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Groundwater chemistry in the vicinity of the Puna Geothermal Venture Power Plant, Hawai‘i, after two decades of production

Scientific Investigations Report 2015-5139
By: , , , , and 
https://doi.org/10.3133/sir20155139

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Abstract

We report chemical data for selected shallow wells and coastal springs that were sampled in 2014 to determine whether geothermal power production in the Puna area over the past two decades has affected the characteristics of regional groundwater. The samples were analyzed for major and minor chemical species, trace metals of environmental concern, stable isotopes of water, and two organic compounds (pentane and isopropanol) that are injected into the deep geothermal reservoir at the power plant. Isopropanol was not detected in any of the groundwaters; confirmed detection of pentane was restricted to one monitoring well near the power plant at a low concentration not indicative of source. Thus, neither organic compound linked geothermal operations to groundwater contamination, though chemical stability and transport velocity questions exist for both tracers. Based on our chemical analysis of geothermal fluid at the power plant and on many similar results from commercially analyzed samples, we could not show that geothermal constituents in the groundwaters we sampled came from the commercially developed reservoir. Our data are consistent with a long-held view that heat moves by conduction from the geothermal reservoir into shallow groundwaters through a zone of low permeability rock that blocks passage of geothermal water. The data do not rule out all impacts of geothermal production on groundwater. Removal of heat during production, for example, may be responsible for minor changes that have occurred in some groundwater over time, such as the decline in temperature of one monitoring well near the power plant. Such indirect impacts are much harder to assess, but point out the need for an ongoing groundwater monitoring program that should include the coastal springs down-gradient from the power plant.

Suggested Citation

Evans, W.C., Bergfeld, D., Sutton, A.J., Lee, R.C., and Lorenson, T.D., 2015, Groundwater chemistry in the vicinity of the Puna Geothermal Venture power plant, Hawai‘i, after two decades of production: U.S. Geological Survey Scientific Investigations Report 2015-5139, 26 p., http://dx.doi.org/10.3133/sir20155139.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Geothermal Development and Operations
  • Methods 
  • Results
  • Injectate Composition Over Time
  • Groundwater Chemistry
  • Conclusions
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Groundwater chemistry in the vicinity of the Puna Geothermal Venture Power Plant, Hawai‘i, after two decades of production
Series title Scientific Investigations Report
Series number 2015-5139
DOI 10.3133/sir20155139
Year Published 2015
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) National Research Program - Western Branch
Description v, 26 p.
Time Range Start 2014-01-01
Time Range End 2014-12-31
Country United States
State Hawaii
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details