water.
"When we do this we're not saying we're responsible," he said. "We're doing this as good corporate neighbors."
Spadoni said methane in water wells can be dangerous.
"If the (methane) level is too high and there is some ignition source, there could be an explosion," he said.
"Water that has methane in it is not toxic to drink, but obviously it has an explosive nature to it, particularly in confined spaces," said Thomas Murphy, co-director of the Marcellus Center for Outreach and Research.
According to information provided by DEP, methane is an odorless, colorless gas that can accumulate in water wells that have not been properly ventilated. Methane also may migrate into basements of homes and structures containing electrical connections, creating an explosion hazard.
According to Murphy, there are a large number of private water wells throughout the northern tier of the state with low levels of naturally occurring methane.
Prior to this year, there were issues involving the migration of methane into water wells as a result of gas drilling operations.
Since the state implemented more stringent gas well casing standards on Feb. 5, the number of incidences involving drilling-related gas migration has dropped significantly, he said.
"To date, they haven't found any Marcellus methane gas in ground water or drinking water wells," Murphy said. "It's the gas from the upper zones that has found it way into (ground water or drinking water wells) due to poor well casing and cementing."