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TC ASSOCIATES I N C . conducted. ATC evaluated contaminant migration potential of affected soil and groundwater at the site using the EPA's BIOSCREEN (v.1.4) software program. The results of the computer modeling indicated the petroleum impacted soil and groundwater at the site do not appear to be an immediate and significant threat to human health or the environment. The computer modeling results are presented in ATC's Addendum to Additional Site Evaluation and Request for No Further Action for Fayette Manufacturing Corporation, dated November 4, 2002. 2.0 METHODS AND PROCEDURES `r To evaluate the vertical extent of impacted soil and possible lateral migration of impacted groundwater between wells MW4 and MW5, one cone penetrometer test (CPT) boring was advanced immediately adjacent to the former UST locations and three GeoprobeO borings were advanced between wells MW4 and MW5. The soil borings were grouted to the surface with neat cement after samples of soil and groundwater had been collected. Field activities were performed in accordance with ATC's Workplan for Additional Subsurface Investigation at Fayette Manufacturing Corporation Site, 7675 West Eleventh Street, Tracy, California, dated March 4, 2004. This workplan was approved by EHD on March 11, 2004. 2.1 Soil Boring Advancement and Samplin1l ....✓ Drilling was conducted on April 5, 2004, by Fisch Environmental (State C57 license no. 683865) utilizing a Geoprobe0 drill rig. Soil borings GPI, GP2, and GP3 were advanced to approximately 16 feet bgs to a sand interval below the first encountered groundwater. Soil samples were collected at five-foot intervals or significant changes in lithology using a 1-inch diameter acetate sleeve. A photoionization detection meter (PID) was used as a field-screening device for the detection of petroleum hydrocarbon vapors. A field geologist logged soil samples utilizing the Unified Soil Classification System. Descriptions of soil types encountered and sample collection intervals are included on the boring/well construction logs contained in Appendix A. On April 5, 2004, groundwater samples were collected from borings GPI, GP2, and GP3 at approximate depths of 16 feet bgs. The samples were collected by inserting teflon tubing into the boring and oscillating the tubing up and down. Sample containers were then labeled with sample identification,placed on ice, and shipped under chain-of-custody to Argon Laboratories. �r On April 8, 2004, Gregg In Situ, Inc. advanced a CPT sound boring (CPT-1) immediate downgradient of the former USTs and in the vicinity of MW-3 (refer to Figure 2) to obtain a continuous description of the subsurface lithology. This location was chosen because groundwater samples collected from MW-3 have historically contained the high concentrations of BTEX constituents with respect to samples collected from the other wells. A cone mounted with sensors in the tip was advanced into the ground using direct push rods by Gregg's CPT rig which has a down pressure capacity of approximately 20 tons. The sensors measure the response of the soil to the force of the penetrating cone at five centimeter intervals allowing the subsurface 017861\reports\sum2004.doc 3 1�I