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i 2.4 Monitoring Well Installation On June 1, 1992, a groundwater monitoring well (MW-1) was installed immediately north of the former tank excavation. A water sample was collected from the well and analyzed for TPH as gasoline and diesel and volatile aromatics (BTE&X). Petroleum hydrocarbons were detected in the water sample and the PHS/EHD required further groundwater assessment. 1 Soil samples collected from MW-1 indicated that a small volume of petroleum hydrocarbons remained in the soil at depths of 35, 40 and 45 feet. Toluene was detected in each sample; ' xylenes were detected in sample 131-35. Two additional monitoring wells were installed by GeoAudit on November 12, 1992. One well (MW-3) was installed south of the warehouse, near the southern boundary of the property (near the Manna Pro facility). The other monitoring well (MW-2)was installed east of the former tank excavation. Installation, sampling procedures, and results were described in a report prepared by GeoAudit ("Groundwater Monitoring Well Installation Report", dated January 8, 1993). No petroleum hydrocarbons were detected in soil samples from MW-2 or MW-3. On June 17, 1993, two additional monitoring wells were installed on the Cutter Lumber property to the north of monitoring well MW-1. MW-4 was installed near the southeast corner of the Cutter Lumber office, north-northeast of monitoring well MW-1; MW-5 was installed at the west edge of the property, northwest of monitoring well MW-1. Installation, M sampling procedures and results were described in the Groundwater Monitoring Well Installation and Sampling Report, dated June 1993. No petroleum hydrocarbons were detected in soil samples from MW-4 or MW-5. 2.5 Groundwater Monitoring Groundwater monitoring at this site began in June 1992, following installation of MW-1.The monitoring program was performed on a semi-annual basis through June 1993. Since then, monitoring has been conducted quarterly. The most recent monitoring is the eighth time ' that groundwater data have been collected at the site. The groundwater depth is measured in all wells and samples are collected from MW-1, MW- 4, and MW-5 during each event. No petroleum hydrocarbons were detected in MW-2 or MW-3 when they were installed in November 1992 or during the June 1993 monitoring. MW-2 and MW-3 are upgradient of the former UST location and are believed to be beyond ' the limits of groundwater contamination. Therefore, groundwater samples are not required by the PHS/EHD to be collected from these wells. 1 2.5.1 Groundwater Depth and Gradient The depth-to-groundwater at the site rose from approximately 42 feet in November of 1992 peo6gnl Audit S.rv— 1n1. 4 WWen L'Et QA6'12.9V1.10 i i