Time domain electromagnetic surveys for assisting in determining the groundwater resources on Greenwell Farms property, Island of Hawaii

Abstract

"This report contains the procedures and results of surface Time Domain Electromagnetic (TDEM) geophysical surveys performed for groundwater resource evaluation on Greenwell Farms property located on the Island of Hawaii. ZAPATA ENGINEERING Blackhawk Division (Blackhawk) conducted the surveys on February 2, 2007 for Pa’ahana Enterprises LLC (PEL) of Kealakekua, Hawaii and Greenwell Farms (GF) of Kealakekua, Hawaii. The main objective of the TDEM surveys was to explore for groundwater occurrences located on GF property near the Greenwell Farms Coffee Plantation. The surveys were conducted at two TDEM sites to help determine the optimum location for a future groundwater well below the Mamalahoa Highway in Kealakekua, Hawaii. TDEM is a geophysical method that determines from 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, 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 water well placement and well completion depths."