All ground water contains methane. It is very easy for methane, which flows easily through rock, to percolate through layers of strata.
To contend that gas is resulting from well frac of the Marcellus is absurb.
In the case of this part of the Marcellus, heavier components are present that should also show up in groundwater if its origin was there.
Looks like a shakedown attempt.
And I understand some do have separators to extract methane, if enough is present.
That shakedown technique is part of the leftist playbook and has been sued in several applications over the years. Before the methane in wells thing in PA, it was used to shakedown Exelon nuclear over supposed groundwater contamination with tritium. By the time the late 1990's rolled around, chemical detection technology had progressed to being able to easily detect parts per trillion, and a routine test of groundwater around the Braidwood plant detected tritium for the first time, and even though it was orders of magnitude lower than EPA limits, a panic was started by anti-nuke groups that Exelon was at fault. Never mind that the wells in question were sandpoint wells created by driving a 20-30 ft long perforated steel pipe into the sandy soil to access the very shallow water table left after all the local swamps were drained, and this water was heavily contaminated with fertilizers, herbicides, pesticides, and human/pig/cow/chicken fecal matter, folks were panicked into blaming the tritium and Exelon.
Exelon tried fighting it with facts, but to no avail. The dhimmicraps who controlled the Illinois government got on the bandwagon early and kept hammering them. They finally gave in and gave millions of dollars to finance new water systems for these folks and the developers who were developing new housing tracts near the Braidwood and Dresden plants. It did not help that they later found leaking underground pipes that carried tritiated water at the plants, even though this was not the source of most of the tritium detected in the sandpoint wells. The lawyers and antinuke groups got most of the money, but the locals did get new municipal water systems to replace the sandpopint wells.