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Envlronmental Asseasmant Report 2 <br />0 Chevron U S A Products Company, 103 West 11th Street, Tracy CA A n1 25 1995 <br />23 Soil Borings <br />On March 20, 1995, Groundwater Technology supervised the drilling of sod borings MW4 and MW -5 to <br />a depth of 21 5 feet below ground surface (BGS) utilizing a truck -mounted drill ng equipped with 8 -inch <br />outside -diameter (O D) hollow -stem augers All drilling equipment was steam -cleaned prior to drilling, <br />and sampling equipment was washed in an Alconox (detergent) solution and rinsed with water between <br />sampling intervals All soil generated from the bonngs was placed in U S Department of <br />Transportation (DOT) -approved 55 -gallon drums Drums were appropriately labeled, sealed and <br />stored on site, pending removal and disposal by Integrated Wastestream Management, Inc , of <br />Milpitas, CA <br />24 Soil Sampling <br />Soil samples were collected from boreholes MW -4 and MW -5 at 5 -foot intervals during drilling, <br />beginning at approximately 5 feet BGS Samples were collected using a 2 5 -inch O D split -spoon <br />sampler, lined with three 2 -inch -diameter by 6 -inch -long brass sample tubes The sampler was driven <br />18 inches ahead of the augers at each sample point Sod samples were field screened for <br />hydrocarbon vapors using a photo -ionization detector Soil encountered was logged using the Unified <br />Sod Classification System by a Groundwater Technology field geologist working under the supervision <br />of a California registered geologist (Appendix B) One sample tube from each 5 -foot interval was <br />sealed, labeled and placed on ice in an insulated container for transport under chain -of -custody <br />manifest to GTEL Environmental Laboratories, Inc (GTEL), a California state -certified analytical <br />laboratory in Concord <br />Sod samples collected from the 6-, 11- and 16 -foot depths from borings MW -4 and MW -5 were <br />submitted for laboratory analysis, as well as the soil sample collected from the 21 -foot depth from <br />bonng MW -4 Poor recovery of water -saturated sod prevented sample collection from the 21 -foot <br />depth of boring MW -5 Samples were analyzed for benzene, toluene, ethylbenzene and total xylenes <br />(BTEX), and total petroleum hydrocarbons -as -gasoline (TPH-G), using U S Environmental Protection <br />Agency (EPA) methods 5030/8020/modified 8015 <br />2.5 Groundwater Monitoring Well Installation and Development <br />A groundwater monitoring well was installed in each of bonngs MW -4 and MW -5 on March 20, 1995 <br />The monitoring wells were constructed of 2 -inch -diameter schedule 40 PVC blank casing and <br />0 020 -inch slot well screen with flush threads Well screen was installed at a depth of 5 to 20 feet BGS <br />in each well A #3 -sand filter pack was installed in the annulus from the bottom of each borehole to 2 <br />feet above the top of the well screen, followed by a well seal consisting of a 2 -foot thick bentonite layer <br />overlain by neat cement (grout) to ground surface Each well was secured by a locking expandable <br />well cap and fitted with a traffic -rated well box set in concrete Details of well construction are <br />• 0055EAR RPTIChv471 <br />❑� GROUNDWATM <br />❑ ❑ TECH NOL OGY <br />