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RECEIVED JIN09020116 Appendix A - Site Background Information ENVIRONMENTAL Page 3 of 5 HEALTH DEPARTMENT potential vertical conduits within a 2,000 foot radius of the site. The results of the sensitive receptor survey located a municipal water well (City of Manteca Well No. 4) located approximately 1,900 feet northwest of the site near and a second municipal water well (City of Manteca Well No. 5) located approximately 1,500 feet south of the site. Results of the investigation were reported in Sensitive Receptor Survey, dated 08 September 2000 prepared by AGE • December2000-Four additional soil borings(P-7 through P-10)were advanced on- and off-site utilizing cone penetrometer testing(CPT)technology to characterize the geological and hydro-geological framework and to assess preferential migration pathways. Based on the CPT soil characteristics data, AGE identified four potential hydrogeologic units informally identified as "First Water Zone" (located 15 to 47 feet bsg), "Second Water Zone"(located 58 to 92 feet bsg), "Third Water Zone" (located 102 to 115 feet bsg) and "Primary Aquifer Zone" (located 128 to 150 feet bsg). Significant fuel component and chlorinated solvent-impact to groundwater was reported from the First Water Zone; low to moderate fuel component and chlorinated solvent-impact was reported from Second Water Zone, Third Water Zone and Primary Aquifer Zone from P-7, P-8, P-9 and P-10. Results of the December 2000 CPT investigation were reported in Cone Penetrometer Testing Site Investigation - Fourth Quarter 2000, dated 07 February 2001, prepared by AGE. • March 2001 -Groundwater extraction well EW-1 and ground water observation well MW-6 were installed on-site for performance of a groundwater pumping test. Soil borings EW-1 and MW-6 were advanced to depths of 45 feet bsg. Boring EW-1 was single-completed as a 6-inch diameter groundwater extraction well and MW-6 single-completed as a 2-inch diameter groundwater observation well with screen intervals between 20 and 45 feet bsg. Soil and groundwater samples were not collected during this investigation. Results of the March 2001 investigation were reported in Groundwater Aquifer Pumping Test Report - Second Quarter 2001, dated 15 May 2001, prepared by AGE. • April 2001 - A groundwater aquifer pumping testing was performed at the site to assess the general aquifer characteristics and to assess aquifer response to groundwater extraction utilizing wells EW-1, MW-1, MW-2, MW-3 and MW-6 at a constant pumping rate of 6 gallons per minute. From the pump test, a transmissivity value was calculated at 955 W/day, a storativity value calculated at 0.032, a hydraulic conductivity value of 0.013 cm/s and a groundwater radius of influence projected at 140 feet utilizing a semi-logarithmic plot of draw-down versus distance. Results of the March 2001 investigation were reported in Groundwater Aquifer Pumping Test Report - Second Quarter 2001, dated 15 May 2001, prepared by AGE. • January 2002-Interim groundwater pump-and-treat(P&T)remediation was initiated Advanced GeoEnvironmental,Inc.