A seismic refraction investigation of a glacial outwash aquifer in southwestern, New Brunswick

Abstract

The purpose of this project was to conduct an initial geophysical survey of the Utopia Delta outwash aquifer using modern seismic refraction methods. The results of the seismic refraction survey are to aid in the ongoing groundwater investigation conducted by the University of New Brunswick Groundwater Studies Group. Overall it was found that the 11.16-Kg weight drop was the most practical seismic source for the Utopia Delta seismic refraction survey considering energy output and field time requirements. Site conditions were beneficial for the use of the 11.16-Kg weight drop because of excellent on-site vehicle access. It was observed that the 12-gauge Buffalo gun has the highest amount of overall energy output including high frequency energy in the 83.3 Hz range. The depth section for Array A revealed an undulating bedrock topology with bedrock depth varying between 16.6 and 21.8 metres. The water table was mapped at a depth ranging from 7.7 to 8.9 metres. This range correlates well with average water levels for October taken at MW-3, located 200 meters west, of approximately 8 metres below ground (Reeves and MacQuarrie, 1997). Results from the velocity analysis for array A indicate refractor velocities for the saturated sand and gravel layer ranging from 2198 m/sec to 3279 m/sec. These values are generally acceptable for water saturated sand (Kearey and Brooks, 1991). The lack of quality data for arrays B and C due to windy conditions seriously affected the interpretation of these sections. In addition, the phantoming technique was not implemented, and therefore, refractor coverage was minimal.