Strategy For A/M Area Production Wells

Savannah River Site personnel are planning a two phase program in order to significantly reduce the amount of dissolved chlorinated solvents that are being transported to the McQueen branch Aquifer via the wellbore and gravel pack zones of the A/M Area production well system. In Phase I of the program a commercially available inflatable packer and check valve assembly will be installed inside the casing at the altitude of the McQueen Branch Confining Unit. This immediate, short term solution will eliminate the majority of the contaminant mass that is moving downward through the wellbore of the A/M Area production wells. During the packer installation process several pre- and post- testing activities are planned to aid SRS investigators in understanding the dynamics of the flow conditions and effectiveness of the installed assembly.The second phase of the program will address the small amount of contaminant mass that is moving downward through the continuous gravel pack of the production wells. The investigative data obtained during Phase I of this program will be beneficial for developing plans and appropriate actions for the Phase II activities. Site personnel are currently evaluating various options, i.e. casing perforation with grout injection or partial well abandonment, to eliminate the downward flow in the gravel pack at the altitude of the McQueen Branch Confining Zone. In addressing potential remediation actions for the dissolved solvents in the Cretaceous sediments, due to the limited vertical extent of the plume and the size, any remediation program should incorporate carefully located wells screened vertically within the plume trajectory.This optimizing approach will minimize water treatment and pumping costs and maximize the amount of contaminant removal. Flow and contaminant transport modeling scenarios are currently being developed to address the Cretaceous sediments. These efforts involve incorporating the available characterization data and the results of previous modeling work to more precisely define the extent and magnitude of this plume. SRS proposes incorporating depth discrete sampling during any future characterization effort to optimize any proposed remediation system. Finally, by using a full three-dimensional model rather than the traditional quasi-three dimensional methods an efficient remediation system can be developed.