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Phase iI Environmental Site Assessment Multi-Modal Station Stockton,San Joaquin County,Califomta Page 10 • 5.2.5 Block 4 Between September 9 and September 16, 2002, ten Geoprobe borings, 16 detection borings, and four hydropunch bonngs were Installed on three parcels of Block 4 Geoprobe, detection, and hydropunch boring locations for Block 4 are shown in Figure 9,Appendix A Four Geoprobe borings (GBK4-7301 through GBK4-730-4), 14 detection borings (DBK4-730-1 through DBK4-730-14), and three hydropunch bonngs (14BK4-730-1 through HBK4-730-3) were installed at 730 E Channel Street,a former bus depot ■ Geoprobe boring GBK4-730-1, detection borings DBK4-730-1 through DBK4-730-10, and hydropunch boring HBK4-730-1 were installed in a paved parking area in the northwest corner of the property ■ Detection borings DBK4-730-11 through DBK4-730-13 were Installed inside the former maintenance building ■ Geoprobe borings GBK4-730-2 through GBK4-730-4, detection boring DBK4-730-14, and hydropunch borings HBK4-730-2 and HBK4-730-3 were installed in the property's southern paved parking area ➢ Four Geoprobe borings (GBK4-701-1 through GBK4-701-4), two detection borings (DBK4-701- 1 and DBK4-701-2), and one hydropunch boring (HBK4-701-1) were installed in the paved parking area at 701 E Weber Avenue ➢ Two Geoprobe borings (GBK4-729-1 and GBK4-729-2) were installed in the paved parking area at 729 E Weber Avenue, a retail tire business Field observations and PID measurements indicated that soil cores from several of the borings installed at 730 E Channel Street were impacted by contaminants ➢ Hydropunch boring HBK4-730-1 - Advanced to a total depth of 110 feet bgs to allow for sampling of deeper groundwater at this location in order to investigate the vertical extent of hydrocarbon contamination This hydropunch boring was coupled with detection boring DBK4- 730-9 ➢ Detection boring DBK4-730-14 -A slight petroleum hydrocarbon odor was noted an approximate depth of 15 feet bgs The corresponding PID measurement was 134 parts per million(ppm) ➢ Detection boring DBK4-730-4 - Slight to moderate petroleum hydrocarbon odors and moderate PID readings up to 54 8 ppm were noted in the soil samples ➢ Detection boring DBK4-730-5 - A moderate petroleum hydrocarbon odor was noted in soil samples collected from between 15 feet and 45 feet bgs and corresponding PID readings ranged from 61 0 ppm to 591 ppm During subsequent groundwater elevation measuring activities, a petroleum odor was noted on the depth-to-water probe ■ Detection boring DBK4-730-10 - Advanced to a total depth of 55 feet bgs, 10 feet below the deepest impacted soil Indications of contamination were noted in soil samples collected from between five and 15 feet bgs, consequently, continuous soil cores were collected between 15 feet and 35 feet bgs A strong petroleum hydrocarbon odor was noted in soil samples from approximately five feet bgs to 45 feet bgs Corresponding PID readings ranged from 610 to 3,800 ppm The boring log for DBK4-730-10 is included in Appendix D ■ The organic vapor concentrations measured for all screened soil samples collected between 14 5 feet and 34 5 feet bgs ranged between 3,200 ppm and 3,800 ppm These recorded measurements were displayed briefly by the PID before the instrument measuring capabilities were exceeded �t� CONDOR