Theme: 02. Assessing Remediation Effectiveness

Topic Area: 02h. Optimizing Remedial Systems

Formatted Title:

Bioaugmentation Design for Treatment of High-Level Source Area Contaminated with Explosives

Background/Objectives:

The former West Virginia Ordnance Works, near Point Pleasant, West Virginia, was used by the U.S. Army to manufacture 2,4,6-trinitrotoluene (TNT) during the early 1940s. Currently the land is managed as part of the McClintic Wildlife Management Area. Residual nitroaromatic contamination is present in some areas of the site, which is listed on the National Priorities List (NPL). Aptim conducted an optimization study from 2013 to 2018, which included an evaluation of the current pump and treat remedy at the former Pond 13 Wet Well Area and remedial actions to expedite site restoration. Field-scale treatability studies conducted 2008 to 2009 and 2017 to 2019 proved the effectiveness of bioaugmentation at the site; however, contaminants were not reduced to below the remedial goals due to the large mass of explosives source material.

Approach/Activities:

Previous groundwater monitoring events revealed concentrations of TNT as high as 31,000 µg/L at the Pond 13 Wet Well Area. Results from the HRSC investigation were utilized to identify preferential flow paths in the intermediate water-bearing zone and update the conceptual site model (CSM). These results also better defined the nature and extent of contamination and eliminated data gaps. Aptim developed an initial design approach which was presented to stakeholders (client, federal regulators, and state regulator) in a Total Project Planning (TPP) meeting to solicit input and gain stakeholder buy-in to the approach. As of the date of this abstract, Aptim has developed a conceptual draft design consisting of a combination of direct injection of colloidal activated carbon (CAC), sulfidated micro zero valent iron (S-mZVI) and a non-oil-based electron donor product in the most highly contaminated area and a recirculation system consisting of injection and extraction of Sodium Lactate in a larger, less contaminated area. Existing monitoring wells will be monitored quarterly for one year, semiannually for one year, then annually until remedial goals are achieved. There will be a contingency for reinjection if required based on monitoring results.

Results/Lessons Learned:

The updated CSM, the detailed design, and associated costs for implementation will be presented as well as potential cost savings by eliminating the existing pump and treat system. The TPP process involving all stakeholders throughout the design development will also be presented. Lessons learned associated with utilization of HRSC data for the design and implementation of the TPP process will be discussed.

Zach Parham

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Bioaugmentation Design for Treatment of High-Level Source Area Contaminated with Explosives