Thursday, May 10, 2012

Fracking and Groundwater We Still Don’t Know

A study based on a computer model was created by Tom Myers, PhD, commissioned by the Catskill Mountainkeeper a Youngsville, NY Environmental group and The Park Foundation in Ithaca, NY and recently released. The model was commissioned after the NY New York Department of Environmental Conservation’s (NY DEC) initial finding in 2009 that hydraulic fracturing could not impact groundwater. The NY DEC went on to commission an environmental impact statement (EIS) on drilling that was released for public comment in September 2011. The EIS recommends that drilling be permitted, but with conditions. The comment period for the EIS closed on January 11, 2012 and the DEC is now developing regulations.

Dr. Myers’ model is being submitted too late to be part of the public comment period, and the model did not use sampling or case histories to build the relationships that project  contamination risks. Rather, Dr. Myers, a PhD in hydrology and a consultant in Reno, NV; built a computer model designed to predict how fracking fluids would move over time. I have not seen the model and do not know how simulations account for the natural fractures and faults in the underground rock formations and fluid flow in the underground, the permeability and stress dependent permeability, and fracture porosity changes. The model simulations have not been tested in field studies.

The Myers model predicts that fracking will dramatically speed up the movement of chemicals injected into the ground. Fluids in his simulation traveled distances within 100 years that would take tens of thousands of years under natural conditions. When the model factored in the Marcellus’ natural faults and fractures and an assumed shale permeability, fluids could move into an aquifer region an order of magnitude faster than that- in as little as three years. Terry Engelder, PhD geology at Pennsylvania State University an expert on the Marcellus Shale and considered by some to be an advocate for hydraulic fracturing has reviewed the model. In a recent interview Dr. Engelder questions the permeability of rock that Dr. Myers assumed in his model. I do not feel I am qualified to judge this work.  

Dr. Myers work is in conflict with other studies done on the topic, but that does not prove him wrong, only actual field studies over a number of years can actually prove him right or wrong. At present there is little or no evidence of groundwater contamination from hydraulic fracturing of shale at normal depths. In Pavillion, Wyoming, were groundwater has been contaminated they used hydro fracking within the water table near drinking water wells. EPA initially announced that the glycols, alcohols, methane and benzene found in a test well the EPA drilled to the drinking water aquifer in Wyoming were likely due to fracking and then back peddled on that stating now the results were inconclusive and is performing additional testing. In an interesting coincidence or not, NRDC, the Wyoming Outdoor Council, Sierra Club and the Oil and Gas Accountability Project commissioned the same Tom Myers to review EPA’s draft report and Dr. Myers found “… the evidence presented in the EPA report …it is clear that hydraulic fracturing … has caused pollution of the Wind River formation and aquifer.” I did not find the evidence quite as compelling and agreed with the EPA that additional testing needs to be done. Dr. Myers continues with: “Three factors combine to make Pavillion-area aquifers especially vulnerable to vertical contaminant transport from the gas production zone or the gas wells – the geology, the well design, and the well construction.” True.

Dr. Myers current study deals with the Marcellus Shale. The model appears to assume that fluid migration will be away from the well. According to a research summary at the University of Texas at Austin, in the long term after fracturing is completed, the fluid flow is toward (not away from) the well as gas enters the well bore during production. Some with concerns about fracking allege while there may be a relatively small risk to water supplies from any individual hydraulic fracturing, a large number of wells within a formation like the Marcellus shale has a higher likelihood of negative impacts. However, the impact on a shale formation of a group of fracturing wells has not been studied. Fracking has outpaced our knowledge of the consequences.

In hydraulicfracking on average 2-5 million gallons of chemicals (< 1%), propping agent(<4.5%)  and water (>94.5%) are pumped into the shale formation at 9,000 pounds per square inch and literally cracks the shale or breaks open existing cracks and allows the trapped naturalgas to flow. After hydraulic fracturing a shale gas well, the fluid pressure is relieved and a portion of the injected fluid returns to the well bore as "flowback" water to the surface for treatment, recycling, and/or disposal. The amount of injected fluid returned as flowback ranges widely from 20% to 80%  due to factors that are not well understood by scientists, regulators or industry. It is not known whether the fracking fluids are absorbed into shale formation or instead migrate.  The route of escape may be through propagation of the induced fractures out of the target zone and into the aquifers, or intersection of induced fractures with natural fracture zones that lead toaquifers. The fracking fluid does not just disappear. No evidence of chemicals from hydraulic fracturing fluid has been found in aquifers as a result of fracturing operations, but impacts of hydraulic fracturing on groundwater have not been carefully monitored over a period of years.

 It is essential to determine the vertical and horizontal separation that is necessary to protect the drinking water aquifers from fracking and what impact new rounds of hydraulic fracturing can have on previous developed areas with old abandoned wells or currently producing wells before watersheds are damaged or destroyed. Building dueling computer models based variously on Hookes’ Law, and Darcy’s law or classical theory is not the way to determine this. The fate of the unrecovered fracking fluid needs to be found. It is believed by many geologists and engineers that the intervening layers of rock would prevent a fissure from extending thousands of feet to the water table this assumption needs to be tested in the real world, and the long term impact of fracking, deep well injection and fluid disposal has on watersheds needs to be studied and monitored and a safe separation distances from aquifers need to be determined. Then increased oversight needs to be implemented to ensure that this separation is maintained (despite inevitable requests for waivers), improve well-design requirements and ensure their consistent implementation and require the appropriate treatment and recycling of drilling waste water. Use of waste water treatment plants that were designed to address biological solids to treat millions of gallons of water used for hydraulic fracturing or ponding the waste is short sighted and imprudent. The deep well injection commonly used in Texas may have consequences beyond small earthquakes. 

Right now there is an excess of natural gas and the price is still well below $3 per million BTU which is the estimated cost of shale gas from fracked wells in the Marcellus Shale. This is a great time to intensely study the environmental impacts from fracking- when we aren’t desperate for the natural gas and EPA has just released a set of air release rules and draft water permitting rules addressing fracking and is about to release a set of regulations for fracking on Federal land. The Department of the Interior estimates that over 3,000 wells are fracked on Federal and Tribal land each year. Sounds like a good number of test sites. Though it would help to baseline the water quality (or at least reduce the costs for analysis) to know the chemicals used in the hydraulic fracking water before not after the frack. However, since long term monitoring is needed it should not make much of a difference in analytical costs. 

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