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2.3 Ground Penetrating Radar Survey A ground penetrating radar (GPR) survey of the Barker property was completed in conjunction with the site inspection on January 27, 2009. The purpose of the GPR survey was to evaluate the lateral continuity of the soil layers across the property. Anomalous variations in the subsurface, if present, could be related to hidden geologic features of interest in our investigation. The survey was performed by BCI personnel and consisted of a grid of 20 exterior transects and one exterior /interior transect scanned over portions of the site at the locations shown on Figure 3. A summary report on the GPR survey is included in Appendix B. Inspection of the GPR transect profiles indicates the depth of penetration of the radar signal ranged from 11 to 13 feet below grade for the transects completed utilizing the 250 MHz antenna. On many of the profiles, a series of moderate intensity, continuous, parallel to subparallel, horizontal, and sinuous reflection events was identified between estimated depths of 1 and 5 feet below the ground surface. The reflections are interpreted to represent shallow soil layering within the surficial sandy soils. On most of the profiles, a moderate to strong intensity, continuous, generally horizontal, and sinuous reflective horizon was identified between estimated depths of 5 and 8 feet below the ground surface. The reflective horizon correlates with the upper surface of a clayey subsurface soil layer encountered in the hand auger borings. Shallow hyperbolic reflectors (< 3 feet) were present on many of the transect profiles and probably represent areas with shallow pipes, tree roots, and/or utility lines (Figure 3). Multiple series of prominent hyperbolic reflections were identified in the east and west yard areas, and likely represent underground utility lines or pipes (Figure 3). No anomalies suggestive of obvious subsurface karst or sinkhole features were identified in the GPR survey. No downwarping of reflective layers or areas of deeper signal penetration were identified on the profiles. 2.4 Hand Auger Borings and Test Pit Excavations Four shallow hand auger borings, HA -1 to HA -4, were completed during the site inspection, at the locations shown on Figure 2. Boring HA -1 was located along the west side of the house, boring HA -2 was located along the south wall of the house, boring HA -3 was located near the southeast corner of the house, and boring HA -4 was located along the north wall of the house. All borings were advanced to a depth of 7 feet below grade. In general, the borings encountered a similar soil sequence consisting of variably colored fine- grained quartz sand extending from the ground surface to depths ranging from 5 to 6'/2 feet below grade. Below the surficial sands a layer of variably clayey fine- grained quartz sand was encountered to the boring termination depths. The water table was not encountered in the borings. Soil boring logs are included in Appendix C. Two shallow test pit excavations, TP -1 and TP -2, were completed in order to examine the type and condition of the house foundation and screened porch slab. The locations of the test pits are shown on Figure 2. Test pit TP -1 was located along the east wall of the house and was excavated to a depth of 23 inches below grade. Test pit TP -2 was located along the north edge of the screened porch and was excavated to a depth of 9 inches below grade. Based on observations and measurements made within the test pit, the foundation for the house consists of a stem wall supported on a continuous strip footing embedded at a depth of approximately 18 inches below existing grade. The screened porch slab consists of a concrete slab -on- grade. Hand cone penetrometer probes completed in the test pits indicate the house foundation bears on very loose to medium dense soils (Appendix C). Subsidence Investigation BCI Project No.: 19 -17094 Barker Residence March 2009 Claim No.: 3428 Page 3