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N CONSLIUM 2.3 Field Screening The Nova environmental geologist also screened the soil samples collected during the completion of the soil borings for indications of contamination. The soil samples were evaluated for the presence of unusual odors and staining. Additionally, the soil samples were screened for the presence of organic vapors using a ThermoFisher Scientific Model 580B PID. The PID was equipped with a 10.6 eV lamp and was calibrated to an isobutylene standard prior to being used at the Site. A factory-determined response factor was used to correlate the isobutylene response to benzene. The soil samples were screened utilizing the headspace field analysis technique. The headspace technique consists of half-filling a quart sized zip-lock bag with a soil sample and quickly sealing the bag. Headspace development proceeds for at least 10 minutes. The bag is shaken vigorously for 15 seconds,at both the beginning and the end of the headspace development period. After headspace development, the bag is opened slightly and the PID probe is inserted to one-half the headspace depth. The highest reading observed on the PID is then recorded. 2.4 Laboratory Chemical Analyses Soil samples were collected at all of the borings completed at the Site. In the absence of organic vapors and staining, the soil samples were collected from a sampling interval most likely to have been impacted based on the boring rational. Soil sampling information is summarized in Table 2,below. TABLE 2 SOIL SAMPLING LOCATION RATIONALE goring Sampled Number Boring Location Interval Sampling Rationale SB-1 North side of dry cleaner in front of back 2.25'-5' Shallow sample near back door- door. first encountered clay unit. SB-2 West side of building in the assumed 10'-12' Sample above water table. hydraulically downgradient direction. SB-3 and SB-4 Back side of dry cleaner PCE machine. 4'-5' Base of hand auger boring. The soil samples were placed in laboratory-supplied containers, stored in a cooler, and transported to Environmental Science Corporation in Mount Juliet, Tennessee using chain-of-custody procedures. Environmental Science Corporation is certified to analyze environmental samples collected in the State of California. The soil samples were chemically analyzed for the presence and concentration of VOC compounds using Environmental Protection Agency (EPA) method 82608. RALEY'S STOCKTON NOVA PROJECT NO.B13-0472 PAGE 4 APRIL 9,2013