Technical Memorandum Report No. 16
Preliminary Evaluation of Ground-Water Exploration Boreholes Near Pahala, Hawaii
Frank L. Peterson
January 1969
Introduction
Recent study of the anomalously high ground-water configuration near Pahala, Hawaii using electrical resistivity soundings (Hussong and Cox, 1967) has been, in part, the guide for an exploratory test drilling program conducted by C. Brewer & Company. In the area of the electrical resistivity study, two 3-inch test holes have been drilled to obtain water-level and water-quality information, and cored to obtain rock porosity and permeability information. Boring #1 was drilled at 123.34 feet above sea level and is located approximately 75 feet makai (seaward) of the FAP Highway 11 in Ninole Gulch near the town of Punaluu. Boring #2 was drilled 56.21 feet above sea level and is located at the site of resistivity sounding S-8 in the above-cited resistivity study of Hussong and Cox also near the town of Punaluu. Boring #1 was drilled to a depth of 174 feet (50.66 feet below sea level), and the static water level varied from 3.69 to 4.39 feet above sea level. Boring #2 was drilled to a depth of 90 feet (33.79 feet below sea level), and the static water level was 26.11 feet above sea level. Owing to seeming uncertainty of the reported static water level in Boring #2, it is urged that the water level be re-measured by first completely bailing the hole and then letting it stand for several hours, or better yet overnight, before measuring the water level, Electrical resistivity data obtained from sounding S-8, at the site of Boring #2, indicated that fresh water could be expected to occur at least 18 feet above sea level. Electrical resistivity information generally is lacking at the location of Boring #1. However, data from sounding S-13, approximately 1 mile away and approximately midway between the two test borings indicated a more normal water table of approximately 2 feet above sea level.