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' 03 January 2002 • AGE-NC Project No 97-0301 ' Page 4of5 changes of recharge/discharge of the local ground water could greatly modify ground water 1 flow direction • The ground water elevation at the site was within the screened intervals of wells MW-1 through MW-4, MW-6 and MW-7, which yield samples fully representative of shallow ' ground water conditions Conversely, the ground water elevation at well MW-5 Is approximately 48 feet above the screen Interval (drowned) and yields a sample more representative of deeper ground water conditions • The core of the dissolvedp etroleum hydrocarbon plume appears to be located In the area wells of MW-1 and MW-7, analysis of ground water samples collected from MW-1 and ' MW-7 suggest the core of the plume Is Impacted by TPH-g, TPH-d, TPH-k, BTEX and 1,2-DCA, very low concentrations of MTBE, EDB and TBA have been detected at MW-1 Indicating that there Is only a minor Impact of these components ' The vertical extent of dissolved petroleum hydrocarbons Is not fully defined at the site, the lateral extent of the dissolved petroleum hydrocarbon plume Is not fully defined toward the ' southeast, east and northeast of the current area bound by wells MW-1 through MW-7 5.0. RECOMMENDATIONS Based upon data collected during September 2001, AGE recommends ' • Continued ground water monitoring utilizing wells MW-1 through MW-7 The next quarterly ground water monitoring event should be performed concurrently with the California Tank- Line Inc site (3105 South El Dorado Street) • Conduct a ground water extraction test to obtain general aquifer characteristics such as hydraulic conductivity, transmisslvrty, storativlty and drawdown at various pumping rates ' Results of the ground water extraction test would be utilized to estimate a radius of influence for the zone of capture of dissolved petroleum hydrocarbons and to Evaluate the feasibility of ground water extraction as a remedial option Cone penetrometer testing (CPT) soil borings were advanced at the site In July 2001, a report of ' findings and recommendations was submitted to the PHS-EHD on 25 October 2001 (Cone Penetrometer Testing Site Investigation - Third Quarter 2001) Based on data collected from the CPT soil borings, AGE recommended Installation of additional deep-screened ground water ' monitoring wells, the screen Intervals for the deep-screened monitoring wells should be placed to define and monitor the extent of the ground water plume In each Informal hydrologic unit identified by the CPT Investigation Advanced GeoEnvironmental,Inc