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City of Stockton, Fire Station No. 12 A69105.01 August 7, 1995 Page A-2 laboratory analysis or stored. Soil retained in the two uppermost sleeves is transferred into a plastic bag, agitated to enhance petroleum product volatilization, and field tested for organic vapors with a photoionization detector(PID). (Calibration and operating procedures for the PID are summarized in a following paragraph if applicable to this investigation). Observations of discernable soil discoloration and/or hydrocarbon odors are also be noted. Upon completion of the drilling and soil sampling, each borehole is backfilled with a six- sack sand-cement slurry to site grade. A-2 Decontamination: Decontamination procedures are implemented to reduce the potential for cross-contamination between soil borings. Before, during, and following drilling operations, the augers and associated drilling and sampling equipment are thoroughly cleaned using a high pressure hot water (steam)washer. The hot water washer has a pressure of approximately 1,200 pounds per square inch and a water temperature of approximately 100 degrees Centigrade (°C). The sampler and sleeves are washed in a Alconox® detergent solution, rinsed with clean tap water, and air-dried prior to initial use and between each sampling event. The augers are steam cleaned prior to the drilling of each soil boring. Prior to construction of monitoring wells, all casings are cleaned in the same manner as the drilling equipment. A-3 Sample Handling and Chain-of-Custody: Records are developed for soil and groundwater samples including: sampling date, sample type, location, depth, job number, name of sampling personnel, and method of preservation. Each sample container is labelled immediately following collection in the field. Chain-of-custody protocol,described in United States Environmental Protection Agency (U.S. EPA), 1986, Test Methods for Evaluating Solid Waste, SW-846, 3rd edition, is followed. Samples are placed in an ice chest and maintained at approximately 4°C until they are delivered to the laboratory. The temperature within the ice chest is monitored and recorded during the course of transport and delivery. Samples are accompanied by proper chain-of-custody documentation. Upon `r arrival at the laboratory, the samples are preserved for analysis in accordance with U.S. EPA and state of California requirements. Samples are delivered to Twining's chemistry laboratory in Fresno, California. Analytical methods with corresponding method detection limits and copies of the chain-of-custody records are be provided in the technical report. A-4 Laboratory Quality Assurance/Quality Control (OA/OC): This section describes the laboratory QA/QC procedures which are followed during the analyses of the soil and groundwater samples by Twining's analytical chemistry laboratory. The QA/QC procedures are developed to minimize outside interferences during analyses for each sample. The laboratory manager is in charge of creating and maintaining the ;..+ program. In general, QA/QC proposed for this investigation are summarized as follows: