Assessing Analytical Issues and Improving/Remediating those Issues for the Analysis for Dissolved Gases in Potable Water Supplies – An Overview of Collaborative Studies by Producers, Laboratories and Regulatory Stakeholders

Shale Oil and Gas
Oral Presentation

Prepared by D. Gratson1, R. Vitale2, S. Brower2, L. Work2
1 - Environmental Standards, PO Box 29432, Santa Fe, NM, 87592, United States
2 - Environmental Standards, , Valley Forge, PA,


Contact Information: [email protected]; 505-660-8521

ABSTRACT

Analysis of methane and other light hydrocarbon gases in water has become an increasing interest in recent years due to significant expansion of shale gas drilling. Methane in water is not currently regulated by the US EPA; however, several states have elected to regulate methane in potable groundwater.

There is currently one published consensus method (ASTM D8028-17), which has limited single-laboratory study data, available to guide the analysis techniques for commercial and governmental laboratories. For a variety of reasons, this standard is rarely used by commercial laboratories and is limited as it has not undergone multi-laboratory validation. An unpublished, US EPA standard operating procedure (SOP) known as RSK SOP-175 has been in use for many years, along with notable number of variations developed by the commercial laboratory community.

The presentation will provide an overview of the collaborative study involving laboratory, government, and consulting that was sponsored by the oil and gas industries’ Marcellus Shale Coalition (MSC). Environmental Standards, Inc., designed the multi-laboratory study that included over 20 accredited laboratories (including one regulatory laboratory). The MSC study was performed over a 6-year period and documented significant method issues, diagnosed/addressed/remediated those issues and standardized a multi-laboratory validated method for the analysis for dissolved gas. The sponsors and stakeholders undertook this effort to assure that a multi-laboratory validated method for potable water sources, with known accuracy and precision, would be available to the accredited laboratory community to appropriately protect public health.
The presentation will describe the six phases of the collaborative study, highlighting the second interlaboratory study in 2021 using groundwater standards. During the initial study phases, significant precision and accuracy problems with measuring methane and other light gases were identified. The analytical techniques which demonstrated wide variability and low bias were identified within an alarming number of participating laboratories. Additional information collected during the subsequent phases of the study resulted in notable improvements in precision and accuracy across all participating laboratories. The lessons learned were applied in the preparation of a light gas analytical method that was recently used in two rigorous inter-laboratory studies. During a final phase of the study, the analytical method will be subject to an additional inter-laboratory study using real-world, spiked groundwater and a commercially available light gas certified reference material. A federal laboratory will be included in this final study phase as the US EPA is currently evaluating the method for inclusion in their SW-846 methods manual.