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Appendix C Ground Penetrating Radar Investigation Phase II ESA Multi-Modal Station"Six-Block Project" January 6,2003 Page 5 of 9 . An approximately three-foot by three-foot circular depression was noted at the property and an adjacent area was investigated None of the radargrams collected in the vicinity of the depression contained features of interest 822, 830, 840, and 848 E Miner Avenue, and 227 N Aurora Street The properties comprising the northeast comer of Block 2 were investigated on May 22 and 29, 2002 using 54 GPR Imes Nine potential locations for seven bonngs were selected Radargrams 17, 18, and 19, collected from 822, 830, and 840 E Miner Avenue, respectively, are characterized by strong radar signal attenuation with depth, suggesting a significant clay-rich soil layer is located in the area along E Miner Avenue A buried object clearly evident in Radargram 19 was avoided during final boring location selection Possible buried objects in Radargrams 17 and 18 were also identified and avoided Radargrams 20 and 21, from 848 E Miner Avenue and 227 N Aurora Street, respectively, depict relatively undisturbed areas of the subsurface of the northeast corner of Block 2 210 N Grant Street On May 14, 2002, 28 GPR lines were walked in the parking area of 210 N Grant Street to investigate this portion of the property for possible buried tanks or other items of concern Radargrams 22 and 23 show cross-sections of an observed asphalt patch including and collinear with several sewer vault covers Both radargrams depict disturbed subsurface conditions in the vicinity of the asphalt patch Several buried objects, Including a possible large-diameter pipe in association with the sewer system, are indicated in Radargram 23 An additional 36 lines were walked at the property to investigate six potential locations for five bonngs One potential boring location was located inside the warehouse on the eastern portion of the property and was eliminated due to limited access The other five potential locations were found to be . feasible locations for borings 13.6 Block 3 920 and 930 E Miner Avenue, and 911 E Channel Street The Block 3 properties were investigated by a total of 107 GPR lines on May 15, 2002 The properties at 920 and 930 E Miner Avenue were extensively investigated to obtain data relating to areas of potential concern identified during concurrent fieldwork These areas were primarily identified by slumping and patching of the asphalt and concrete at the properties Radargram 24 shows a typical line at 920 E Miner Avenue with a possible vertical conduit The uniform subsurface area in the upper portion of Radargram 24 is also evident in Radargrams 25 and 26 from. 930 E Miner Avenue, indicating that this is likely a native subsurface feature, not an anomaly such as an area of fill Radargram 25 shows a bounded disturbance that may be indicative of an area of fill in association with asphalt patching A line walked over a concrete patch inside the building at 930 E Miner Avenue is shown in Radargram 26 The patch is identified by the lack of rebar, and the area beneath the patch is bounded and is significantly different than the adjacent subsurface, again suggesting an area of fill Radargram 27 is a representative line from inside the warehouse at 911 E Channel Street, showing a tight rebar pattern in the concrete pad Seven potential boring locations at Block 3 were identified and investigated by GPR, as well Review of the data indicated that there were no identified features warranting relocation of any of the potential bonng locations