United States Robert S. Kerr EPA/600/8-90/003 Environmental Protection Environmental Research Laboratory March 1990 Agency Ada OK 74820 Research and Development Basics of Pump-and-Treat Ground-Water Remediation Technology Word-searchable version – Not a true copy EPA-600/8-90/003 Basics of Pump-and-Treat Ground-Water Remediation Technology James W. Mercer, David C. Skipp and Daniel Giffin Geo Trans, Inc. 250-A Exchange Place Herndon, Virginia 22070 Project Officer Randall R. Ross Extramural Activities and Assistance Division Robert S. Kerr Environmental Research Laboratory Office of Research and Development U.S. Environment Protection Agency Ada, Oklahoma 74820 Word-Searchable Version – Not a true copy Disclaimer The Information in this document has been funded in part by the United States Environmental Protection Agency under Contract No. 68-C8-0058 to Dynamac Corporation. It has been subjected to the Agency's peer and administrative review, and it has been approved for publication as an EPA document. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. ii Word-searchable version – Not a true copy Foreword EPA is charged by Congress to protect the nation's land, air and water systems. Under a mandate of national environmental laws focused on air and water quality, solid waste management and the control of toxic substances, pesticides, noise and radiation, the Agency strives to formulate and implement actions which lead to a compatible balance between human activities and the ability of natural systems to support and nurture life. The Robert S. Kerr Environmental Research Laboratory is the Agency's center of expertise for investigation of the soil and subsurface environment. Personnel at the Laboratory are responsible for management of research programs to: (a) determine the fate, transport and transformation rates of pollutants in the soil, the unsaturated and the saturated zones of the subsurface environment; (b) define the processes to be used in characterizing the soil and the subsurface environment as a receptor of pollutants; (c) develop techniques for predicting the effect of pollutants on ground water, soil, and indigenous organisms; and (d) define and demonstrate the applicability and limitations of using natural processes, indigenous to soil and subsurface environment, for the protection of this resource. The pump-and-treat process, whereby contaminated ground water is pumped to the surface for treatment, is one of the most common ground-water remediation technologies used at hazardous waste sites. However, recent research has identified complex chemical and physical interactions between contaminants and the subsurface media which may impose limitations on the extraction part of the process. This report was developed to summarize the basic considerations necessary to determine when, where, and how pump-and-treat technology can be used effectively to remediate ground-water contamination. Clinton W. Hall /s/ Director Robert S. Kerr Environmental Research Laboratory iii Word-searchable version – Not a true copy Table of Contents Page FOREWARD .............................................................................. iii FIGURES .................................................................................vi TABLES ................................................................................. vii INTRODUCTION ............................................................................1 Purpose of report ......................................................................1 Format of report ......................................................................1 OVERVIEW ...............................................................................1 DATA REQUIREMENTS ......................................................................3 Hydrogeological data ...................................................................3 Contaminant data .....................................................................4 Data collection .......................................................................7 Data interpretation .................................................................... 10 CONCEPTUAL DESIGN ...................................................................... 11 When to select pump-and-treat systems .................................................... 11 Example of contaminant plume delineation and pump-and-treat implementation ........................ 13 Calculating the estimated cleanup time ..................................................... 14 Limitations of pump-and-treat systems......................................................... 15 Design considerations ................................................................. 19 Determining well spacings, pumping rates, and time required for cleanups ............................ 19 Example of gasoline spill ............................................................... 22 OPERATION AND MONITORING ............................................................... 23 Remedial action objectives .............................................................. 23 Monitoring .......................................................................... 23 Evaluation and modification of existing pump-and-treat systems ................................... 23 REFERENCES ............................................................................ 25 GLOSSARY .............................................................................. 29 APPENDIX A - Chemical Data.................................................................... A-1 APPENDIX B - Pump-and-Treat Applications ...................................................... B-1 v Word-searchable version – Not a true copy List of Figures Page 1. Example setting where a pump-and-treat system is used ............................................2 2. Plan view of contaminant plume spreading by advection and dispersion (from Keely, 1989) ....................5 3. Trapped oil at residual saturation (from API, 1980) .................................................7 4. Water-oil relative permeability versus water saturation ..............................................8 5. S-Area site, Niagara Falls, New York, showing proposed containment system ............................ 12 6a. Decision-flow diagram for ground-water contamination .............................................. 12 6b. Decision-flow diagram for soil contamination .................................................... 13 7. Effects of tailing on pumping time (from Keeley et al., 1989) ......................................... 15 8. Liquid partitioning limitations of pump-and-treat effectiveness (from Keely, 1989) ........................... 17 9. Sorption limitations to pump-and-treat effectiveness (from Keely, 1989) ................................. 17 10. Effect of geologic stratification on tailing (from Keeley et al., 1989) .................................... 18 11. Calculated VOC inventory versus time (from Ward et al., (1987) ...................................... 20 12. Calculated extraction well concentrations versus time (from Ward et al., 1987) ............................20 13. Simulation to capture front of the plume: 10 wells, 25 feet apart, pumping at 2 gpm each .....................21 14. Flowline pattern generated by an extraction well (from Keely, 1989) .................................... 24 15. Reduction of residual contaminant mass by pulsed pumping (from Keely, 1989) ........................... 24 vi Word-searchable version – Not a true copy List of Tables Page 1. Aspects of site hydrogeology (U.S. EPA, 1988) .................................................4 2. Data pertinent to ground-water contamination characterization (from Bouwer et al., 1988) ....................6 3. Potential sources of information (Knox et al., 1986) ...............................................8 4. Data collection methods (references provided in text) ..............................................9 5. Favorable and unfavorable conditions for pump-and-treat technologies ................................. 16 6. Phase distribution of gasoline in sand and gravel (Brown et al., 1988) .................................22 vii Word-searchable version – Not a true copy hydrogeological environments can be treated successfully Introduction with pump-and-treat technology and those for which pump- and-treat systems need to be supplemented with other Purpose of report remedial technologies. A common means to contain and/or remediate The final section, Operation and Monitoring, emphasizes contaminated ground water is extracting the water and the need for setting remedial action objectives and for treating it at the surface, which is referred to as pump-and- monitoring to ensure that these goals are attained. Once treat technology. This report provides basic guidance on the pump-and-treat system is implemented, adjustments how to use available hydrogeological and chemical data to and modifications invariably will be required. Ways to determine when, where, and how pump-and-treat evaluate the pump-and-treat system are discussed along technology can be used successfully to contain and/or with typical modifications. remediate contaminant plumes. Ways to estimate the time required to achieve a specific ground-water cleanup goal Appendices provide (1) data on various chemicals that are also are discussed. Finally, the report addresses practical relevant to pump-and-treat systems and (2) a summary of limitations