Resolving The Irresolvable Through Data Integration For The Transmitter Site, Bucks Harbor Me

The Transmitter Site is one of three formerly used defense sites in coastal Machiasport ME, located on glacial sediments underlain by Devonian igneous rocks. Integrating all available surface and borehole geophysics, hydrogeologic and historical site data in three dimensions produced a defensible Transmitter site conceptual site model meeting many of the requirements for a Technical Impracticability (TI) and TI Zone at a fractured rock site where the task was not thought possible. A perchloroethylene (PCE)/trichloroethylene source area is within the current Cold War era septic system, leaching transformed contaminants (trichloroethylene) into the underlying glacial sediments, and fractured bedrock. The septic system overlies a north-northeast/south southwest fracture zone or pathway potentially contaminating groundwater used by homes built on Yoho Head Road since 1996. A second shallow valley or bedrock trough following the west-southwest transmissive fracture trend may also be potentially contaminating groundwater used by homes built on Yoho Head Road since 2009. The defensible, data based three dimensional conceptual site model identifies several residential well monitoring data gaps, and meets many of the TI Waiver and TI Zone requirements. The TI waiver is a more feasible site closeout option when visualizing the data in the context of the site’s current conditions and path forward. Removing the shallow PCE-TCE contaminated soil follows the TI Waiver practice at many sites with contaminated fractured bedrock aquifers. The model allows for quick TI zone determination, key requirements for a TI Waiver, especially when done after the soil removal. Adding domestic wells potentially located along the newly identified fracture zone trends improves public health protection, verifies site contaminants are not reaching these homes, and establishes the basis to take appropriate actions if TCE is found.