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Technical Memorandum on Surface Geophysical Surveys, High Priority SWMUs
Section 9 - SWMU B-24
9.1 - Site History and Description
SWMU B-24 is located in the north pasture approximately 500 feet north of SWMU B-7 (Figure 1.1). Several large cedar piles were cleared from the site in order to perform the EM survey. The ground surface was scraped in places from clearing operations. B-24 is bounded by a gravel road to the east and north, and a dry pond and trees to the west (Figure 9.1). Spent ammunition and small rockets were observed at this site during the initial field survey.
9.2 - Geophysical Survey Results
A grid was established at SWMU B-24 by placing wooden stakes at 50-foot intervals. The EM survey was conducted at 25-foot intervals along north-south transects. The EM conductivity and in-phase contour maps are shown on Figure 9.2 and Figure 9.3. Three EM anomalies, identified as A, B, and C on Figure 9.4, were observed from conductivity and in-phase data at B-24. These isolated anomalies indicate potential areas of subsurface disturbance such as buried waste material. Anomaly B is more prevalent on the in-phase data (Figure 9.3), which suggests the presence of buried metal debris in this area.
Three GPR transects were conducted at B-24, one across each anomaly discussed above. The results of the GPR transect at anomaly B is shown on Figure 9.5. The location of the GPR transect is shown on Figure 9.4. Broken reflectors were observed on this GPR profile in the same area of high conductivity and in-phase EM readings. The GPR survey provided an indication of potential subsurface disturbance at anomaly B.
In summary, three isolated anomalies were inferred at SWMU B-24 by EM and GPR methods. These anomalies, identified as A, B, and C on Figure 9.4, indicate potential areas of subsurface disturbance.