FINAL PROJECT REPORT

A Systematic Approach

for Evaluation of Capture Zones

at Pump and Treat Systems

Office of Research and Development

National Risk Management Research Laboratory | Ground Water and Ecosystems Restoration Division

EPA 600/R-08/003 | January 2008 | www.epa.gov/ord
EPA/600/R-08/003

January 2008

A Systematic Approach for 

Evaluation of Capture Zones at 

Pump and Treat Systems

Project Officer

David S. Burden

Ground Water and Ecosystems Restoration Division

U.S. EPA, National Risk Management Research Laboratory

Ada, OK 74820

National Risk Management Research Laboratory

Office of Research and Development

U.S. Environmental Protection Agency

Cincinnati, OH 45268

To download this and other EPA/ORD/NRMRL/GWERD publications visit http://www.epa.gov/ada/

Office of Research and Development

National Risk Management Research Laboratory | Ground Water and Ecosystems Restoration Division
NOTICE

The U.S. Environmental Protection Agency through its Office of Research and Development and 

the Office of Superfund Remediation and Technology Innovation funded and managed the research 

described herein. This document was prepared by GeoTrans, Inc. for the U.S. Environmental Protection 

Agency (U.S. EPA) under Tetra Tech Contract No. 68-W-02-034, Subcontract No. G9015.0.037.03.01, 

and under Dynamac Contract No. 68-C-02-092, Subcontract No. 092580. It has been subjected to the 

Agency`s review and has been approved for publication as an EPA document. No official endorsement 

should be inferred. Mention of trade names or commercial products does not constitute endorsement or 

recommendation for use.

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FOREWORD

The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation’s land, air, 

and water resources. Under a mandate of national environmental laws, the Agency strives to formulate 

and implement actions leading to a compatible balance between human activities and the ability of natural 

systems to support and nurture life. To meet this mandate, EPA’s research program is providing data 

and technical support for solving environmental problems today and building a science knowledge base 

necessary to manage our ecological resources wisely, understand how pollutants affect our health, and 

prevent or reduce environmental risks in the future. 

The National Risk Management Research Laboratory (NRMRL) is the Agency’s center for investigation 

of technological and management approaches for preventing and reducing risks from pollution that 

threatens human health and the environment. The focus of the Laboratory’s research program is on 

methods and their cost-effectiveness for prevention and control of pollution to air, land, water, and 

subsurface resources; protection of water quality in public water systems; remediation of contaminated 

sites, sediments and ground water; prevention and control of indoor air pollution; and restoration of 

ecosystems. NRMRL collaborates with both public and private sector partners to foster technologies that 

reduce the cost of compliance and to anticipate emerging problems. NRMRL’s research provides solutions 

to environmental problems by: developing and promoting technologies that protect and improve the 

environment; advancing scientific and engineering information to support regulatory and policy decisions; 

and providing the technical support and information transfer to ensure implementation of environmental 

regulations and strategies at the national, state, and community levels. 

This document describes a systematic approach for performing capture zone analysis associated with 

ground-water pump and treat (P&T) systems. The intended audience is technical professionals that 

actually perform capture zone analyses (i.e., hydrogeologists, engineers) as well as project managers who 

review those analyses and/or make decisions based on those analyses. 

 

Stephen G. Schmelling, Director

Ground Water and Ecosystems Restoration Division

 National Risk Management Research Laboratory

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CONTENTS

A. INTRODUCTION...................................................................................................................................1

B. A SYSTEMATIC APPROACH FOR CAPTURE ZONE ANALYSIS...................................................5

C. SUMMARY...........................................................................................................................................31

D. GLOSSARY AND SELECTED ABBREVIATIONS ...........................................................................33

E. REFERENCES......................................................................................................................................35

APPENDIX A: EXAMPLES FOR THREE HYPOTHETICAL SITES

EXAMPLE A1........................................................................................................................... A1-1

EXAMPLE A2........................................................................................................................... A2-1

EXAMPLE A3........................................................................................................................... A3-1

APPENDIX B: EXAMPLES FOR TWO ACTUAL SITES

EXAMPLE B1............................................................................................................................B1-1

EXAMPLE B2............................................................................................................................B2-1

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EXHIBITS

1. Six Steps for Systematic Evaluation of Capture Zones.......................................................................... 4

2. Elements Associated with Step 1 (Prerequisites for a Capture Zone Evaluation).................................. 5

3. Issues When Evaluating Horizontal Capture from Water Level Contour Maps ...................................11

4. Using Specific Capacities From a Step-Drawdown Test to Estimate

Well Losses at Extraction Wells due to Turbulent Flow ...................................................................... 17

5. Questions to Ask When Performing Simple Horizontal Capture Analyses ......................................... 22

6. Items to Address after Actual Capture is Interpreted ........................................................................... 26

7. Capture Zone Analysis – Iterative Approach ....................................................................................... 27

8. Possible Format for Presenting Results of a Capture Zone Evaluation ............................................... 28

9. Examples of Summaries for Systematic Capture Zone Evaluations.................................................... 29

TABLE

1. Topics Associated with Cited References............................................................................................. 35

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FIGURES

1. Illustration of horizontal and vertical capture zones........................................................................... 1

2. Illustration of failed capture................................................................................................................ 2

3. Remedy objectives may or may not require complete hydraulic capture........................................... 7

4. Illustration of a Target Capture Zone.................................................................................................. 8

5. Interpreting capture from water level maps...................................................................................... 10

6. Drawdown and capture are not the same.......................................................................................... 12

7. Gradient vector map example........................................................................................................... 14

8. Issues associated with well inefficiency and well losses at pumping well....................................... 15

9. Water level interpretation with measurement at pumping well versus near pumping well.............. 16

10. Inward flow at boundary is hardest to achieve half-way between the pumping wells..................... 18

11. Complication associated with water level pairs................................................................................ 18

12. Cross-section schematic illustrating water level pairs...................................................................... 19

13. Estimated flow rate calculation......................................................................................................... 20

14. Capture zone width calculation, one extraction well........................................................................ 21

15. Types of downgradient monitoring wells......................................................................................... 25

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ACKNOWLEDGEMENTS

The U.S. EPA Office of Research and Development (ORD) wishes to express their appreciation to the 

U.S. EPA Ground Water Forum for their initial conception of the idea for this document and their helpful 

comments received during the writing. The Ground Water Forum was instrumental in the development 

and review of this document along with ORD scientists Mr. Steve Acree, Dr. David Burden, 

Dr. David Jewett, and Dr. Randall Ross.

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