Natural attenuation of TCE and cis-DCE was previously observed at a fractured rock site in southern California, and was attributed to both biological and abiotic reactions (Darlington et. al. 2008, see project "Abiotic Natural Attenuation"). Enhanced bioremediation was to be evaluated as part of the feasibility study (FS). I reviewed the laboratory work carried out at Clemson University by graduate student Rong Yu in the lab of Dr. David Freedman. Preliminary results yielded a surprising finding; Dehalococcoides or equivalent microorganisms live in the pore spaces in the rock, as indicated by dechlorination of TCE to ethene with the addition of lactate in microcosms constructed from deep (900-1200') rock cores (Rong Yu et. al. 2018a). Microorganisms known to degrade acetylene anaerobically were also detected, indicating acetylene (an abiotic degradation product) could be removed as fast as it is produced. The 2nd phase of work used intact cores and showed the role of matrix diffusion at the site (Rong Yu et. al. 2018b). I reviewed the final report to the client. Don't be fooled by the man with his hands in the anaerobic glove box; grad student did all the work.
