Georgia Water Science Center
This Web-only publication is available online in pdf format (3 MB): USGS OFR 2008-1349 (
)
Owen G. Holloway and Jonathan P. Waddell
U.S. Geological Survey Open-File Report 2008-1349, 24 pages (Published December 2008)
Prepared in cooperation with the U.S. Air Force, Aeronautical System Center
A borehole straddle packer was developed and tested by the U.S. Geological Survey to characterize the vertical distribution of contaminants, head, and hydraulic properties in open-borehole wells as part of an ongoing investigation of ground-water contamination at U.S. Air Force Plant 6 (AFP6) in Marietta, Georgia. To better understand contaminant fate and transport in a crystalline bedrock setting and to support remedial activities at AFP6, numerous wells have been constructed that include long open-hole intervals in the crystalline
bedrock. These wells can include several discontinuities that produce water, which may contain contaminants. Because of the complexity of ground-water flow and contaminant movement in the crystalline bedrock, it is important to characterize the hydraulic and water-quality characteristics of discrete intervals in these wells. The straddle packer facilitates ground-water sampling and hydraulic testing of discrete intervals, and delivery of fluids including tracer suites and remedial agents into these discontinuities.
The straddle packer consists of two inflatable packers, a dual-pump system, a pressure-sensing system, and an aqueous injection system. Tests were conducted to assess the accuracy of the pressure-sensing systems, and water samples were collected for analysis of volatile organic compound (VOCs) concentrations. Pressure-transducer readings matched computed water-column height, with a coefficient of determination of greater than 0.99. The straddle packer incorporates both an air-driven piston pump and a variable-frequency, electronic, submersible pump. Only slight differences were observed between VOC concentrations in samples collected using the two different types of sampling pumps during two sampling events in July and August 2005. A test conducted to assess the effect of stagnation on VOC concentrations in water trapped in the system’s pump-tubing reel showed that concentrations were not affected. A comparison was conducted to assess differences between three water-sampling methods—collecting samples from the well by pumping a packer-isolated zone using a submersible pump, by using a grab sampler, and by using a passive diffusion sampler. Concentrations of tetrachloroethylene, trichloroethylene and 1,2-dichloropropane were greatest for samples collected using the submersible pump in the packed-isolated interval, suggesting that the straddle packer yielded the least dilute sample.
Abstract
Introduction
Purpose and Scope
Description of Study Area
Method of Study
Straddle-Packer Design
Early Straddle Packers
Design of AFP6 Straddle-Packer Systems
Water-Quality Trailer
Tubing and Cable Reel Assembly and Trailer
Inflatable Packers
Dual-Pump System
Pressure-Sensing System
Aqueous Injection System
AFP6 Straddle-Packer Operation
Deployment of Straddle Packer
Isolation of Interval
Interval Purging and Ground-Water Sample Collection
Testing of Hydraulic Properties
Decontamination of Straddle Packer
Assessment of Straddle-Packer Performance
Pressure Sensing System
Dual-Pump System
Effect of Tubing Reel on Ground-Water Sample Collection
Sampling Method Comparison
Summary
Acknowledgments
Selected References
Suggested citation:
Holloway, O.G., and Waddell, J.P., 2008, Design and operation of a borehole straddle packer for ground-water
sampling and hydraulic testing of discrete intervals at U.S. Air Force Plant 6, Marietta, Georgia: U.S. Geological
Survey Open-File Report 2008–1349, 24 p., Web-only publication available at https://pubs.usgs.gov/of/2008/1349/
This Web-only publication is available online in pdf format (3 MB): USGS OFR 2008-1349 ()
To view the PDF document, you need the Adobe Acrobat® Reader installed on your computer. (A free copy of the Acrobat® Reader may be downloaded from Adobe Systems Incorporated.)
Recent USGS publications for Georgia or Georgia Water-Resources Information
For more information, please contact webmaster-ga@usgs.gov.
U.S. Department of the Interior |
U.S. Geological Survey
URL: https://pubsdata.usgs.gov/pubs/of/2008/1349/index.html
Page Contact Information: Publications Team
Page Last Modified: Wednesday, 07-Dec-2016 21:37:10 EST
