Under a project sponsored by the Department of Defense ESTCP program a group of scientists from NAVFAC, USGS, PNNL and Subsurface Insights demonstrated the feasibility of monitoring amendment emplacement and subsequent behaviour. This project ( ER-0717: Optimized Enhanced Bioremediation through 4D Geophysical Monitoring and Autonomous Data Collection, Processing and Analysis) took place between 2008 and 2010.
The demonstration was designed to field validate the feasibility of monitoring amendment injection and subsequent behaviour through automated electrical geophysical resistivity acquisition, processing and result delivery. This was done by deploying an electrical geophysical borehole and surface array as well as an associated sampling well array at the Brandywine DRMO in Brandywine, Maryland over an area where enhanced bioremediation was being conducted and collecting and processing timelapse electrical geophysical data.
During the demonstration three separate amendment injection events were monitored. The primary demonstration (which occurred from March 2008 through July 2010) involved the long term monitoring of a lactate based amendment which was injected as part of a site wide enhanced bioremediation effort. Two secondary demonstrations (done as part of a project extension) used the injection of molasses in August 2010 to demonstrate real time performance of the system. The first injection event and subsequent long term monitoring conclusively showed the ability of the monitoring to observe the initial emplacement and spatial distribution of the amendment as well as subsequent groundwater flow induced amendment dispersion. It also showed the sensitivity of the geophysical monitoring to processes associated with enhanced biological activity. The objective of the molasses injections was to demonstrate the real time capability. This was confirmed by project members, DoD and DOE staff who (both in the field and from remote locations) were able to observe the injection signature through a web interface within 1 hour of amendment injection.