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Results of exploratory drilling for water in Waihanau Valley, Molokai, Hawaii

January 1, 1994

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 ft deep, tapped the main water body in a basaltic aquifer intruded by scattered near-parallel volcanic dikes. Water in this water body is impounded by the dikes and has a head of about nine feet above sea level. A 48-hour pumping test was conducted on this well. The well was pumped at various rates ranging from 144 to 455 gal/min for nine hours. Thereafter, the well was pumped for 39 hours at a rate of 156 gal/min approximating the planned operational rate of 150 gal/min. The specific capacities of the well at the rates pumped averaged about 30 gal/min/ft of drawdown. The temperature of the pumped water remained nearly constant at 69 F (20.5 C). The chloride concentration ranged from 19 to 22 mg/L during the test. 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 ft below ground surface and more than 400 ft above the main water body was discovered during the drilling of the first well when about 50 gal/min of water cascaded down the well. Two wells were drilled to depths of 200 and 150 ft, respectively, to explore this perched water. The yields obtained from this perched water body were low and indicated that its development was not feasible. (Author 's abstract)

Citation Information

Publication Year 1986
Title Results of exploratory drilling for water in Waihanau Valley, Molokai, Hawaii
DOI 10.3133/wri854332
Authors K. J. Takasaki
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Water-Resources Investigations Report
Series Number 85-4332
Index ID wri854332
Record Source USGS Publications Warehouse