COLLECTING AND INTERPRETING SOIL GAS SAMPLES FROM THE VADOSE ZONE - A PRACTICAL STRATEGY FOR ASSESSING THE SUBSURFACE VAPOR-TO-INDOOR AIR MIGRATION PATHWAY AT PETROLEUM HYDROCARBON SITES
American Petroleum Institute
1.0 Introduction
2.0 Soil Gas Transport and Soil Gas Profiles at Petroleum
Hydrocarbon Impacted Sites
2.1 Expectations for Soil Gas Profiles at Petroleum Hydrocarbon
Impacted Sites
2.2 Measured Soil Gas Profiles at Petroleum Hydrocarbon Impacted
Sites
3.0 Conceptual Migration Model for Subsurface Vapor to Indoor Air
4.0 Development of a Strategy for Soil Gas Sampling
4.1 General Approach
4.2 Point Sampling
4.3 Transects and Vertical Profiles
4.3.1 Selection of Lateral Positions for Soil Gas Transects
4.3.2 Vertical Profiles
4.4 Summary of Sampling Depth and Location Selection Considerations
4.5 Some Comments on Sample Collection Adjacent to and Beneath
Buildings
4.6 Sampling Frequency
4.7 Additional Considerations to Increase Confidence in Data Sets
and the Interpretation of Soil-Gas-Sampling Results
5.0 Soil Gas Sample Collection
5.1 Basic Monitoring Installation Options
5.1.1 Permanent Probes
5.1.2 Temporary Driven Probes
5.2 Comparison of Monitoring Installations
5.3 Other Considerations for Sampling Probe Installations
5.4 Sample Collection Procedures
5.4.1 Soil Gas Equilibration
5.4.2 Sample Probe Purging
5.4.3 Sample Collection
5.4.4 Sample Collection Vacuum
5.5 Ways to Avoid Common Problems with Soil Gas Sampling
5.6 Alternatives to Soil Gas Sampling
5.6.1 Passive Implant Samplers
5.6.2 Flux Chambers
6.0 Analytical Methods
6.1 Analytical Method Selection
6.1.1 Field Analytical Methods
6.1.2 Common Analytical Methods
6.2 Data Quality
7.0 Analysis and Interpretation of Soil Gas Sampling Data
7.1 Data Organization
7.2 Data Analysis
7.2.1 Data Quality Analysis
7.2.2 Data Consistency Analysis
7.3 Exposure Pathway Assessment
7.3.1 Exposure Pathway Completeness
7.3.2 Exposure Pathway Significance
7.4 Further Evaluation
8.0 References
9.0 Additional Reading
9.1 Analytical Methods
9.2 Biodegradation
9.3 Data Analysis
9.4 General
9.5 Modeling
9.6 Sample Collection Methods
9.7 Site Characteristics and Conceptual Vapor-Migration Models
Appendix A. Characteristics Checklist
Appendix B. Selection of Soil Gas Sample Locations
Appendix C. Soil Gas Sample Collection
Appendix D. Analytical Methods
Appendix E. Data Evaluation
Figures
Tables
Focuses on the collection of soil gas samples for assessing the significance of the subsurface-vapor-to-indoor-air exposure pathway.
| Document Type | Standard |
| Status | Current |
| Publisher | American Petroleum Institute |
