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C CONESTOGA-ROVERS Ms. Victoria McCartney &ASSOCIATES October 1, 2007 PROPOSED SCOPE OF WORK CRA proposes advancing three soil borings using a direct push rig and collecting soil vapor samples for analysis. The vapor concentrations will be compared to the CHHSLs and/or Region 2 ESLs for soil vapor. The soil vapor borings will be advanced to approximately 6 feet fbg. Actual locations and depths may be changed in the field depending on site conditions. The locations of the proposed borings are indicated on Figure 2. CRA's standard field procedures for soil borings and soil vapor sampling are presented as Attachment B. Underground Utility Location: CRA will notify Underground Service Alert prior to scheduled work to clear the boring locations with utility companies. A private utility line locator will be contracted to additionally clear the boring locations of utility lines prior to sampling. Site Health and Safety Plan: CRA will prepare a site safety plan to inform site workers of known hazards and to provide health and safety guidance. The plan will be kept on-site at all times during field activities and signed by all site workers and site visitors. - Permits: CRA will obtain the necessary permits from the EHD prior to beginning field operations. A minimum of 48 hours notice will be given to the EHD prior to soil boring and vapor sampling activities. Soil Vapor Borings: CRA proposes to advance three borings and collect soil vapor samples from the proposed soil vapor boring locations shown on Figure 2. The total depth of each boring will be approximately 6 fbg. The final locations of the borings will be based on site and utility constraints as evaluated in the field. Soil Vapor Sampling: Soil vapor sample collection will not be scheduled until after a minimum of five consecutive significantly precipitation-free days (:50.5 inches of rain). The service station manager will be asked to discontinue any on-site watering for five days prior to soil vapor sample collection. A generalized schematic of the soil vapor sampling apparatus is presented as Figure B in Attachment B.Samples will be collected using a 1- liter SUMMATM canister connected to the sampling tubing at each vapor point. Prior to collecting soil vapor samples, the initial vacuum of the canister will be measured and recorded on the chain of custody form (this should be approximately 30 inches of mercury [Hg]). The vacuum of the SUMMA TM canister will be used to draw the soil vapor through the flow controller until a negative pressure of approximately 5 inches of Hg is observed on the vacuum gauge. This is the residual vacuum and this measurement should be recorded on the chain of custody form. With the flow controller set at approximately 167 ml/minute, sample collection should take approximately 5 to 10 minutes. 4 Worldwide Engineering,Environmental,Construction,and IT Services