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Work Plan—PEA Page 3 Former Haley Flying Service GPE Project 474.2 2.0 DATA COLLECTION This section describes the rationale and methods that will be used to obtain the samples and laboratory analytical information to be used in the completion of the second addendum to the PEA. 2.1 Field Work Groundwater samples will be collected and tested from at least three Geo-Probe borings at specific points on the north side of the irrigation ditch which forms the north boundary of the Haley site. Depending on the sample results, additional boring sites may also be selected for laboratory testing. In a separate mobilization, a hollow stem auger drilling rig will be used to drill at least three borings to be converted to groundwater monitoring wells. 2.2 Geo-Probe Sampling Strategy The regional direction of groundwater flow in this area is in a northerly direction, although the precise local direction of flow has not been determined. In an attempt to obtain representative groundwater samples in the down-gradient position, a grid of nine borings, or such lesser number as time allows, will be installed. The Geo-Probe borings will be installed in the empty irrigation ditch, and in a vacant portion of a cultivated field on the north side of the irrigation ditch, which forms the north line of the Haley property (see attached site map). These positions will be northwest, north, and northeast of the area of the most intense pesticide contamination. The purpose of these borings is to assess whether groundwater affected by the pesticide contamination on the Haley site has migrated through the soil to affect the adjacent parcel. An additional boring will be located in the most intensely contaminated area near the east end of the washout pit on the Haley property. The purpose of this boring is to collect soil samples for geotechnical analysis needed for possible future bioremediation. The Geo-Probe soil borings (designated B-9 to B-17?) will be advanced to a depth sufficient to penetrate the groundwater surface, and a sample of the shallow groundwater will be collected from each of these borings. The total depth of the borings is expected to be about 12 to 16 feet. In addition, continuous soil cores will be collected from each Geo-Probe boring. Soil samples from the surface and from a depth of about 6 feet below the surface will be collected for laboratory analysis. These samples are intended to test whether organo chlorine pesticides have impacted the surface soil, and if it has, whether pesticides have leached into the sub-surface. The soil and groundwater samples from all borings will be transported to the laboratory, but only those from B-9 through B-11 will be subjected to immediate laboratory analytical testing. Samples from the other borings on the north side of the irrigation ditch will be held pending the outcome of the initial analytical results. If no pesticides are detected in the southern row of borings, no additional testing will be requested. If, on the other hand, 2937 Veneman Avenue, Suite B240 Geo-Phase Environmental Inc. Phone: (209)569-0293 Modesto, Ca 95356 Fax: (209)569-0295