ARCHIVED REPORTS_MONITORING WELL M-10 INVESTIGATION REPORT 2010

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M-10A Investigation Report November 30, 2010 Nestle USA, Inc., Ripon, California The field investigation was conducted in phases. The objective of the first phase was to define the depth resolution and distribution of COC-affected groundwater near M-10A. This phase included CPT locations in an east-west oriented transect aligned with the M- 10 well cluster. Initially, two boring locations (CPT-199 and CPT-20) adjacent to the M- 10 well cluster were drilled to the base of the A zone to identify the major coarse-grained units within the A zone. The second phase of the investigation involved drilling and sampling in the target zones at the north transect area oriented northwest-southeast along Stockton Avenue and at the south transect area, oriented east-west south of Main Street. The CPT locations were sited in these areas based on the extent of CDCs identified along the initial transect and the northwest groundwater flow direction inferred from recent potentiometric surface maps. The CPT locations were placed on a 100-foot to 200-foot spacing for areal coverage. ECM contracted with Lankelma, Inc., of Richmond, California to advance CPT borings CPT-19 through CPT-32 and the associated Hydropunch° sample borings at the locations shown on Figure 2. The procedures followed in the field are discussed in Section 3. 3 PROCEDURES ECM conducted all field work in accordance with the approved M-10A Investigation Work PIan5, submitted to the RWQCB on June 11, 2010 and approved in a letter dated August 2, 2010. All drilling and sampling efforts were directed by an experienced field geologist, under the supervision of a California-licensed professional geologist. 3.1 FIELD PREPARATION The following sections provide a summary of activities completed prior to commencing drilling operations. 3.1.1 PERMITTING Prior to drilling, ECM obtained soil boring permits (Appendix A) from the San Joaquin County Environmental Health Department (EHD). In addition, ECM obtained a City of Ripon Encroachment Permit (Appendix A) for all CPT boring locations proposed in City of Ripon right-of-ways (e.g., city streets, alleys and city-owned property). 3.1.2 ACCESS ECM proposed one CPT boring (CPT-25) that required an access agreement on private property. CPT-25 was sited on the property located at 212 East Main Street. The owner of the property (occupied by Ripon Auto Body) granted access to ECM to conduct the field investigation. 3.1.3 TRAFFIC CONTROL PLAN ECM obtained a traffic control plan from Safe T Lite of Modesto Inc. (Safe T Lite) as a requirement of the City of Ripon Encroachment Permit application. ECM followed all g CPT borings CPT-1 through CPT-18 were drilled in 2005 by Geomatrix. 4