The two reports released by the U.S. Geological Survey (USGS) Wednesday provide no evidence that hydraulic fracturing has created impacts to groundwater, an EnCana Corp. spokesperson told Rigzone Friday.
"Furthermore and more importantly, [Environmental Protection Agency] has provided no sound scientific evidence that drilling has impacted domestic drinking water wells in the area," said spokesperson Doug Hock in an email statement.
Hock said there was nothing surprising about the USGS results, noting that USGS did a credible job of sampling, said Hock.
"More importantly, however, is the fact that USGS only sampled one of the two EPA monitoring wells (MW). This goes to the heart of concerns raised previously by state and federal agencies as well as Encana," said Hock.
The USGS report seemed to indicate that the agency declined to sample MW02 because the well could not provide a sample that was representative of actual water quality conditions, Hock said.
EPA has said that the USGS results are "generally consistent" with their own prior sampling, Hock noted. However, Encana's comparison of EPA's sampling of MW01 with the USGS sampling of the same well provides "a good reality check" on this statement.
A comparison of EPA reported detections in EPA Well MW01 and USGS results show that the USGS results are inconsistent with the EPA results on the levels of toluene, xylenes, isopropanol, diethylene glycol, triethylene glycol, 2-Butoxyethanol and acetone. The USGS did not detect these in its tests.
For two components - potassium and DRO - the USGS results show significant decreases in concentrations versus the EPA results, according to a comparison by Encana of EPA and USGS data.
With regard to its claims related to hydraulic fracturing, EPA has contended that the elevated pH levels are due to potassium hydroxide, which is sometimes used in hydraulic fracturing. However, potassium hydroxide was not used in hydraulic fracturing jobs in the Pavilion field and would actually have been detrimental to the types of fracs done in the Pavilion, said Hock.
"The elevated pH is more logically explained by the fact that EPA used cement slurry in setting the casing of its monitoring wells and screens without the use of a bentonite plug to keep the cement from leaking into the well itself," said Hock.
The plus is required for monitoring well construction for USGS and the Wyoming Department of Environmental Quality.
"The slurry entering the well is also the reason that clean samples couldn't be obtained from MW02," said Hock.