The DNAPL Remediation Challenge: Is There a Case for Source

1,09

MB

Depletion?

129

stron

6489

ID

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

2004

rok

Contents

Notice ii

Foreword iii

Acknowledgments . ix

Executive Summary . x

1.0 Introduction 1

1.1 Background .1

1.2 Expert Panel Formation .2

1.3 Organization of the Report 3

2.0 Problem Description .5

2.1 DNAPLs as a Source of Groundwater Contamination .5

2.2 Magnitude of the Problem .5

2.3 Regulatory Framework 6

2.4 Technical Framework 7

3.0 Questions .11

3.1 Question 1: What are the Potential Benefi ts and Potential Adverse Impacts of DNAPL Source

Depletion as a Remediation Strategy? 11

3.1.1 Potential Benefi ts of Partial Source Depletion 11

3.1.2 Potential Adverse Impacts from Use of Aggressive Technologies for Source Depletion 14

3.1.3 Summary 15

3.2 Question 2: What are the Appropriate Performance Metrics for Assessment of DNAPL Source

Depletion Technologies? 16

3.2.1 Type I Metrics 16

3.2.2 Type II Metrics .17

3.2.3 Type III Metrics 18

3.2.4 Summary 18

3.3 Question 3: Are Available Technologies Adequate for DNAPL Source Characterization to Select

and Evaluate Depletion Options? 18

3.3.1 Innovations in Site Characterization Approaches .19

3.3.2 Innovations in Site Characterization Tools 19

3.3.3 Summary 23

3.4 Question 4: What Performance can be Anticipated from DNAPL Source-Zone Depletion

Technologies? 23

3.4.1 Status of Development and Deployment of DNAPL Source-Zone Depletion Technologies .24

3.4.2 Anticipated Effectiveness of DNAPL Source-Zone Depletion Technologies .29

3.4.3 Cost of DNAPL Source Depletion Technologies .31

3.4.4 Summary 32

3.5 Question 5: Are Currently Available Tools Adequate to Predict the Performance of Source

Depletion Options? 32

3.5.1 Numerical Models: Deterministic Approaches 32

3.5.2 Numerical/Analytical Models: Stochastic Approaches 33

3.5.3 Guidance Documents .34

3.5.4 Case Studies and Pilot Tests 34

3.5.5 Limitations of Existing Tools 35

3.5.6 Summary 36

3.6 Question 6: What are the Factors Limiting the Effective and Appropriate Application of Source

Depletion Technologies? 36

3.6.1 Defi nition of Remedial Objectives Requiring Restoration in Source Zones .36

3.6.2 Uncertainty in Predicting Likelihood of Success at a Given Cost 36

3.6.3 Lack of Well-Documented Successes 37

3.6.4 Availability and Cost of Insurance .37

3.6.5 Limited Number of Qualifi ed Vendors .37

3.7 Question 7: How Should Decisions be Made Whether to Undertake DNAPL Source Depletion? 38

4.0 Knowledge Gaps and Research Needs 41

4.1 Introduction .41

4.2 Performance Metrics 41

4.2.1 Knowledge Gaps .41

4.2.2 Research Needs 41

4.3 Site Characterization .41

4.3.1 Knowledge Gaps .41

4.3.2 Research Needs .41

4.4 DNAPL Source-Zone Depletion Technologies .42

4.4.1 Knowledge Gaps .42

4.4.2 Research Needs .42

4.5 Performance Prediction Tools 42

4.5.1 Knowledge Gaps .42

4.5.2 Research Needs .43

4.6 Decision Analysis Tools .43

4.6.1 Knowledge Gaps .43

4.6.2 Research Needs .43

5.0 Conclusions and Recommendations .45

5.1 Conclusions .45

5.2 Recommendations .47

6.0 List of References and Bibliography 49

Appendices

A Case Studies .59

B Biosketches of Panel Members .97

C Workshop Agenda – Dallas, TX .104

D List of Attendees – Dallas, TX .107