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• 25 January 2001 AGE-NC Project No 99-0559 Page 3 of 14 southwest of the suspected release MTBE has been detected in samples from well MW-2 at concentrations as high as 310,000 microgram pre liter (µg/1) TPH-g and benzene have been most recently detected in samples from well MW-2 at concentrations of 220,000 µgll and 32,000 µg/l, respectively Samples from each of the four wells currently contain MTBE and benzene above 4,500 µgll and TPH-g at concentrations greater than 26,000 ,ug/l (Table 1) Laboratory analysis of ground water samples collected from two monitoring wells on the northern and eastern property boundaries appear to show that dissolved petroleum hydrocarbons extent off- site The vertical and lateral extent of impacted ground water at the site has not defined, further more increasing concentrations of dissolved hydrocarbons In the ground water monitoring wells Indicate off-site migration of contaminants The mass of dissolved hydrocarbons and MTBE is significant and require off-site assessment and Immediate Interim remediation 3.0. REGULATORY DIRECTIVE AND SCOPE OF WORK Due to the presence of free-product and high concentrations of MTBE beneath the USTs at the site, . the PHS-EHD has directed the assessment of the vertical and lateral extent of the hydrocarbon- and MTBE-impacts to soil and ground water and Initiation of interim ground water remediation The directive requires that a corrective action plan assessing and evaluating the feasibility and implementation of full-scale remediation alternatives be prepared by late June 2001 To achieve the first requirement of the PHS-EHD directive and to assess ground water extraction as a remedial alternative for the site, AGE proposes the following scope of work • Advancement of at least three cone penetrometer testing (CPT) soil borings to develop a geological model of the site and for vertical assessment of hydrocarbons and MTBE, • Installation and monitoring of a minimum of six multi-level' groundwater monitoring wells on and off the site to assess dissolved hydrocarbons and MTBE, and • Installation of an extracted ground water treatment system, and • Initiation of the shallow ground water extraction, treatment and disposal system as an Interim remediation measure to reduce the offsite migration of petroleum hydrocarbons and the fuel additive MTBE • Advanced GeoEnvironmental,Inc