Results of exploratory drilling for water in Waihanau Valley, Moloka`i, Hawai`i
Takasaki KJ. 1986. Results of exploratory drilling for water in Waihanau Valley, Moloka`i, Hawai`i. U.S. Geological Survey (USGS) Water Resources Investigations Report. report 85-4332. United States Geological Survey. Honolulu, HI
Three exploratory wells, located in lower Waihanau Valley on Molokai, were drilled and tested for their yields during the period May to October 1983. The first well, 582 feet deep, tapped the main water body in a basaltic aquifer intruded by scattered near-parallel volcanic dikes. Analyses of the chemical constituents and trace metals of the water pumped indicated that it was of excellent quality. Based on these results, the well was finished as a production well. A shallow water body perched about 30 feet below ground surface and more than 400 feet above the main water body was discovered during the drilling of the first well. Two wells were-drilled to depths of 200 and 150 feet, respectively, to explore this perched water. Drilling logs and yield tests indicated that the perched aquifer is a thin, shallow partly confined deposit of poorly consolidated talus debris that underlies a more consolidated and less permeable deposit of alluvial and talus debris. The poorly permeable rocks that overlie the perched-water body act as the confining member. The underlying perching formation consists of highly weathered and poorly permeable basaltic lava flows that extend to a depth of about 200 feet. With depth, the basaltic lava flows become progressively less weathered, more permeable, and finally cease to be a perching layer. Due to the generally poor yield of the wells, no further attempt was made to develop the perched water body. Graphic logs of the wells and graphs of the yield tests conducted are included in this report.
- Type
- Published Report
- Authors
- Takasaki, Kiyoshi
- Date of Issue
- 1986
- Publisher
- United States Geological Survey
- Units
- KALA
- Keywords
- Aquatic Sciences, East Moloka`i Volcano HI, Groundwater, Hydrology (General), Kalaupapa Peninsula HI, Water Quality, Water Resources