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f <br /> 25 September 1995 <br /> AGE-NC Project No 95-0137 <br /> ' Page 2 of 6 <br /> ' EHD)dated 7 March 1994 indicated that closure of the former underground storage tanks could not <br /> be granted until further soil and ground water assessment had been completed Geological Audit <br /> Services, Inc (GeoAudit)was retained to assess the soil and ground water contamination at the site <br /> 23 INITIAL INVESTIGATION <br /> t <br /> ' On April 27 and 28, 1994, eight sod borings were dulled at the site Three of the bonngs were <br /> completed as 2-inch groundwater monitoring wells Soil samples were collected at five-foot intervals <br /> during drilling A total of fourteen soil samples were submitted to a state-certified laboratory for <br /> analysis Total petroleum hydrocarbons quantified as gasoline(TPH-g) was detected in ten samples <br /> at concentrations up to 3,800 ppm(134-20) Total petroleum hydrocarbon quantified as diesel (TPH- <br /> ' d) was detected in twelve samples at concentrations up to 9,000 ppm (118-20) During dnllmg, <br /> groundwater was encountered at a depth of approximately 20 feet <br /> ' After installation,the depth to groundwater was measured in and samples were collected from each <br /> well The hydraulic gradient was calculated to be 0 0006 fl/ft, directed S 40° W TPH-g was detected <br /> in MW-1, MW-2 and MW-3 at concentrations of 1,700 pg/1 (ppb), 14,000 ppb and 2,600 ppb, <br /> respectively TPH d was detected m MW-1,MW-2 and MW-3 at concentrations of 2,400 ppb, 9,200 <br /> ppb and 6,900 ppb, respectively <br /> 3.0. PROCEDURES <br /> 3 1 MONITORING WELL PURGE PROCEDURES <br /> ' On 24 May 1995, a Sohnst water level meter was used to measure the depth to ground water in wells <br /> MW-1, MW-2 and MW-3 The relative piezometnc level in each well and hydraulic gradient were <br /> calculated from these data(Table 1) Each momtonng well was purged of approximately 7 gallons <br /> 1 of water (a minimum of three well volumes) using a clean two-stage submersible pump <br /> Temperature, pH, and conductivity were measured at approximately one-gallon intervals using an <br /> ICM Water Analyzer Model #52200 Monitoring well stabihzation data and field data sheets are <br /> ' included in Appendix A Purged water was stored on-site in 55-gallon drums <br /> ' 3 2 GROUND WATER SAMPLE COLLECTION <br /> On 25 May 1995, water samples were collected from each purged well using a new, clean, disposable <br /> Teflon bailer The samples were transferred into 40-m1 EPA vials, preserved with hydrochloric acid, <br /> and 1-liter amber bottles Samples were transported in a chilled container, under chain-of-custody to <br /> Pan Ag Laboratory, in Madera, California The samples were analyzed for TPH-g, TPH-d and <br /> 1 <br />