ARCHIVED REPORTS XR0001898 - Laserfiche WebLink

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HEALTH AND SAFETY PLAN TPH as diesel was also detected in soil samples collected from boring B-2 (38 mg/kg at 12 feet bsg), boring B-4(27 mg/kg at 10 feet bsg) and boring B-5 (19 mg/kg at 10 feet bsg, 1 1 mg/kg at 20 feet bsg, ' 1,800 mg/kg at 25 feet bsg and 3,200 bsg at 31 feet bsg) Based on the information provided to us, HETI proposes to conduct a Phase II ESA investigation to determine the lateral and vertical extent of the petroleum contamination as required by the PHS/EHD To ' accomplish this, HETI will conduct the following tasks Task 1. Subsurface Soil and Ground Water Investigation ' HETI personnel will conduct an initial on site subsurface soil and ground water exploration near previous known contaminant hot spots as determined from the initial URSGWC investigation Prior to any ' subsurface investigations,HETI will obtain the required PHD/EHD permits Soil boring locations will be marked prior to drilling ' Soil samples will be obtained from at least six direct push(DP)borings using a Stratprobe DP drilling ng Soil samples will be collected at 5 0-foot intervals beginning at 10 feet bsg(the approximate bottom of the UST excavation) to 50 feet bsg(assuming that the shallow ground water table is approximately 40 ' feet bsg) Samples will be submitted using the appropriate chain of custody At least three ground water monitoring wells will be installed, using hollow stem auger, in the shallow unconfined saturated zone using 2 0-inch PVC Monitoring wells will be screened from approximately 5 0 feet above the ground water table to 15 feet below the ground water table However, based on the URSGWC report, the silt and clayey silt soil layer at approximately 44 feet bsg to 53 feet bsg may represent an aquitard Therefore,monitoring wells may not be screened to depths deeper than 45 feet bsg ' One monitoring well will be installed up gradient from the contaminant plume,two monitoring wells will be installed down gradient Ground water monitoring wells will be installed after completion of the initial soil boring investigation Completed monitoring wells will be purged,sampled and surveyed by a ' California licensed surveyor Soil cuttings and rtnsate water will be drummed in 55-gallon UN rated steel drums that will be sampled ' and managed according to sample analyses Task 2• Sample Analysts ' Soil and ground water samples will be analyzed for TPH as diesel, TPH as gasoline,benzene, toluene, ethylbenzene,and total xylenes(BTEX)with methyl-tertiary butyl ether(MTBE)using USEPA Methods Collected samples will be submitted to a California accredited laboratory for analysis ' Task 3 Report ' HETI will prepare a written report of the findings Page 2 of 27 t