In the town's statement it mentions the following.
The 1.8 PPM “normal background level” of methane referenced in the article is not an established limit included in any of the previous studies conducted by the Texas Commission on Environmental Quality (TCEQ).
The TCEQ may not have an established limit but the EPA Measurement of Fugitive Emissions at Region 1 Landfill states that the global background methane concentration level is 1.75 ppm.
In the below paragraph from the town's response it mentions how methane can be emitted from other natural and man made sources.
The primary component of natural gas, Methane is a non-toxic compound emitted from natural and manmade sources including wastewater treatment plants, livestock operations, mobile combustion, landfills, and natural gas and fossil fuel production operations. Methane can displace oxygen, resulting in an oxygen-deficient environment in confined areas, but because it is lighter than air, Methane tends to rise in open environments.
In this EPA Chemical Descriptions, this talks about other sources of methane and typical levels ppm. The levels detected the other night here in Flower Mound were much higher than the levels listed below.
Typically levels are below 1 ppm, except near landfills and some wetlands. Along the perimeter of the ConocoPhillips-Rodeo refinery, levels at the north fenceline are usually slightly higher than at the south fenceline, but levels are usually below 2 ppm.
The paragraph below is an indication that someone is not being truthful.
The agency also fielded several calls regarding the story, but indicated the complainants stated that they were not smelling any gas or noticing any problems.
We know for a fact that the first complaint made Wednesday evening, was made because of odor. Indicating that some other chemical was present. Also, we have received e-mails from two other residents that complained to the TCEQ of odor. Methane does not have an odor but in recent tests in Dish, many toxins can accompany methane and they have odor and cause health problems. In fact, this post from txsharon talks about the Dish study and the recent methane mapping in Flower Mound.
In DISH when these chemicals were detected, the methane was 3 times the normal level at 5.9ppm. The methane in Flower Mound exceeded 40ppm on March 2nd and March 3rd. That's 6.7 times more methane than what was found in DISH.The methane is a concern not because it is toxic but because it is a potent greenhouse gas and the fact that methane is escaping means it is likely that other chemicals are also present.
There have been canister samples taken by the TCEQ, we will have to wait to see what the results are. We can only hope that the same thing that happened with the Town's "baseline" results does not happen with these air quality results. Rumor has it there were elevated levels of carbon disulfide in these tests. It appears a certain gas drilling company may have got a hold of them before the town did.