A hexavalent chromium (Cr[VI]) plume is present at a compressor station. I provided third party review for one of the stakeholders in evaluating enhanced biotreatment pilot tests and natural attenuation (NA) of the plume. The plume is headed toward a river but NA in the highly organic fluvial sediment deposits of the river is reducing Cr[VI] to Cr[III] prior to the plume discharging to the river. This could potentially eliminate the need for active treatment in the upland portion of the plume which will be both costly to the RP as well as disruptive to stakeholders.
However, enhanced bioremediation was chosen in the FS as the preferred remedy for both upland areas and the alluvial floodplain. The current task is to ensure bioremediation will be implemented in a manner that will be successful in the shortest amount of time, and with the lowest level of infrastructure installation and disruption for stakeholders.