About

The primary scientific objective of the Humuʻula Groundwater Research Project (HGRP) is to gain a better understanding of the groundwater resources available in the saddle region of the island of Hawaiʻi. In order to achieve this objective, two ~6000' holes will be drilled from the surface to the theoretical Ghyben-Herzberg freshwater lens that floats on top of denser seawater in island settings. The first hole will be drilled on the grounds of the Pōhakuloa Training Area (PTA), and the second hole will be drilled about 10 km away; it will also be on PTA land but in a location contingent on the findings of the first hole.
Each hole will recover a continuous stratigraphic sequence of subaerial shield-stage and post-shield-stage lava rock and ash samples, expected to be entirely from Mauna Kea Volcano. Processing, characterization and logging of the rock core will be adequate for future scientific work that may be done on the samples, with reports produced by the methods used for the Hawaiʻi Scientific Drilling Project (HSDP). Funding for the drilling and the initial characterization and logging of the core has been provided by the U.S. Army and the National Science Foundation.
In order to reach the projected depth of 6000' or more, the planned drilling program consists of first coring to a depth of 3000'-3500' using a PQ-sized (3.378” core diameter) bit. At that point, the drill pipe can be used as casing for open-hole drilling to the bottom of the hole with an HQ-sized (2.5” core diameter) bit. This plan will be repeated for the second hole as well, although the exact PQ to HQ transition is dependent on the downhole rock stability conditions.
During and after coring operations, the groundwater in the boreholes will be monitored and analyzed with respect to determining the viability of a long-term water well or wells that can meet the usage needs of PTA activities.