Core photos, Hole 2 (KMA-1), Humu‘ula Groundwater Research Project

Date
2016
Authors
Thomas, Donald M.
Lautze, Nicole C.
Haskins, Eric
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Publisher
University of Hawaii at Manoa
Hawaii Groundwater and Geothermal Resources Center
Humu‘ula Groundwater Research Project
Abstract
Also known as “PTA” or “Saddle Road Project,” the Humuʻula Groundwater Research Project (HGRP) aimed to research the groundwater resources in the Hawaiʻi Island ‘Saddle’ region between Mauna Loa and Mauna Kea volcanoes by drilling two test holes on Army Garrison Hawaii land. Results include the discovery of: i) groundwater at a much shallower depth than expected, ii) a dike-impounded aquifer, and iii) a potential geothermal reservoir. By using the diamond wireline core drilling technology, we collected a continuous sequence of rock core. We documented our progress in a blog and made a complete stratigraphic record of the region. This continuous stratigraphic sequence contained subaerial shield-stage and post-shield-stage lava rock and ash samples from the Mauna Kea Volcano, documenting the area’s environmental, geologic, hydrologic, and thermal history.
Description
To measure the extent of the regional table found by the first hole, we drilled a second test hole approximately 10 kilometers west of the PTA-2 borehole. Within the top ~1,500 meters the hole did not encounter the regional aquifer, but found a sequence of confined, pressurized aquifers from ~300 meters below the ground surface. Layers of soil, ash, or explosive eruptive deposits confined these aquifers as highly pressurized water trapped between impermeable layers. Hence, as we drilled into the aquifers, water came spouting from the point of entry to up the drill string to several hundred to several thousand feet.
Keywords
core logging, core samples, Hawaii--Mauna Kea, Hawaii--Mauna Loa (Hawaii Island), Humuʻula Groundwater Research Project, Drill cores, well logging, Water Table, Groundwater, Groundwater flow
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