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I December 1995 <br /> AGE-NC Project No. 9:5-0106 <br /> Page 2 of 5 <br /> 2.3. RE-EXCAVATION OF UST AREA <br /> In an attempt to remove remaining impacted soil, the former UST area was re-excavated in August <br /> 1995 by AGE. Hydrocarbon-impacted soil was excavated to a depth of 8 feet. Excavation was <br /> performed using a backhoe. Approximate limits of the August 1995 excavation are indicated on <br /> Figure 2. <br /> Five soil samples were collected from the excavation and submitted to a laboratory for analysis. <br /> Petroleum hydrocarbons were detected in samples from each sidewall. No hydrocarbons were <br /> detected in the sample collected from the floor of the excavation. <br /> Approximately 100 cubic yards of impacted soil was removed from the former UST area. The soil <br /> was stockpiled adjacent to the excavation. Petroleum hydrocarbons were detected in stockpile soil <br /> samples at concentrations up to 440 ppm. <br /> 2.4. GROUND WATER DEPTH AND GRADIENT <br /> Information obtained from nearby monitoring wells in Tracy indicate that groundwater depth at the <br /> site is between 8 to 10 feet. Groundwater flow direction in the Tracy area is generally to the north. <br /> 3.0. SCOPE OF WORK <br /> 3.1. PROBING AND SAMPLING <br /> A subsurface investigation of the site is necessary to determine the lateral and vertical extent of <br /> hydrocarbon-impacted soil and ground water. AGE proposes to advance at least six soil <br /> borings/probings at the site to determine the extent of impacted soil and ground water. Probings will <br /> be advanced to depths of approximately 15 feet (below ground water), using direct push technology <br /> (DPT). <br /> Probings will be advanced around the former UST excavation and at the property boundaries of the <br /> site using a Geoprobe 5400 probing unit. Proposed probing locations are illustrated in Figure 2. <br /> Soil samples will be collected at depths of 5, 10 and 15 feet below surface grade (bsg) using a <br /> Geoprobe sampler and four brass sleeves. Upon sample retrieval, the second brass sleeve will be <br /> removed from the sampler. The ends of the sleeve will be immediately covered with Teflon tape or <br /> aluminum sheets, capped and sealed with tape. Each sample will be placed in a chilled container for <br /> transportation to a State-certified laboratory. Each sample sleeve will be labeled with the following: <br /> boring location, depth, time, date and sampler's initials. <br />