Theme: 10. Characterization, Fate and Transport

Topic Area: 10f. High-Resolution Site Characterization (HRSC)

Formatted Title:

High-Resolution Design Optimization (HRDO) and Injection at Brookley AFB Mobile, Alabama

Background/Objectives:

The U.S. Air Force (USAF) reportedly used AOC-009 for burning waste oil, fuel, and solvents during fire training exercises. Contaminants of concern include trichloroethylene (TCE); 1,2-DCA; (cis)-1,2-DCE; and VC. In January 2013, an in situ chemical reduction (ISCR) injection pilot study consisted of in situ injection of EHC, which is a mixture of micro-scale zero valent iron (ZVI) and food grade organic carbon nutrients. In 2017, an FS was completed and recommended saturated zone residual source area ISCR via soil mixing, elevated concentration plume area ISCR injections, and plume area EMNA. This case study addresses the ISCR and EISB injections where Delmonico PKS JV LLC teamed with Cascade Environmental and were awarded the project.

Approach/Activities:

A key aspect of the team’s proposal was to optimize their approach through HRDO to further define contaminant mass distribution versus lithology targeting. MiHPT and confirmation soil and groundwater samples were used to define three unique approaches taking into account contaminant mass and lithology. A total of 11 MiHPT investigation borings were advanced during the predesign phase of the field work.

The HRDO resulted in a significant, but optimized departure from the as-bid scope of work, with both liquid and solid ISCR amendments injected as follows:

Area 1: Source area with EHC/DPT injections - Mg(OH)2 and DHC
Area 2: Outside source area with EHC/DPT - Mg(OH)2 and DHC
Area 3: EISB with ELS - DHC and Buffer NaHCO3
Area 4: ISCR-BIO-GEO with Geoform soluble + DHC

Results/Lessons Learned:

The pre- and post-HRDO injection plan and the rationale on the overall injection approach, chemistry selection, and equipment utilized by Cascade will be presented. Additionally post remediation data will be presented from the first and second quarters of 2023, and later sampling events as they become available. Lessons learned during the HRDO, design, and injection will also be presented.

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Michael Gerber