(137d) Effective Field Characterization of a Groundwater Tce in Fractured Basalt

This presentation will provide valuable lessons learned from a recently completed TCE groundwater characterization effort in fractured basalt aquifers and will demonstrate the effectiveness of the Triad approach from project planning, implementation, and evaluation through project completion to regulatory acceptance. The presentation will assess data management and evaluation, team roles, project bottlenecks, data visualization, data gaps and uncertainty management, and regulatory acceptance.

In 2004 and 2005, U.S. Army Corps of Engineers, Seattle District, conducted a field investigation that combined multiple investigation and analytical methods to further characterize low-level TCE plumes in fractured basalt aquifers at a Superfund site (former Larson Air Force Base in Moses Lake, Washington). The field plan was developed using systematic planning to create a dynamically-structured strategy for the field work to progress in a way to best meet project objectives based on an evolving conceptual site model. The plan was designed to allow the project team to make real-time decisions during field work to complete the remedial investigation phase of work and provide remaining necessary information for a feasibility study. The dynamic approach employed by the project team was dependent upon a detailed management plan (describing investigation methodologies, rationales, and sequencing), multi-discipline field and office teams with a mix of experience and expertise, partnering with regulators, traditional and innovative field investigation methods (drilling: air rotary, sonic, enhanced CPT; sampling: in-situ drilling samples, passive diffusion bag samplers, low-flow sampling), fixed and field analytical techniques (quick-turn fixed laboratory and on-site Direct Sensing Ion-Trap Mass Spectrometry), and progressive electronic data management (SEDD deliverables, web-based data tables and interactive web formats for coordination between field team, contractors, and in-house USACE and EPA teams).