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rJ ' . 10 September 1996 AGE-NC Project No. 95-0106 Page 2 of 8 79.2 ppm,respectively. TPH-g, benzene, toluene and xylenes were detected in the water sample at concentrations of 117,000 parts per billion (ppb, reported as micrograms per liter), 10,100 ppb, 11,300 ppb and 9,330 ppb, respectively. 2.3. EXCAVATION OF UNDERGROUND STORAGE TANK AREA The former UST area was excavated in August 1995 to remove remaining impacted soil. Excavation procedures were supervised by representatives of AGE. Hydrocarbon-impacted soil was excavated to a depth of 8 feet below surface grade(bsg). The approximate limits of the August 1995 excavation are indicated on Figure 2. Approximately 100 cubic yards of impacted soil was removed from the former UST area. Petroleum hydrocarbons were not detected in soil samples collected from the floor of the excavation. Excavated soil was stockpiled adjacent to the excavation. . 2.4. GROUND WATER DEPTH AND GRADIENT Information obtained from nearby monitoring wells in Tracy indicates that the depth to ground water at the site is between 6 and 10 feet bsg; ground water in the August 1995 excavation was encountered at a depth of approximately 7 to 8 feet bsg. Ground water flow direction in the Tracy area is generally toward the north. 3.0. PROCEDURES 3.1. SOIL PROBE BORINGS 3.1.1. PROBING AND SAMPLING Six soil probe borings were advanced at the site on 20 December 1996. Figure 2 depicts the locations of the probe borings. The probe borings were advanced using AGE's van-mounted Geoprobe 5400 soil probing machine. Probe Borings P 1 and P2 were advanced east and south, respectively, of the former UST excavation. Probe Boring P3 (Probing P3) was placed on the south side of the dwelling on-site. Probing P4 was advanced on the northwest corner of the site. Probing P5 was advanced west of the former UST over excavation. Probing P6 was advanced in the driveway of the site.