Balancing the Costs of Short-Term Cleanup and Long-Term Stewardship During Remedial Planning

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1 Balancing the Costs of Short-Term Cleanup and Long-Term Stewardship During Remedial Planning Jeff Carnahan Vice President Chief Technical Officer EnviroForensics, Inc.

2 Example Clean-Up v. LTS Operated as a dry cleaner from early 1980s until 2007 Operational releases over time Geological and Contaminant Distribution CSM Upper 10 feet of soil is cohesive Clayey Silt, underlain by a poorly graded fine-medium grain Sand Soil impacts of tetrachloroethene (), max 36 ppm Groundwater at 30 feet bgs, max 125 ppb beneath source Soil gas plume extends beyond site boundaries Located in a mixed residential and commercial area Multi-family, senior housing building adjacent

3 Distribution in Soil

4 Scenario Background Indiana Site

5 Risk Evaluation and Point of Exposure Assessment Groundwater plume is stable and dilute (not above VIGWSLs), but above MCLs. Potential exposure. Soil impacts are in excess of migration to groundwater levels, but not direct contact thresholds. Potential exposure. Vapor Intrusion exposure pathway is potentially complete, and largely a result of impacted soils in shallow fine-grained zone, and residual soil gas plume in deeper sand. Potential exposure.

6 Remedial Planning Selected approach will result from analysis of variable amounts of contaminant mass removal in soil and groundwater, vs. scope of anticipated Long-Term Monitoring & Stewardship requirements. $ Remedy $ LTS

7 Current Conditions RECEPTOR SOIL GW VAPOR

8 Remedial Scenario 1 Further Site Investigation Long-Term Monitoring (50 Years) Annual Institutional Control Verification/Inspection Groundwater use restriction Future excavation/construction restriction Operation of existing/proposed SSDS systems Annual Sampling Annual groundwater sample collection Annual worst-case vapor intrusion sampling Monitoring Well Abandonment and Case Closure

9 Remedial Scenario 1 RECEPTOR CONTROL CONTROL CONTROL SOIL GW VAPOR

10 Remedial Scenario 2 Further Site Investigation Building Demolition and Shallow Excavation Activities Long-Term Monitoring (25 Years) Annual Institutional Control Verification/Inspection Groundwater use restriction Operation of existing/proposed SSDS systems Annual Sampling Annual groundwater sample collection Annual worst-case vapor intrusion sampling Monitoring Well Abandonment and Case Closure

11 Remedial Scenario 2 RECEPTOR CONTROL CONTROL SOIL EXCAVATE GW VAPOR

12 Remedial Scenario 3 Further Site Investigation Building Demolition and Shallow Excavation Activities Soil Vapor Extraction in Deeper Sand Groundwater Polishing Long-Term Monitoring (5 Years) Annual Institutional Control Verification/Inspection Groundwater use restriction only Operation of existing/proposed SSDS systems Annual Sampling Annual groundwater sample collection Annual worst-case vapor intrusion sampling Monitoring Well Abandonment and Case Closure

13 Remedial Scenario 3 RECEPTOR SOIL GW VAPOR EXCAVATE LIGHT TMNT SVE

14 Hypothetical Lengths of LTS Scenario 1 Scenario 2 Scenario 3 Remediation Approach No Source Treatment Excavation Excavation with Soil Vapor Extraction and Groundwater Treatment Long-Term Monitoring Duration 50 Years of Monitoring (50 total years) 25 Years of Monitoring (25 total years) 5 Years of Monitoring (10 total years)

15 Cost Summary of Scenarios Scenario 1 Further Site Investigation 50 Years Long-Term Stewardship Regulatory Fees and Case Closure Scenario 2 Further Site Investigation Source Excavation Progress Monitoring 25 Years Long-Term Stewardship Case Closure Scenario 3 Further Site Investigation Source Excavation SVE and Groundwater Remediation Progress Monitoring 5 Years Long-Term Stewardship Case Closure Further Site Investigation $ 60,000 $ 60,000 $ 60,000 Remediation $ 25,000 $ 440,000 $ 1,340,000 Remediation Planning and Coordination $ 25,000 $ 50,000 $ 70,000 Transport and Remediation Modeling $ 25,000 $ 25,000 $ 5,000 Source Excavation $ - $ 285,000 $ 285,000 Soil Vapor Extraction $ - $ - $ 350,000 Groundwater Remediation $ - $ - $ 200,000 Remedial Action Design Report $ - $ 20,000 $ 30,000 Progress Sampling and Plume Behavior $ - $ 60,000 $ 400,000 Long-Term Stewardship $ 3,366,330 $ 1,713,165 $ 390,633 Closure Costs $ 50,000 $ 50,000 $ 50,000 Regulatory Review Fees $ 75,000 $ 37,500 $ 15,000 20% Contingency $ 715,266 $ 460,133 $ 371,127 PROJECT TOTAL $ 4,291,596 $ 2,760,798 $ 2,226,760 Years

16 Phase Breakdown of Scenarios $2,500,000 $2,000,000 $1,500,000 $1,000,000 $500,000 $0 FSI Remediation Work Plan Preparation Scenario 3 Further Site Investigation Source Excavation SVE and Groundwater Remediation Progress Monitoring 5 Years Long-Term Stewardship Case Closure Remediation Remediation Monitoring Closure Scenario 2 Further Site Investigation Source Excavation Progress Monitoring 25 Years Long-Term Stewardship Case Closure Scenario 1 Scenario 2 LTS (0-5 years) Scenario 3 LTS (5-25 Scenario 1 years) LTS (25-50 Further Site Investigation years) 50 Years Long-Term Stewardship Regulatory Fees and Case Closure

17 Cumulative Cost Summary of Scenarios $4,500,000 $4,000,000 $3,500,000 $3,000,000 $2,500,000 $2,000,000 $1,500,000 $1,000,000 $500,000 $0 FSI Remediation Work Plan Preparation Remediation Scenario 3 Further Site Investigation Source Excavation SVE and Groundwater Remediation Progress Monitoring 5 Years Long-Term Stewardship Case Closure Remediation Monitoring Closure Scenario 2 Further Site Investigation Source Excavation Progress Monitoring 25 Years Long-Term Stewardship Case Closure LTS (0-5 years) Scenario 1 Scenario 2 Scenario 3 LTS (5-25 years) LTS (25-50 Scenario 1 years) Further Site Investigation 50 Years Long-Term Stewardship Regulatory Fees and Case Closure

18 Predicting Required Term of LTS Predicting life of Interim necessary LTS activities is part of cost analysis as discussed It is also necessary as part of Remedial Work Plan for Agency consideration Following Simplified Example; Large GW Plume

19 Predicting Required Term of LTS RECEPTOR SOIL GW VAPOR

20 Predicting Required Term of LTS RECEPTOR SOIL INTERIM CONTROL GW REMEDY VAPOR

21 $15 Million

22 $2.0 Million

23 $6.5 Million

24 $3.0 Million

25 Summary of Key Points LTS Requirements are here The associated costs to implement LTS obligations will play a large role during remedial selection The cost analysis of active remedy v. pathway elimination may more often than not result in substantiated mass removal

26 Balancing the Costs of Short-Term Cleanup and Long-Term Stewardship During Remedial Planning Thanks! Questions?