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Appendix C Ground Penetrating Radar Investigation Phase ii ESA Multi-Modal Station`Six-Block ProjeX January 6 2003 Page 7 of 9 IDconcrete patch area near the center of this portion of the property includes several possible current or former UST locations Radargrams 41 and 42 each show one possible current or former UST location and Radargram 43 shows two possible current or former UST locations The surface patchwork suggests that if USTs were located in this area, they were most likely previously removed and the UST-like reflections, if not responses to actual USTs, may be the result of backfilling of UST-shaped spaces with non-native fill after removal Radargrams 44 and 45 display the discrepant nature of the soil beneath the patch in comparison to the presumably native soil present at the rest of the property Three additional possible USTs beyond the limits of the large concrete patch were also identified during the GPR investigation Two possible USTs are shown north of the center of this portion of the property in Radargram 46 and one possible UST near the southwest corner of this portion of the property is depicted in Radargram 47 The collected GPR data for this portion of the property also indicate the presence of rebar in both the original concrete at the property and the concrete patch 701 E Weber Avenue A total of 67 GPR Ines were walked on August 29, 2002, to investigate six potential boring locations in the parking area of the property located at 701 E Weber Avenue Each of the boring locations was investigated by nine to 12 lines spaced three to five feet apart and arranged in a gnd pattern Radargram 48 shows a typical data line with no features of concern However, Radargram 49 demonstrates that portions of the property are characterized by highly disturbed subsurface conditions Boring locations in each of the six investigated areas were identified to avoid potential buried objects 729 E Weber Avenue On August 29, 2002, 18 GPR lines were walked in the accessible areas of 729 E Weber Avenue This . property is currently a tire shop with tire racks located along the eastern and western portions of the parcel A small structure housing an office and a shop is located at the rear of the property The accessible portion of the property was thus limited to an approximately 17-foot by 65-foot area from the front gate to the structure between the tire racks This area was investigated to identify potential boring locations Radargram 50 shows a near-surface reflection hyperbola typical of a buried pipe A deeper buried feature is shown in Radargram 51 The absence of this feature in data collected from adjacent GPR lines suggests that it is not an object of significant length It may be associated with the nearby drain at the property Most of the remaining area of the property investigated appears to have disturbed subsurface conditions 1.38 Black 5 820 E Channel Street The property located at 820 E Channel Street was investigated by 32 GPR lines on August 30, 2002 Much of the property was occupied by equipment, automotive parts, and containers among other miscellaneous items, and only accessible portions of the property, consisting of three distinct areas, were investigated Radargram 52 shows a typical GPR data line collected from the northern portion of the property Rebar is evident in the concrete slab covering the property and a single, distinct buried object is shown A perpendicular GPR line walked over the location of this reflection hyperbola confirmed the presence of an object at this location, but adjacent GPR lines indicated that the object did not extend laterally beyond a limited area A typical data line from the southern portion of the property, again indicating the presence of rebar, is shown in Radargram 53 836 E Channel Street and 147 N Aurora Street The property located at 836 E Channel Street comprises two parcels and was investigated by 12 GPR lines on May 17, 2002 to clear two potential boring locations for drilling Only small-scale anomalies were identified and the actual boring locations were selected to avoid these possible buried objects A