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ro <br /> Working To Restore Nature <br /> December 8, 1992 <br /> Fire Engine Company No 2, Stockton, California <br /> WELL INSTALLATIONS <br /> Between August 28 and September 2, 1992, a geologist from RESNA observed Wayne <br /> Drilling of Lincoln, California, drill five soil borings (B-9 through B-13) at the site Soil <br /> samples were collected at approximately 5-foot intervals during drilling, identified using <br /> visual and manual methods, and classified according to the Unified Soil Classification <br /> System (Plate 3) The subsurface materials encountered in the borings consisted of <br /> interbedded clayey silt, silt, sand, and gravel Descriptions of the materials logged are <br /> presented in the Logs of Borings (Plate 4 through 15) Ground water was encountered at <br /> approximately 48-1/2 feet below grade <br /> Wayne Drilling installed vapor-extraction wells VW-1, VW-2, and VW-3 in borings B-9, B- <br /> 10, and B-11, respectively, a piezometer (PZ-1) in boring B-12, and recovery well RW-1 in <br /> boring B-13 Well construction details are illustrated on the Logs of Borings A technician <br /> from RESNA developed well RW-1 on September 10, 1992, field procedures for well <br /> development are attached <br /> On September 9, 1992, Tom Morrow, Inc of West Sacramento, a licensed land surveyor, <br /> surveyed the locations and elevations of the piezometer, ground-water monitoring, ground- <br /> water recovery, and vapor-extraction wells Elevations were surveyed to mean sea level <br /> Four soil samples were collected from the drill cuttings and composited into one sample in <br /> the laboratory for laboratory analyses The City of Stockton is responsible for the disposal <br /> of the drill cuttings <br /> Analytical_Results of Soil Samples <br /> Soil samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg) using <br /> modified Environmental Protection Agency (EPA) Method 8015 and benzene, toluene, <br /> ethylbenzene, and total xylene isomers (BTEX) using EPA Method 8020 Laboratory <br /> analyses were performed at RESNA Environmental Laboratories in Fremont, California <br /> (Hazardous Waste Testing Laboratory No 1211) Copies of the Chain of Custody Records <br /> and laboratory reports are attached The results of analyses are summarized in Table 1 <br /> Results indicated residual gasoline hydrocarbons were not detected in soil samples collected <br /> from boring B-11 Concentrations of TPHg in samples from borings B-9, B-10, and B-13 <br /> ranged from less than the detection limit (10) to 7,000 parts per million <br /> ii0 <br /> � 38Q009-49-4 <br /> 2 <br />