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15 July 2002 AGE -NC Project No 96-0232 Page 18 of 21 which then migrated through the First Zone and upper Second Zone to the former Rocky's Restaurant domestic well, at which point it apparently migrated vertically to the Rocky's Upper, Secondary Aquifer and Primary Aquifer Zones Between December 2001 and June 2002, significant concentrations of dissolved MTBE were detected from Second Zone well MW -8A (screened 40 to 50 feet bsg) However, intermediate well MW -4, located between MW -8 and the UST area, continued to have no detection of MTBE, albeit screened in the Fust Zone Since initiation of ground water extraction activities at the site, ground water flow direction in the First Zone in the area of MW -8 has generally been inferred to be towards the south-southwest, ground water flow direction in the Second Zone in the area of MW -8 has been inferred towards a slight depression in the water table located between wells MW -6B and MW -9A, it is not clear at this time why substantial MTBE is present in MW -8A after nine consecutive quarters of being non -detect Between March 2002 and June 2002, moderate to substantial MTBE decreases were reported from wells MW -8A, MW -11A, MW -11B, EW -4 and EW -5, subtle MTBE decreases were reported in extraction wells EW -6, EW -8 and EW -10 and monitoring wells MW -11D and MW -12A Conversely, subtle MTBE increases were reported from monitoring wells MW -7, MW -13A and Three B's Truck Plaza well MW -4 The data implies that the decreases may be due to the overall MTBE mass reduction in First Zone water and possibly Second Zone (MW -11 A) and Upper Rocky's Zone water (MW -11B), the subtle increases at MW -7 and Three B's Truck Plaza well MW -4 may be due to the well abandonment of RDW -1, which may have caused a rebound effect due to discontinued pumping activity at RDW -1 AGE estimates the arithmetic average concentration of MTBE in ground water extracted between 27 March and 13 June 2002 was 27 4g11 During this time, the volume of water processed through the ground water pump and treat system was recorded at 1,075,700 gallons (equivalent to 8,968,111 pounds) of water extracted yields 0 22 pounds of MTBE (equivalent to 100 grams) removed from the plume of impacted ground water (Appendix D), or approximately 1 5 grams per day Analytical results from the June 2002 quarterly monitoring event indicates the most intense on-site MTBE impact is in the First Zone near EW -4 (29 ,ug/1) and in the Second Zone near MW -8A (250 µg/1), the most intense off site MTBE impact is in the First Zone near MW -7 and Three B's Truck Plaza well MW -4 (49 1.ig/1 and 90 µg11, respectively), and in the Rocky's Upper Zone well MW -11B (120 4g/1) It is not clear at this time why the Three B's Truck Plaza well MW -4 has consistently had greater MTBE -impact than that of intermediate well MW -7 Significant concentrations of TPH-mo and TPH-d were quantified west of the site in the area of . MW -12A and MW -13A, which suggest the possibility of separate releases Advanced GeoEnviranmentai, Ine-