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: 1 1 29 March 2004 . AGE-NC Project No. 97-0327 Page 7of12 concentration at 480 mg/kg, BTEX compounds at concentrations as high as 1.8 mg/kg and MTBE concentration at 0.89 mg/kg. Low concentrations of TPH-d (7.7 mg/kg)Vand ethylbenzene (0.053 mg/kg)were detected at 45 feet bsg from P-12. TAtI y 9 1 4.3. SATURATED ZONE PETROLEUM-IMPACT Soil samples collected below a depth of 60 feet bsg are representative of the saturated zone. Petroleum hydrocarbon-impacted saturated-zone soil was not encountered in any soil samples ' collected from the saturated zone. ' 4.4. VOLUMETRIC CALCULATIONS Based on Figures 5 through 10, wells MW-2 and MW-3 and soil borings P-1, P-2, P-3, P-5, P-8, ' P-10 and P-11 are all located within the modeled adsorbed petroleum hydrocarbon-impacted soil plume. The equations for an elliptical cone, a cylindrical ellipse and Autocad (drawing program)- determined area multiplied by thickness were utilized to estimate the mass and volume for gasoline- and diesel-impacted soil. When the data collected at the site is plotted in both plan view and cross sectional views,-the apparent total volume of gasoline-impacted soil totaled approximately 1,609 cubic yards,which yields approximately 161 gallons of gasoline,or an estimated 1,007 pounds . of gasoline remaining in soil. The apparent total volume 'of diesel-impacted soil encompassed approximately 2,003 cubic yards,which yields approximately 1,116 gallons of diesel,or an estimated 6,974 pounds of d+1 remaining in soil. Mass/volume calculations are included in Appendix D. 1 � 5.0. GROUND WATER MONITORING PROGRAM Between February 2000 and September 2003, twelve ground water monitoring events were ' performed at the site to characterize ground water flow direction and gradient,and monitor dissolved petroleum hydrocarbon concentrations in ground water. Additionally, in accordance with a verbal directive from the SJCEHD, AGE collected water samples from domestic water wells located at ' 451 and 452 North Lillian Avenue in January 2004 for laboratory analysis; a third domestic well located at 503 North Oro Avenue was reported removed by the property owner. Since initiation -of ground water monitoring, ground nwater elevations have ranged from .- _. _. _ approximately 19.31 to 34.74 feet below mean sea level, and the dominant ground water flow direction has been between south-southwest and south-southeast. Representative maps of ground ' water elevations from the years 2000 through 2003 are presented as Appendix A. 1