: Geophysical tests comprised of surface refraction and borehole seismic tests were performed. Results from geotechnical in situ tests, which included standard, penetration and plate bearing tests, are also presented to provide a comprehensive report on the foundation materials. The elastic properties, Young's modulus, Poisson's ratio, shear modulus, and constrained modulus were determined as a function of depth for the foundation soils. These properties are necessary to design a stable foundation that will experience dynamic loading. Foundation materials encountered at this site were coral sands, silts, and gravels to a depth of 60 ft (el -52). The upper 14 ft of foundation soils are a hydraulically placed fill of beach sand. The materials are medium dense to dense sands. A global average SPT N sub 1 (60) value of 22 is appropriate for the site and correlates to a sand with a relative density of 65%. The shear modulus ranges from 77,000 psi. Poisson's ratio varies from 0.40 for unsaturated to 0.49 for saturated soil. A method was presented to estimate moduli under the expected load from present unloaded in situ moduli values using the K2 parameter. An estimate of the moduli for the expected foundation load was presented for the upper 30 ft of the foundation. A comparison of the plate bearing test and seismic derived Young's modulus shows good agreement, 123,000 psi and 78,000 psi, respectively. Radar tower foundations; Dynamic loads; Soil moduli.

: The U.S. Army Water Detection Response Team is designed to offer assistance to the military in securing water supplies in support of military operations. Currently, the team is staffed by volunteer civilians. However, plans are to transition field operations functions of the team to active or reserve military units. The Geophysics Element of the team develops and maintains capability to apply surface geophysical methods for location of well drilling sites. The Geophysics Element will be deployed only if existing data are insufficient to support assistance requests. The Geophysics Element is equipped to conduct and interpret seismic refraction, electrical resistivity, and very low frequency electromagnetic surveys for water well siting. The response team has assisted requesting major commands in Southwest Asia, Northeast Africa, Central American, and Korea. The Geophysics Element has been deployed to participate in several major military exercises. Case histories of the Geophysics Element involvement in these exercises are presented in this report. Keywords: Geophysical prospecting; Water wells/detection; Stratigraphy; Structural geology; Ground water; Electromagnetic wave reflections; Site selection/hydrology.

A microgravity survey consisting of 347 stations was conducted in the upstream switchyard of the Wilson Dam powerplant. The objective of the survey was the detection of subsurface cavities or other anomalous conditions that could threaten the integrity of the switchyard structures. Six anomalous areas were identified on the gravity anomaly map and ranked for their interpreted significance. From the results, nine boring locations were selected to investigate the cause of the anomalies. This report presents details of the field survey, data processing interpretations, and recommended drilling locations for subsurface investigation.