EARTHWORKS

Assessment of Groundwater Sampling Results Completed by the USGS

Assessment of Groundwater Sampling Results Completed by the USGS
Technical memo analyzing whether US Geological Survey sampling validates EPA investigation into Pavillion groundwater pollution by fracking

Published: September 30, 2012

By: Tom Myers PhD for Earthworks, Sierra Club, Natural Resources Defense Council

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From the report:

The organic chemistry at MW01 has not changed substantially since the EPA sampled the well; some constituents have increased and some have decreased, as would be expected with organic contaminants discharging from a series of event, the hydraulic fracturing of natural gas wells. Because the water chemistry data at MW01 has essentially been replicated, the evidence supporting the hypothesis that natural gas drilling activities, including fracking, have contaminated the Wind River aquifer near Pavillion WY has been strengthened. The conclusions based on that analysis should be more widely accepted now that the water quality has been replicated.

The concentrations of gas, including methane and ethane, have increased and that of propane has remained relatively constant. The ratio of ethane and propane to methane and the isotopic signature of methane all indicate that the gas source is thermogenic, meaning a deep formation. An increasing concentration indicates the formation is likely the source because the concentration will increase as more of the formation contributes to gas at the monitoring well.

EPA monitoring well 2 was not sampled because it did not yield sufficient water. The EPA had been able to purge over a borehole’s volume of water, therefore they were clearly sampling formation water. There is no reason to consider that the current condition of MW02 negates the results of the EPA in 2011. The problems with MW02 however indicate other problems with the sampling of these wells. The USGS used standard purge techniques, not techniques designed to minimize losses of volatile organics to the atmosphere. Purging too fast or drawing the water level too low could cause the measurement to be biased too low.

The problems with MW02 however indicate other problems with the sampling of these wells. The USGS used standard purge techniques, not techniques designed to minimize losses of volatile organics to the atmosphere. Purging too fast or drawing the water level too low could cause the measurement to be biased too low.

Tagged with: wyoming, water pollution, usgs, pavillion, groundwater, fracking, epa, encana

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