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Soil sample analytical results for piping removal and UST removal are presented in Table 1 and Table 2, respectively. Following removal of the UST, approximately 371 tons of diesel fuel=impacted soil were removed from the site and disposed at the:,BFI Landfill;located in Livermore, California on March 23, 1999. The UST excavation was backfilled with clean soil imported to the site. Organic and inorganic analytical results for testing of backfill soil are presented in Table 2 and Table 3, respectively. A soil boring investigation by ATC, described in a reportentitled "Phase II Environmental Soil Investigation, AT&T'Microwave Relay Facility," dated April 6, 2000, involved drilling of 10 f ce (bgs) in the vicinity of the Geo robe borings to`.depths of 12 to 32 feet below ground sura { g ) ty p former UST. This investigation found that';-diesel impacted soil appears to be confined to the immediate vicinity of the former UST excavation in an area approximately 25 feet long by 25 feet wide, and in the:depth interval from '16 to 27 feet bgs.- A soil boring location map, including 1 a line depicting the limit of diesel fuel-impacted soil, is presented in Figure 4. Soil sampling analytical results are"presented in Table 4. Analytical results of groundwater samples from that investigation indicate that diesel fuel in the' groundwater migrated from the former UST excavation slightly to the south and east. The diesel fuel impacted groundwater appeared to be laterally confined to an area approximately 60 feet long by 35 feet wide. Diesel fuel was found in groundwater at a maximum reported concentration of 150 micrograms per liter (ug/L) adjacent to the UST excavation, and decreased to a concentration of 58 ug/L, 20 feet farther to the south. No BTEX or MTBE were detected in grab groundwater samples collected from the borings, with the exception of total xylenes detected in the grab sample from one boring at 1.2 ug/L. A map depicting the lateral extent of diesel fuel detected in the groundwater is presented in Figure 5. A soil cross section map is presented in Figure 6. Groundwater analytical results are presented in Table 5. A groundwater investigation by ATC is described in a .re ort entitled, "Report of Findings, Groundwater Monitoring Well Installation and!December 2000 Quarterly Monitoring, AT&T ` Microwave Relay Facility," dated January;; 19, 2001. In this investigation, three two-inch diameter groundwater monitoring wells were installed to a�depth of 38 feet bgs in the immediate vicinity of the former UST on December. 13, 2000. Groundwater was sampled quarterly from these wells beginning on December 18, 2000and ending on October 1, 2001. Reports of quarterly groundwater sampling were issued to the Public Health Services.San Joaquin County, Environmental Health Division (PHSSJC-EHD) `on January 19, 2001, May 4, 2001, September. a 28, 2001, and October 22, 2001. During this period, the direction of groundwater flow ranged from south to southwest with a gradient ;of approximately 0.004 foot/foot. No detected . concentrations of TPH-D were found in the ,groundwater except in the second quarter of sampling in well MW-3 (downgradient from the former UST) at a concentration of 150 ug/L. The locations of the wells and the groundwater;contours from the last quarter,of sampling are presented in Figure 7.- Depth to groundwater is presented in Table 6. Groundwater sampling- parameters amplingparameters are presented in Table 7. Groundwater analytical results are presented in Table 8. _ Groundwater monitoring uas discontinued following the four completed quarters of sampling. ATC Associates Inc, - 2 project No.53.75128.0001 i