Andrew J. Kirkman P.E.,
Group Subject Matter Expert Petroleum Remediation
Andrew Kirkman is a hydrocarbon and hydrogeology subject matter expert for BP. His experience includes LNAPL at hydrocarbon sites and DNAPL related to coal tar and creosote. Andrew's career started doing field work including groundwater sampling, well installation, and hydrocarbon field investigations at railroad, pipeline, manufactured gas plant, and tie treatment plant sites. Continual technical development resulted in Andrew leading the AECOM’s LNAPL technical practice, leading the development of the ASTM LNAPL Transmissivity standard prior to joining BP. Andrew has publications in peer reviewed journals and technical guidance documents including a recent publication on NAPL drawdown in fractured settings published in Groundwater Monitoring and Remediation in 2020. In his current role, he has continued to provide workshop conference presentations and webinar trainings. Andrew was previously a trainer for ASTM International on the LNAPL Transmissivity Standard E2856-13, has been an ITRC LNAPL trainer for the past 7 years, as well as provided LNAPL related training for the States of Virginia, Colorado, Missouri and Minnesota.
Compositional Effects from Natural Source Zone Depletion at Site with a Light End Crude Oil Spill
Andrew Kirkman, PE (BP Remediation Management, Naperville, IL).
Background/Objectives. Natural Source Zone Depletion represents the natural attenuation capacity of the subsurface to reduce LNAPL sources over time. Multiple methods have been developed to calculate the instantaneous rate of biodegradation but few have been able to directly identify the cumulative effect NSZD has induced.
Approach/Activities. Hydrocarbons released to the subsurface whether a crude oil or a refined gasoline are comprised of hundreds of compounds. Each of these compounds exhibits different partitioning behavior as well as substrate preference by microbes. This results in NSZD changing the composition of the LNAPL over time where it is possible to estimate the fraction lost as a function of a single compound as documented by CRC Care guidance. This discussion will provide the results of two dozen samples collected over 17 years at a crude oil release. The results will be related to the weathering behavior currently documented in literature as well as other NSZD related publications indicating NSZD as a plume stability mechanism.
Results/Lessons Learned. The resulting behavior model can be used to directly identify the cumulative compositional effect NSZD has achieved at various locations within the plume. A discussion of alternative methods to help quantify the confidence of these estimates will be provided. The intent is to provide improved guidance on analysis methods and consideration when applying the compositional NSZD based methodology in addition to highlighting the cumulative losses of LNAPL.