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First Quarter 1993 Monitoring Report Coca-Cola Enterpnses- West Project No 54006 02 Page 2 1990, an additional subsurface investigation in October and November 1990; and quarterly groundwater monitoring The results of these investigations are presented in the reports listed at the end of this report A soil vapor extraction test was conducted at the site by RESNA in ' November 1992 (RESNA, January 1993) Investigations have shown that the majority of petroleum hydrocarbons in the soil were present from 0 to approximately 25 feet below grade and within a radius of about 20 feet of the former 1,000 gallon gasoline UST tank pit. Quarterly ' groundwater monitoring results have shown detectable levels of petroleum hydrocarbons in the monitoring wells (Table 1). GROUNDWATER SAMPLING AND GRADIENT EVALUATION ' RESNA personnel performed the latest quarterly groundwater monitoring of monitoring wells on March 11, 1993 Mr Michael Collins of SJCPHS was present on-site to observe RESNA ' sampling techniques Field work consisted of measuring depth-to-water (DTV) levels in wells MW-1 through MW-6, collecting groundwater samples from wells MW-1, MW-2, and MW-6, and submitting groundwater samples for laboratory analysis Water level measurements were collected from wells MW-1 through MW-6 The depth to water ranged from 71.13 to 71.76 below top of well casing elevation. In general, groundwater ' elevations have increased an average of 2.78 feet since December 17, 1992. The water level data were used to develop the groundwater elevation contour map (Plate 3) Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site ' flowed in an easterly direction The hydraulic gradient on March 11, 1993 was calculated to be 0.001 ft/ft or about 7 feet/mile These data indicate a slight seasonal change when compared with previous results for gradient and flow direction A summary of groundwater monitoring ' data is presented in Table 2. Groundwater elevations are referenced to feet mean sea level. Groundwater samples were collected from three shallow groundwater monitoring wells, MW-1, ' MW-2, and MW-6 Prior to collection of groundwater samples a minimum of three well volumes (casing and sandpack)was purged The depth-to-water,pH, electrical conductivity, and temperature were measured and allowed to stabilize before groundwater samples were collected tNo evidence of measurable floating product or hydrocarbon vapor was noted in the water samples Samples were then collected from each well using disposable bailers. Purge water was contained in 55 gallon DOT approved drums and stored on-site ' Theroundwater samples collected from g p each well were submitted with Chain of Custody Record to RESNA Analytical Laboratories of Fremont, California, a State Certified laboratory (State Hazardous Waste Testing Laboratory Certification No 1211). Samples were analyzed for total petroleum hydrocarbons as gasoline (TPHG), total petroleum hydrocarbons as diesel ' 1QMRt993 FNi. 1