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ERI 205503 Rol Unocal Service Station 5886 Stockton California lune 3 1997 FIELD PROTOCOL Site Safety_ Plan Field work is performed by ERI personnel in accordance with a site safety plan developed for the site This plan describes the basic safety requirements for the subsurface investigation and the drilling of soil borings at the work site The site safety plan is applicable to personnel and subcontractors of ERI Personnel at the site are informed of the contents of the site safety plan before work begins A copy of the site safety plan is kept at the work site and is available for reference by appropriate parties during the work The ERI geologist acts as the Site Safety Officer Soil Borings and Sampling Prior to drilling of borings and construction of wells, ERI acquires necessary permits from the appropriate agency(ies) ERI also contacts Underground Service Alert (USA) before drilling to help locate public utility lines at the site ERI hand-probes and hand-augers boring locations to a depth of approximately 5 feet bgs and a diameter greater than the soil boring diameter before drilling to reduce the risk of damaging underground structures Soil borings are drilled with a CME-55 (or similar) drill rig equipped with 10-inch diameter, hollow- stem augers Auger flights and sampling equipment are steam-cleaned before use to minimize the possibility of crosshole contamination The rinseate is containerized and stored on site ERI will coordinate with Tosca for appropriate disposal of the rinseate . Drilling is performed under the observation of a field geologist, and the earth materials in the borings are identified using visual and manual methods, and classified as drilling progresses using the Unified Soil Classification System Soil borings are drilled to approximately 10 feet below the uppermost zone of saturation or 5 feet into any competent clay layer (aquitard) encountered beneath the water- bearing zone If an aquitard is encountered, the boring is terminated and backfilled with bentonite before installing a groundwater monitoring well During drilling, soil samples are collected at 5-foot intervals, obvious changes in lithology, and dust above the groundwater surface Samples are collected with a California-modified, split-spoon sampler equipped with laboratory-cleaned brass sleeves Samples are collected by advancing the auger to a point,lust above the sampling depth and driving the sampler into the soil The sampler is driven 18 inches with a standard 140-pound hammer repeatedly dropped 30 inches The number of blows required to drive the sampler each successive 6-inch interval is counted and recorded to give an indication of soil consistency Soil samples are monitored with a photoionization detector (PID), which measures hydrocarbon concentrations in the ambient air or headspace above the soil sample Field instruments such as the PID are useful for indicating relative levels of hydrocarbon vapors, but do not detect concentrations of hydrocarbons with the same precision as laboratory analyses Soil samples selected for possible chemical analysis are sealed promptly with TeflonB tape and plastic caps The samples are labeled and placed in iced storage for transport to the laboratory Cham of Custody Records are initiated by the geologist in the field, updated throughout handling of the samples, and sent with the samples to the laboratory Copies of these records are in our report Cuttings generated during drilling are placed on plastic sheeting and covered and left at the site ERI coordinates with Tosco for the soil to