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1 I Ir i I I Is I I A p I , , F i r , ✓1 SIM I Lf 18 April 2003 I � AGE-NC Project No 97-0333 f I Page 9 of 11 4.0. SUMMARY'AND CONCLUSIONS Pfevlous soil characteristics data obtained by a CPT investigation enabled AGE to define four -informal hydrologic units(CPT Sate Investagataon -Fourth Quarter 2000,dated 07 February2001) ,I The informal hydrogeologic units were defined First Zone(15-47 feet bsg),,Second Zone (58-92 , feet bsg, Third Zone (102-120 feet bsg) and Primary Aquifer Zone (128-150 feet bsg) ` 'I The results of pump and treat ground water remediation between 26 September and 12 December I I „ 1 -'2002 are as follows „ 'I eI t € Approximately 27 8,64 0 gallons of hydrocarbon-imp acted ground water were extracted from well EW-1,which was completed in the-First Zone aquifer A total volume of approximately k 934,104 gallons of hydrocarbon-impacted ground water has been treated at the site since the ' ' start-up period in January 2002 (Table 5) • Dissolved MTBE was detected from grab' samples collected at the influent-end'of the ' ' treatment system at concentrations between 5,400 µg11 and 13,000 µg/l, laboratory analysis of grab water samples collected at the effluent-end of the pump and treat system detected MTBE on one occasion (12 December); however, the effluent-end was!re-sampled on 02, 10 January 2003 and the laboratory reported MTBE was non-detect at less than 0 5 µg/l No other constituents of concern were detected(Table 1) i ' Between 26 September and 12 December 2002, an estimated 22 94 pounds of MTBE was extracted from'ground water(Table 5,Appendix B), a total mass of 189 31 pounds of MTBE I I ' has been removed since initiation of the pump and treat system on 21 January 2002 'A plot I of cumulative ground water pump and treat mass removal versus time and a plot of influent 1 I ground' water MTBE concentrations,versus time are included in'Appendix C, although I !moderate increases was reported in November and December 2002,the overall general trend ' of decreasing MTBE concentrations is evident ' The results from the ground water monitoring and sampling events performed in Novemberr2002 are as follows ! ' 'Generally,depth to ground,water at the site varied between 20 and 22 feet bsg,ground water H I N ;I „ rllk � I a ,i ryll elevations range betweenI?11 OS feet(MW-1'1D) and 11,64 feet(MW-10B)below mean sea level 'The ground water elevation,increased approximately 0 37 feet between August and{ ' NoveImber 2002,'the average Increase in may be due to seasonal fluctuation First Zone ground water flow was inferred to be towards a,ground water depression In the area of wells MW-2, MW-6, MW-7 and EW-1 at an approximate gradient of 0 004 ft1fl or less, off-site in the area of wells MW-1'1,MW-12 and MW-13,ground water appeared to be I' onented towards the a'north-northwest (Figure 4) r ;_ "� I II I, ti fr IV i 1 + I1 I I I I Advanced GeoEnvironmental,Inc I �i I I I III If 4 I I t I Id IF k I I I!I Illlll E! I II!I l r E I I ul� I aI I I,