Basis for Exit Strategy Development

Transcription

1 Adaptations to Triad as a Basis for Exit Strategy Development Anthony Pennino May 22, Joint Services Environmental Management Conference Columbus, OH Presented By

2 Presentation Objectives Present a unique Triad approach Describe value-added Triad adaptations which: Used a semi-quantitative decision making tool for real-time assessment of remediation viability Optimized data collection based on a remediation viability score Reduced uncertainty in site management of a TCE source and groundwater plume Illustrate how the results were used to develop a Site Direction statement and provide a basis for follow-up Exit Strategy formulation

3 Successful Strategies Condense into a Central Theme ( what ) + 3 Elements ( how ) of the Triad Approach Systematic Project Planning Uncertainty Management Dynamic Work Strategies Real-time Measurement Technologies

4 ST-123, Hurlburt Field, FL Contains an active POL fuel yard, flightline, and aircraft maintenance building Suspected source of TCE is a former radio and radar shop along flightline A typical DNAPL remediation site

5 Rationale for Triad at ST-123 Triad approach selected to mitigate additional reactionary iterations of investigation: Initially the site was identified as a POL site Three initial assessments were completed with the third finding a dirty upgradient well A fourth investigation targeted high uncertainty in vertical delineation of the source Multiple HRC test injections were conducted Three years later, contamination migrated 300 lateral feet and 40 vertical feet and source concentrations rebounded in the treatment zone

6 Systematic Planning Source area uncertainty identified as a key data gap and would require most $ to address Considered future remedial efforts as a gauge for defining degree of delineation Tiered objectives were established: Identify target treatment areas Determine feasibility of No Further Action (NFA) or aggressive site remedy for source areas

7 Prioritized Data Objectives Item Project Objective Tier 1 Field Activities (High Priority Needs) Tier 2 Field Activities (Medium Priority Needs) Tier 3 Field Activities (Low Priority Needs) 2 Delineation of Source Area Identify Target Treatment Areas Determine if NFA is a feasible option at ST Characterization of Source Materials in Lower Intermediate Zone (50-80 ft bgs) 2. Characterization of Source Materials in Deep Zone ( ft bgs) Sample Most Biased Locations First, Stop if nothing there Develop Non-parametric Relationship between MIP and laboratory concentrations 1. Characterization of Source Materials in Shallow Zone (7-40 ft bgs) 2. Characterization of Source Materials in Upper Intermediate Zone (40-50 ft bgs) 3. Delineation of Vadose Zone Contamination (0-7 ft bgs) 3 Obtain Conceptual Design Data for Potential Remediation Delivery Process Information: Soil type, density, grain-size distribution, conductivity, permeability, porosity Obtain ISCO parameters (if applicable) Natural oxidant demand (NOD) Tests Total organic carbon (TOC) data 1.Enhanced Bioremediation Microbial analysis 2.Obtain ISCR parameters Determine reducing agent scavenger concentrations 6. Develop Exit Strategy Acceptable to EPA, FDEP, and Air Force Data for this objective will be obtained through other objectives.

8 Dynamic Work Strategies Used NFA Feasibility Screening Matrix to adjust field data collection program and reprioritize data objectives Also developed to assist project stakeholders in deciding whether to proceed with a No Further Action (NFA) remedy for a particular source area or some other alternative

9 NFA Feasibility Screening Matrix AVERAGE TOTAL MIN MAX Item Criteria Score Technical Factors 1 Is the source on-going and continuing to add mass to the subsurface? Is there a potential or real risk to human or ecological exposure from the contaminants of the source? Is residual or mobile DNAPL suspected to be ABSENT in vadose or saturated zone soil samples? If residual or mobile DNAPL is present, is its architecture amenable to cost-effective remediation? Is the source geometry well characterized? Is the extent of the source material of reasonable size/depth for cost-effective remediation? Is delivery of in-situ amendments into the target treatment zone feasible? Is a cost-effective technology available and proven to remediate the source to the remedial action objectives? Are the numeric remedial action objectives realistic (i.e., not MCLs)? Is the lithology of the source area simple? Are the aquifer hydraulic conditions within the source area amenable to remediation? Are quantitative tools available and implementable to provide cost:benefit analysis and remediation progress monitoring? Is NA activity present which may support, with or without amendment, an MNA polishing step after source treatment? Have realistic remediation timeframe estimates been set based on site-specific conditions (using SourceDK model or similar)? Subtotal Technical Factors Non-Technical (Intangible) Factors 15 Are near-term site use goals (i.e., less than 30 years) strict enough to require source area remediation to NFA? Does current site infrastructure and use allow for relatively unimpeded site remediation activities? Is there a strong desire to reduce contaminant mass and thereby reduce the environmental burden of future generations? Are the project stakeholders willing to accept a relatively high level of risk in seeking, and possibly failing, to remediate to NFA? Is there a strong committment to test new technologies and advance the science of DNAPL remediation? Subtotal Non-Technical Factors TOTAL TOTAL SCORE INTERPRETATION: If one or more GREEN cells appear, then the certainty score is irrelevant. MORE aggressive remediation techniques should be strongly considered. If multiple RED cells appear, then the certainty score is irrelevant. LESS aggressive remediation techniques should be strongly considered. >14 - The site is extraordinarily well suited for aggressive source remediation Indicators favor some degree of aggressive source remediation, less inherent risk of success with scores at the higher end of the range Around the 50/50 mark, stakeholders will have to closely weigh the pros and cons of aggressive source remediation Less aggressive source remediation approached are recommended. Stakeholders should consider alternative less aggressive or partial mass removal technologies <4 - The project conditions are not amenable to source remediation and stakeholders should consider containment or long-term monitoring/land use control options. If additional certainty is required by the project team, then additional data collection must be performed in order to close data gaps.

10 Exit Strategy Screening Results Each team member scored each source area separately and an average was taken Average scores for each of the 3 identified sources indicated that less aggressive source remediation approaches, such as partial mass removal, may be best site options Results were used to adjust field data collection program and as a basis for writing the Triad report (Site Direction)

11 Preliminary Site Conceptual Model

12 Final Conceptual Site Model

13 Site Direction Primary product of the Triad effort Precursor to Exit Strategy due to need for additional risk assessment Resultant strategy for ST-123 included: Risk assessment to define numeric cleanup criteria Remediation to reduce mass in known source zones Use of natural attenuation to treat the dissolvedphase groundwater plume where feasible Use of observational-approach decision logic that prescribes method to maintain cost-effective remedial progress Industrial land use controls (LUCs)

14 Lessons Learned for Future Adaptation Team members should be aware of the regulatory framework governing the site so remedial efforts can be accurately assessed real-time Incorporating prioritized data needs into the Dynamic Work Plan decision logic can help to optimize data collection Short pauses, not re-mobilization, in field work to evaluate schedule, budget, and data need priorities are beneficial Consensus by the entire team is essential so decisions can be made efficiently and the right people empowered at the right time to execute the work

15 Conclusions In a 4-month field investigation, developed a significantly more comprehensive understanding of the site The framework for an Exit Strategy was developed, which is consistent with: Site conditions Regulatory protocol Air Force long-term management goals Technology constraints Because decision uncertainty was greatly reduced, the future project scope can be narrowed and the longterm project costs reduced

16 Acknowledgments Jeff Lockwood, P.E., Florida Department of Environmental Protection (FDEP) Craig Benedict, U.S. Environmental Protection Agency (EPA) John Steele- HQ AFSOC A7/AV Art Kolodziejski Formerly with HQ AFSOC now with EUCOM Chris Hood, Tom Palaia, and Kim-Lee Murphy CH2M HILL Joann Socash Booz Allen Hamilton Supporting AFCEE David Miller National Argonne Lab Triad Expert and Facilitator

17 Presented By Questions?