Trihydro’s Ben McAlexander, together with colleagues N. Sihota, M. Lyverse, and K.U. Mayer, were recently published in the December 2018 Journal of Contaminant Hydrology for their article, “Multi-year CO₂ efflux measurements for assessing natural source zone depletion at a large hydrocarbon-impacted site.” The article shares an analysis of five years of hydrocarbon mass loss data from a large former refinery. The results demonstrate that surface CO₂ efflux measurements can be an indicator of underlying contaminant distribution (for early site screening) and that natural biodegradation can be an important component of site remediation.

Abstract excerpt
As the operational lifetime of many refineries exceeds 100 years, historical releases of oil and refined products is common. To evaluate remediation and rehabilitation options, there is a need to understand the rate and distribution of natural hydrocarbon mass losses across these large properties. Surficial CO₂ flux measurements were used to evaluate naturally occurring hydrocarbon mass losses at a large-scale former refinery that has been closed since 1982. Overall, mass loss rates calculated from CO₂ fluxes indicate natural source zone depletion (NSZD) can result in substantial contaminant removal, which may rival that obtained from engineered remediation systems, under some conditions.

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For questions about NSZD or hydrocarbon-impacted sites, contact:
Ben McAlexander, PG, H-GW
Hydrogeologist
307-745-7474
[email protected]