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6 concentration was observed in the southwest corner of the Site in Boring E3-1 at 10 feet bgs. TPH as diesel (TPH-d) was detected in 20 samples at concentrations ranging from 5.0 to 9,200 mg/kg. TPH as motor oil (TPH-mo) was detected in 16 of the 71 samples collected. Similar to TPH-g, the highest concentrations of TPH-d and TPH-mo were observed in Boring E3-1 at 10 feet bgs; however, the sample collected from 15 feet bgs in this boring was non-detect for all TPH constituents. Vertical delineation of TPH impacts has been achieved across the Site; however,lateral delineation of TPH impacts in Boring E3-1 have not been delineated. Of the 17 metals in the Title 22 Metals suite, 13 had concentrations greater than laboratory RLs. The remaining four constituents (antimony, molybdenum, silver and thallium) had no detectable concentrations. The typical metals that occur on MGP sites include arsenic and lead with lesser observances of mercury. Arsenic and lead were observed in all samples collected at the Site. Arsenic concentrations ranged from 1.27 to 12.6 mg/kg and lead concentrations ranged from 2.19 to 41.3 mg/kg. Mercury was detected in only one sample at a concentration of 1.0 mg/kg. It should be noted that the detections of the Title 22 Metals at the Site appear to be similar to background concentrations observed in samples collected from the surrounding area. As previously mentioned, I1 soil samples were analyzed for VOCs. The highest detections of VOCs in soil were observed at the northwest corner of the Site where a gasoline UST was previously located. As anticipated, VOCs detected in Grid A3 were primarily those associated with the gasoline UST and include the following: benzene; toluene; ethylbenzene; xylenes; trimethylbenzenes; and butyl-, isopropyl-, and propyl-benzenes. In addition, other detected constituents included 2-butanone, acetone and naphthalene. The highest concentrations of these constituents were observed in Boring A3-2A. Select analytical data results from soil samples collected during the RI investigation are shown in Figure 3. Soil Gas: A total of 17 soil gas samples (including two duplicates) were analyzed for VOCs using EPA Method TO-15 (including naphthalene), with additional analyses for isobutane, the leak-detection compound utilized on-site. A total of 25 individual VOCs were detected in the samples collected. The highest concentrations detected for VOCs in soil gas were found in Soil Gas Boring A3-SGI, which was installed in the northwest comer of the Site in the vicinity of a former UST that has been removed. The highest concentrations appear to relate to a release from the former UST and include 1,2,4-trimethylbenzene [230,000 micrograms per cubic meter (ug/m3)] and m,p-xylenes (180,000 ug/m3). In addition, a tetrachloroethene (PCE) detection in Soil Gas Boring Al-SG1 exceeded the California Human Health Screening Level of 603 micrograms per kilogram(ug/m). Select analytical data results from soil gas samples collected during the RI investigation are shown in Figure 4. Groundwater: During the RI investigation, six groundwater samples, including one duplicate, were collected from the five groundwater monitoring wells in the well network at the Site(TW-1 through TW-5) and analyzed for PAHs, TPH, Title 22 Metals and VOCs. All groundwater impacts identified during the RI investigation were found in well TW-5,which is located directly adjacent to the former gasoline UST. The only detection of PAHs in groundwater was naphthalene at a concentration of 6.0 micrograms per liter(ug/L)in Monitoring Well TW-5. TPH-g and TPH-d were reported in Monitoring Well TW-5 at maximum concentrations of 290 and 350 ug/L,respectively. There were no detections of TPH-mo.