Alexander, M. | Remediation 30(2): 25-35(2020)

In situ bioremediation was selected to remediate a 29-acre dilute, acidic and aerobic, chlorinated solvent plume (mainly TCE and 1,1-DCE) at the Monitor Devices Inc./Intercircuits Inc. Superfund site in New Jersey. Full-scale implementation of the reductive dechlorination and bioaugmentation began in late 2010, and treatment continued steadily over 9 years. The amendments injected included electron donor and bicarbonate buffer solution and, once anaerobic aquifer conditions became established, a bioaugmentation culture. Amendments were injected in multilevel injection wells (IWs), to maintain control over the vertical interval of amendment delivery. The areal coverage of the plume has been reduced by 59% based on the 10 µg/L TCE isocontour and the contaminant mass has been reduced by 79%. Lessons learned from this project include the need for bioaugmentation in the acidic aquifer and an efficient and effective manner of well construction and amendment injection using multiscreen single casing IWs and packer systems. Also, there were differences in longevity of the electron donor amendment versus the bicarbonate neutralization additive, and varied amendment delivery techniques (IWs, direct injection, horizontal well installation) were needed in selected lower permeable zones to attain treatment.