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Technical Memorandum on Surface Geophysical Surveys, High Priority SWMUs
Section 1 - Introduction
Several high priority Solid Waste Management Units (SWMUs) were identified at CSSA during an environmental assessment field survey performed by Parsons Engineering Science, Inc. (Parsons ES), in 1992. The following eight priority SWMUs were chosen as part of this study: B-7, B-8, B-11, B-12, B-15/16, B-22, B-23 and B-23A, and B-24 (Figure 1.1). Some of the SWMUs were selected for investigation based on their proximity to CSSA monitoring well 16, the focus of an ongoing groundwater investigation. Others were selected based on the preliminary field survey or waste records for that site. A surface geophysical investigation was conducted at each of these SWMUs to determine the nature and extent of potential subsurface disturbance (anomalies). This work was performed under Armstrong Laboratory/OEB Contract F33615-89-D-4003, order 126.
Geophysical methods included electromagnetic induction (EM) and, in some cases, ground-penetrating radar (GPR). The EM surveys were performed using an EM-31 Geonics instrument, and the GPR surveys were performed using the Pulse EKKO IV system. A grid was established at each SWMU where EM readings were collected at specified intervals, commonly in the north-south and/or east-west directions. The readings were subsequently contoured using the Surfer computer-based program. GPR transects were conducted in some of the areas identified as EM anomalies.