Thursday, June 30, 2011

Marcellus Shale Drilling: Concerns for Water Resources

by Dr. Susan Cushman, FLI Research Scientist; Director of Introductory Biology Laboratories, HWS Department of Biology

Drilling of the Marcellus Shale has the potential for serious environmental implications. Extending halfway up into the Finger Lakes region from the Appalachians and even into the Catskills, this Devonian age sediment was deposited by an ancient river delta, and includes a large amount of natural gas. It has been stated that the Marcellus Shale deposit holds 10-20 years of natural gas supply for the entire nation, yet process of extracting this resource from horizontally oriented fractures is significant to the surrounding terrestrial environment.

In particular, the processes of site analysis and clearing as well as gas production and delivery could have major impacts to both water quantity and quality within the area surrounding a well. There are four main concerns for water resources related to drilling the Marcellus Shale: 1) clearing land for well pads, 2) supplying water for well construction and drilling, 3) degradation of water quality in local streams due to increased traffic by large construction vehicles on rural roads, and 4) disposal of large amounts of waste “water”, e.g. contaminated fluids from wells. First, a well site must be completely cleared of trees and vegetation (5 acre pad = ~3500 trees), which means that rainwater will not be intercepted, and instead run overland polluting local streams with excessive amounts of sediment. Secondly, each of these drilling sites requires large amounts of water to keep the drilling bit cool. Water is also needed to create hydrofrack fluids enable both shale fractures to be held open under pressure and the gas to be released upwards through the well. The estimated water use of one well is 1.5 million gallons during drilling – 62.5 times more than a traditional vertical well. The increased traffic by heavy construction vehicles and tanker trucks that bring in this water will most likely increase the erosion along rural routes, thereby increasing sediment in small streams. Knowing that small streams lead to bigger streams and lakes in the Finger Lakes region, this could significantly impact our water quality. Finally, the wastewater that results from the hydrofrack creates significant concern over where to put it. Currently, the wastewater from hydrofracking systems is sent to wastewater treatment plants (PA) or sometimes injected back into the earth at a shallower depth (TX, WV). Wastewater treatment plants don’t necessarily have the ability to remove contaminants like brines, heavy metals, and radionuclides that are present in these contaminated fluids – and therefore pose concerns to our drinking water supplies if disposed of in this way. If injected back into the ground, there are also concerns over groundwater supply contamination unless it is injected well below known aquifers.
Source: Finger Lakes Institute Happenings

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