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GEC)-PHASE ENVIRONMENTAL SECOND ADDENDUM to WORK PLAN PRELIMINARY ENDANGERMENT ASSESSMENT Former Haley Flying Service 21,000 Paradise Road, Tracy Envirostor#39070037 February 5, 2007 1.0 INTRODUCTION Reference is made to our original Work Plan dated August 3, 2005, and the subsequent Preliminary Endangerment Assessment (PEA) dated January 18, 2006. Further reference is made to the first addendum to the PEA dated June 23, 2006. The PEA identified the presence of significant pesticide contamination in the shallow soil in an area near the east end of the subject site. Grab groundwater samples collected as a part of the scope of the first addendum from a group of six soil borings identified the presence of low concentrations of organo chlorine pesticides in the groundwater. The soil borings did not, however, produce sufficient information to define the full extent of impacted groundwater. The purpose of this Work Plan is to propose additional tasks intended to more fully define the extent of the groundwater impact, and to obtain additional profiling information on certain characteristics of the soil. Sub-sections 1.1, 1.2, and 1.3 of the original Work Plan provide a site description, the background, and status of the Haley site. Section 5 of the PEA describes the sample results of soil and two groundwater samples collected to date, and the remainder of the groundwater sample results are described in Section 3.4 of the PEA Addendum. 1.1 Scope of Additional Work This Second Addendum to the Work Plan describes a series of additional Geo-Probe soil borings that will be installed along the northern property line of the Haley property and then northerly onto the property adjacent to the site. The purpose is to define the lateral extent of the groundwater contamination in the presumed down-gradient direction. At least two soil samples and a groundwater sample from some or all of these borings will be tested for organo chlorine pesticides. In addition, at least three groundwater monitoring wells will be drilled 2937 Veneman Avenue, Suite B240 Geo-Phase Environmental Inc. Phone: (209)569-0293 Modesto, Ca 95356 Fax: (209)569-0295