Formatted Title
Striving for More Sustainable Risk Management at Petroleum Contamination Sites
Background/Objectives
The scarcity and over-withdrawal of groundwater to meet societal needs has placed a premium on sustainability and preserving usable groundwater for future generations. This stewardship has served as a driver for groundwater remediation at many petroleum hydrocarbon sites. Although certain engineered remediation systems can help meet this goal through hydrocarbon mass removal, the benefits come at a sacrifice to atmospheric resources through global warming and carbon dioxide (CO2) emissions. Fortunately, our planet’s aquifer systems are equipped with a natural assimilative capacity in the form of microbes that can achieve greater hydrocarbon mass removal without corresponding detriment to global warming. Hence, understanding the role of mother nature and, in particular, rates of natural attenuation are critical in optimizing the implementation of engineered remediation to achieve a net environmental benefit.
Approach/Activities
Rates of hydrocarbon mass removal in source areas where light non-aqueous phase liquid is present (i.e., natural source-zone depletion [NSZD]) can exceed rates of certain poorly performing active/engineered remediation systems. Although guidance on NSZD and different methodologies for rate quantification have been available for more than a decade, the science on NSZD has evolved, including new tools for quantification and new approaches that more strategically target site risk.
Results/Lessons Learned
The goal of this presentation will be to present recent and developing American Society of Testing and Material (ASTM) and industry guidance on NSZD that highlight various measurement methods and ways to effectively incorporate NSZD in remedial decision making. Equipped with this knowledge, regulators, industry, and remediation practitioners can make more informed risk-management decisions that benefit both groundwater and atmospheric resources and help preserve the planet for future generations.