Application of Surface Geophysics for Providing a Detailed Geotechnical Assessment of a Large Resort Development Site in Anguilla, BWI

Ocean Earth Technologies, Inc. (OET), a subsidiary of N.S. Nettles &Associates, Inc., was contracted to perform a geophysical mapping study andcomprehensive geotechnical investigation of a proposed resort property located inRendezvous Bay, Anguilla, British West Indies (BWI) (Figure 1). The purpose of themapping was to provide extensive detail into the geologic conditions across the siteand in the bay that would help to identify any anomalous subsurface features, such assolution zones or fractures in the limestone unit, which would be potential hazardsand areas of concern for construction purposes. Additionally, the testing was used toidentify the depth to competent rock across the site, the thicknesses of overlyingunconsolidated units, and ideal drilling locations for the placement of flushingchannels that will connect the inland salt pond on the resort property to RendezvousBay. The geophysical surveys consisted of both Multi-Electrode ElectricalResistivity (MER) testing, as well as Multi-Channel Analysis of Surface Waves(MASW), a seismic method of geophysical mapping (Nettles, 2005; Ocean EarthTechnologies, 2006; Ocean Earth Technologies, 2006). These surveys were followedby 45 Standard Penetration Test (SPT) borings and 60 ten foot long, four inch rockcore borings in order to ground-truth the geophysical data and obtain physicalsamples for laboratory analysis of engineering properties for design purposes.Additionally, 71 Cone Penetration Test (CPT) soundings were also performed on thebeach front unconsolidated sands.