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Mr. Wayne Dietz July 14, 2008 2154 S. El Dorado Street Investors, a California Limited Partnership Page 5 of 8 The final groundwater ESL for sites that threaten drinking water resources reflects the lowest screening level for drinking water toxicity, aquatic habitat protection (discharges to surface water), indoor-air impacts (volatile chemicals only), and a ceiling level for tastes and odors or other nuisance concerns (Table F-la). The final groundwater ESL for sites where drinking water resources are not a concern (Table F-lb) reflects the lower of screening levels for the same set of environmental concerns, with the exception of the drinking water component and an alternative ceiling level. At this stage of the investigation, ROKEN has determined that the ESLs listed in Table F-lb(groundwater is not a current or potential drinking water source) is the most appropriate for the evaluation of groundwater conditions at the site. INVESTIGATION RESULTS Soil encountered during this investigation generally consisted of several feet of fill, reddish brown silty sand and sandy clay with some interbedded graded sand to approximately 25 to 30 feet bgs, and greenish brown, silty and sandy clay below to depths of approximately 45 feet bgs. The water level in temporary well casings was measured at approximately 26 feet bgs. The PID detected organic vapors in temporary well casings at GW-6 (337 ppm), GW-7 (38 ppm) and GW-8 (280 ppm). Petroleum hydrocarbon odors were noted in soil from boring at sample locations GW -2 and GW-6 through GW-10. Various Extractable petroleum hydrocarbons, metals, VOCs and SVOCs were detected in groundwater samples collected at the site during this investigation. For QA/QC purposes a duplicate sample (GW-11) was collected at GW-6 and the analytical results reported for GW-6 and its duplicate are very similar and within acceptable range. No detected analytes were reported for the Trip Blank. The results of the groundwater sample analyses are presented in TABLE 1. Laboratory reports are attached in APPENDIX B. ROKEN reviewed the groundwater analytical results and compared the results to ESLs. The findings of this review are summarized as follows: EPA Method 8015 Diesel Range Organics(DRO)and Motor Oil Range Organics (MORO) A very low concentration of MORO was detected in groundwater at sample location GW-1. MORO was not detected above the laboratory reporting limit in groundwater collected from the other nine(9)sample locations. Low concentrations of DRO were detected in groundwater at eight (8) sample locations (GW-2, GW-4, GW-5, GW-6, GW-7, GW-8, GW-9, and GW-10). The detected concentrations of DRO did not exceed the ESL of 210 mg/L. DRO was not detected above the laboratory reporting limit in groundwater collected from two (2)sample locations(GW 1 and GW-3). EPA Method 6010 -LUFT 5 Metals (Cadmium, Chromium,Nickel, Lead,Zinc) Certain metals were detected in groundwater at four(4) sample locations(GW-4, GW-7,GW-9 and GW-10). Lead was detected in groundwater at three (3) of the 4 sample locations (GW-7, GW-9 and GW-10) and the lead concentrations exceed the ESL of 2.5 gg/L at all 3 locations. Nickel and Zinc were detected at sample location GW-4. The detected concentration of Nickel exceeded the ESL of 8.2 µg/L but the detected concentration of Zinc did not exceed the ESL of 81 gg/L. The