The Data Don’t Lie: Has MNA Science Outpaced Site Decision-Making?

Posted on July 26, 2016 by Charles Efflandt

The importance of a thorough technical evaluation of monitored natural attenuation (MNA) at chlorinated solvent and other groundwater-contamination sites cannot be overestimated. Regulatory acceptance of MNA as a preferred remedial alternative can save millions of dollars in response costs compared to common presumptive remedies. Because “active” remediation technologies rarely achieve complete contaminant treatment or removal, MNA is an implicit, if not specifically evaluated, component of most groundwater remedial actions. A proposal to use MNA as the primary cleanup mechanism, however, is often met with resistance from regulators, notwithstanding years of supportive data.  Such resistance may be attributable to antiquated agency policies or, perhaps, an inadequate evaluation of evolving MNA science.

The use of MNA at groundwater sites has typically required a showing of a stable or shrinking plume, source control, sustainable natural attenuation conditions, and acceptable risk to health and the environment. Today, mathematical and modeling tools can systematically establish data trends demonstrating that remedial action objectives will be achieved through natural attenuation in a reasonable time frame.

Unfortunately, even if confronted with irrefutable data, many state regulators will reject meaningful consideration of MNA unless the attenuation mechanism can be pigeon-holed into  policies that focus on the demonstration and scoring of anaerobic biodegradation conditions at a site.  That is because after almost two decades, EPA’s 1998 Technical Protocol for Evaluating Natural Attenuation of Chlorinated Solvents in Ground Water remains the framework for MNA evaluations and decision-making in many states. Because the 1998 Protocol presumed that the primary effective mechanism for natural attenuation was anaerobic biodegradation, the Protocol has unduly restricted state policies for screening and approval of MNA remedial action.

Numerous studies since the publication of  the 1998 Protocol, however,  have shown that a viable MNA remedial strategy can be supported by attenuation mechanisms other than anaerobic biodegradation These studies have documented other viable contaminant-destructive attenuation mechanisms and evaluation tools, such as aerobic cometabolism enzyme degradation, magnetic susceptibility, compound specific isotope analysis, and improved sampling and modeling techniques. Greater awareness of these scientific developments by regulators and environmental professionals will result in MNA being an increasingly important remedial tool at many groundwater sites.

We have learned the hard way that it’s much more difficult and expensive to clean up sites using default remedies than first thought. Fortunately, it is becoming increasingly apparent that nature has an ability to degrade various chemicals more quickly and effectively than previously believed.   Regulatory acceptance should not, and need not, include unreasonable technical hurdles, such as imposing  attenuation “causation” requirements that are neither feasible nor necessary to support what cannot be disputed. That a proposed MNA remedy does not neatly fit into the traditional anaerobic degradation box, and cannot with precision be attributed to one or more alternative degradation mechanisms potentially active at a site should not be determinative. At the end of the day, the data don’t lie. The MNA determination ought to begin with, and remain focused on, the empirical data and data trends.

Shoot First -- Ask Questions Later

Posted on September 26, 2013 by Mark Walker

“Shoot first, ask questions later” is how Congressman Chris Stewart described EPA’s efforts to link groundwater contamination to hydraulic fracturing.  Stewart is the Chair of the Environmental Subcommittee of the House Committee on Science, Space and Technology, chairing the July 24 hearing on “Lessons Learned:  EPA’s Investigations of Hydraulic Fracturing.”  Specifically at issue was the EPA’s investigation in Pavillion, Wyoming.

In December, 2011, the EPA issued a “draft” report which concluded that hydraulic fracturing in the Pavillion, Wyoming gas field had caused pollution of the deep drinking water aquifer.  The draft report was based upon sample results from two EPA monitor wells and was issued without peer review or stakeholder input.

There were serious flaws with EPA’s work.  For starters, EPA failed to complete the monitor wells according to its own guidelines.  Annular sealants were not properly installed, allowing cement to impact the water quality.  A landowner’s complaint that EPA had an anti-freeze leak during drilling operations was not disclosed in the draft report.  EPA exposed the wellbores to painted low-carbon steel casing and welding materials, which are known to contain various organic and metal compounds, yet the report inaccurately stated that stainless steel casing had been used.  Moreover, several of the constituents which the EPA attributed to hydraulic fracturing fluids (e.g. glycols, 2-butoxyethanol and phenols) are known to be associated with the high pH cement that the EPA used to complete the wells.  The bottom line is that the EPA’s own operations introduced the contaminants that it blamed on hydraulic fracturing fluids.

Subsequent testing by the USGS was unable to verify the EPA’s results.  The USGS was unable to find some of the compounds that EPA claimed were present, and other constituents were found at significantly lower levels.  The USGS was unable to sample one of the two wells due to improper well construction.

The EPA has now walked away from its flawed study, turning the entire investigation over to the State of Wyoming.  The EPA has stated that the draft report will not be peer reviewed or finalized, and that the results will not be used in its national hydraulic fracturing study.  Nevertheless, the EPA’s handling of Pavillion has cast doubt over the EPA’s national investigation of hydraulic fracturing intended to develop regulatory policy for unconventional reserves, causing Chairman Stewart to conclude, “given EPA’s rush to judgment in Wyoming…we should question whether the Agency’s ongoing study is a genuine, fact-finding, scientific exercise, or a witch-hunt to find a pretext to regulate.”