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�1 URS lie, Ms Margaret Lagorio, Supervising REHS Page 3 of 7 San Joaquin County Environmental Health Department February 16, 2005 liners,capped with Teflon°tape and plastic end caps, labeled, sealed in clean resealable bags, and placed in a cooler on ice for delivery to Sequoia Analytical Laboratories (Sequoia) in Morgan Hill, California, under chain of custody No hydrocarbon odor or staining was observed in any of the soil samples, and a PID indicated readings of 0 parts per million (ppm)for volatile organic compounds (VOCs)for all depth intervals sampled during drilling The samples collected from the capillary fringe at approximately 60 feet bgs in borings B-28 and MW-4 and samples collected from 50, 60, 100, and 105 feet bgs in boring MW-5 were selected for laboratory analysis ' Grab Groundwater Sampling Grab groundwater samples were collected from first encountered groundwater in boring B-28 through the HSAs Prior to collecting grab groundwater samples, the augers were connected to the cable winch and withdrawn 3 feet above the top of the aquifer This was conducted to minimize contact with potentially impacted shallow soils that may have been drawn down with the augers The groundwater samples were collected using a new disposable bailer All samples retained for analysis were collected in glass volatile organic analyte (VOA)containers with self-sealing screw-on caps, labeled, and placed in a cooler on ice for delivery to Sequoia in Morgan Hill, California, under chain of custody Laboratory Analytical Methods All soil and groundwater samples selected for laboratory analysis were analyzed for gasoline range organics (GRO)by United States Environmental Protection Agency (EPA) Method 8015B/8021B (preparation EPA Method 5030 for soil), benzene, ethylbenzene, toluene, xylene, (BTEX), methyl tert- butyl ether(MtBE), tert-butyl alcohol (TBA), di-isopropyl ether (DIPE), ethyl tert-butyl ether(ETBE), tert-amyl methyl ether (TAME), 1,2-DCA, ethylene dibromide (EDB), and ethanol by EPA Method 8260B (preparation EPA Method 5030 for soil) Shallow and Deep Monitoring Well Installation Monitoring wells MW-4, and MW-5 were constructed using 2-mch diameter, schedule 40, flush- threaded polyvinyl chloride (PVC) well casing Total depths of wells MW-4 and MW-5 are 70 feet, and 104 feet, respectively Fifteen feet of 0 020-inch, machine-slotted well screen was set between 55 feet and 70 feet bgs for MW4, and 5 feet of screen was set between 99 feet and 104 feet bgs for MW-5 A Monterey No 3 silica sand filter pack was installed from the bottom of each boring to 2 feet above the top of each well screen A 3-foot bentonite seal was placed above each sand pack, and neat cement was used to fill the annular space to within I foot of the surface Each well was completed with a traffic- rated, flush-mounted well box and a locking well cap was placed on the top of the casing Well construction details for these wells are presented in Attachment B Groundwater Monitoring Well Development, Sampling, and Surveying On December 9, 2004, Blaine Tech Services, Inc (Blaine Tech) developed groundwater monitoring wells MW-4 and MW-5 by rigorously surging over the length of the screened intervals and by pumping approximately 10 gallons of water from MW-4 and 60 gallons of water from MW-5 The turbidity and K lwproces5li5 BP ARCO\0076012004 Assessment1760 additional assessment report 04 doc