Oil and Gas at Your Door? (2005 Edition) - Earthworks

IMPACTS ASSOCIATED WITH OIL AND GAS
Water Quantity
Every minute, a CBM well may pump as much as 15 gallons of produced water. 288 This may lead
to significant drawdown of local and regional aquifers and reduction of ground and surface
water supplies. As mentioned in the chapter on Coalbed Methane, some aquifers in coalbed
methane producing areas have fallen by 200 feet or more. 289 The BLM estimates that groundwater
levels in the Powder River Basin will drop by 600 to 800 feet, if that region develops their
CBM resources at the BLM’s intended rate. 290
If regional groundwater levels become too depleted, local springs, streams, domestic and stock
water wells, and subirrigated acreages will be affected. 291 Significant reduction in these waters
would be harmful or fatal to aquatic life and wildlife; crop production could decrease; and carrying
capacities and distribution patterns for livestock and wildlife could be significantly and
adversely affected. 292 This could have a devastating impact on local/regional ecosystems and
economies dependent on them.
Dewatering of Coal Beds
Coal will not burn as long as it is saturated with water. But when coal beds are dewatered, and
especially if they are close to the surface, the coal may catch on fire from lightning strikes, wildfires
and spontaneous combustion. This is a potential concern to landowners because once
underground coal fires begin to burn, they are almost impossible to put out; the burning coal
releases carbon monoxide; and the layers of rock and soil above the coal can collapse as the
coal continues to burn. 293 Carbon monoxide can lead to fatigue in healthy people, chest pain in
people with heart disease, and at higher concentrations, it can cause impaired vision and coordination;
headaches; dizziness; confusion; or nausea.
Methane and Hydrogen Sulfide Migration
Massive dewatering of aquifers may also lead to increased methane or hydrogen sulfide (H 2 S)
migration to the surface. In some areas, dewatering (which releases methane from the coal),
and the structure and layering of the geology create pathways that allow these gases to flow to
the surface. 294 The escape of methane or H 2 S can also result from inadequate well control procedures
and faulty casing or plugging. 295 The gas can then collect in explosive levels in homes.
Methane and H 2 S seepage/venting may be one of the most disastrous problems facing
landowners living in close proximity to CBM operations. 296
EPA spoke with a former county employee, who worked for Exxon performing hydraulic
fracturing jobs in an earlier career. As a county employee, he took measurements for
methane and hydrogen sulfide inside homes in response to citizen complaints.
According to his information, there were not significant problems until the shallowest
formation, the Fruitland coal, began being developed. He believes that the main route
of contamination is from older, poorly cemented wells. The county official
estimated that hundreds of wells have been impacted. He said the
biggest problem associated with the apparent effects of CBM development
is explosive levels of methane and toxic levels of hydrogen sulfide
in homes. In his opinion, this is due to removal of water rather than
hydraulic fracturing. — Excerpt from EPA’s DRAFT Evaluation of Impacts to
Underground Sources of Drinking Water by Hydraulic Fracturing of Coalbed Methane
Reservoirs. 297
Disposal of Produced Water
The United States produces 20 to 30 billion barrels of produced water every
year. 298 Prior to the enactment of environmental regulations in the 1970s,
produced water was disposed of using the most economical method. This
often resulted in the intentional discharge of the water on the ground surface.
299 Today, the most common methods of disposal are injecting it into the
FIGURE I-34. HYDROGEN SULFIDE WARNING
Hydrogen sulfide may be associated with produced water.
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