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Phase li Environmental Site Assessment Mulu-Modal Station Stockton,San Joaquin County,California Page 6 • 4.2.4 2 Soil Sampling Procedures and Laboratory Analyses Continuous core soil samples were collected from 5 to 15 feet bgs for laboratory analyses from the Geoprobe and detection bonngs The soil samples were collected in clean acetate sleeves installed in five- foot long macro core samplers Three soil samples, each approximately four inches long, were cut from the acetate liners at depths of approximately 5, 10, and 15 feet bgs The ends of the acetate liners were covered with Teflon® sheeting and capped with plastic end caps The samples were labeled for identification and placed in a cooler chilled with ice The remainder of the acetate liner was opened for lithologic logging and other observations A grab sample of soil from each recovered acetate liner was placed in a re-sealable plastic bag for headspace screening of volatile organic vapors with a PID If soil contamination was observed in field samples below 15 feet bgs, additional soil samples were collected at approximately five-foot intervals through the apparent extent of impacted soil and retained for analyses The soil sampling equipment was cleaned prior to collecting each sample by washing in a solution of laboratory-grade, non-phosphate detergent and deionized water, and double-rinsing with deionized water Upon completion of the daily fieldwork, the soil samples were delivered by courier, under chain-of- custody procedures, to Excelchem Environmental Labs, Inc , in Roseville, California The three soil samples collected from each boring at 5, 10, and 15 feet bgs were typically composited in a three-to-one ratio by the laboratory and analyzed for volatile organic compounds (VOCs) by Environmental Protection Agency(EPA) Method 8260B If soil contamination was identified by field observation or PID screening, the three soil samples collected between five and 15 feet bgs, as well as any additional soil samples collected from depths greater than 15 feet bgs, were analyzed discretely for VOCs by EPA Method 8260B Analyses including those for semi-volatile organic compounds (SVOCs) by EPA Method 8270C, • petroleum hydrocarbon constituents by EPA Method 8015m, and the 17 California Administrative Manual (CAM) metals by EPA Methods 6010B and 7471A were held pending the results of the VOC analysis 4.2.4.3 Groundwater Sampling Procedures and Laboratory Analyses Groundwater samples were collected from the detection and hydropunch borings In an attempt to obtain representative depth to water data, and minimize sample turbidity, a temporary well screen was installed in the detection borings, and these borings were allowed to stand open until the end of the day in which they were installed The depth to water measurements and groundwater samples were collected from the borings in the same order that they were installed Prior to sample collection, the water level in each detection boring was measured to the nearest 0 01 foot with a battery-operated water-level meter The depth to water was referenced to the ground surface adjacent to the boring The water-level meter was cleaned prior to measuring the depth to water in each boring by washing it in a solution of laboratory- grade,non-phosphate detergent and deionized water, and double-nnsing with deionized water The detection and hydropunch borings were sampled using polyethylene tubing fitted with a stainless steel check valve The sample containers were slowly filled directly from the sample tubing in order to minimize sample agitation Each water sample was collected in a minimum of three 40-milliliter (mL) volatile organic analysis (VOA) vials, two one-liter amber glass containers, and one 250-mL plastic container Each sample container was labeled for sample identification and placed in a cooler chilled with ice Following the collection of the groundwater samples, the detection and hydropunch borings were backfilled with neat cement grout at the end of each day . Upon completion of the daily fieldwork, the groundwater samples were delivered by courser, under chain- of-custody procedures, to Excelchem Environmental Labs,Inc , in Roseville, California The groundwater 1 1 4 �t� CONDOR