Time domain electromagnetic survey for assisting in determining the groundwater resources on property located in the Kau District, Island of Hawaii

Abstract

"This report contains the procedures and results of a surface Time Domain Electromagnetic (TDEM) geophysical survey performed for groundwater resource evaluation on property located near Kahuku Ranch in the Kau District, Island of Hawaii. Zapata Incorporated, Blackhawk Division (Blackhawk) conducted the survey from August 5 through August 9, 2007 for Nani Kahuku Aina, LLC (NKA) located in Aiea, Hawaii. The main objective of the TDEM survey was to explore for high-level groundwater occurrences on property that NKA has gained access permission. The survey was conducted at five TDEM sites to help determine the optimum location for a future groundwater well located along Mainalahoa Highway (Hwy 11) near the junction of South Point Road. TDEM is a geophysical method that determines from the surface the geoelectric section (resistivity layering) of the subsurface. From the geoelectric section, information about geology and water quality can be inferred. This is possible because the electrical resistivity of the earth depends on lithology, porosity, the degree of saturation, and concentration of dissolved solids in the groundwater. Geophysical surveys, combined with other hydrogeologic information, are used to provide optimum locations for well placement and well completion depths."