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Mr. Dave Henry • Project AE5701 June 5, 1998 Page 2 Limited subsurface exploration was subsequently performed by ATC. Four soil borings were advanced, via geoprobe technology, to approximately 10 feet below ground surface (bgs). Photoionization detector (PID) readings in all boring were reported to be 0 parts per million (ppm). Water was encountered at 10 feet bgs (ATC, 1998). Soil samples were collected by ATC from 4.5 to 5.5 feet bgs and 9.5 to 10.5 feet bgs in each boring. Water samples were also collected form each boring. Soil and groundwater samples were submitted for laboratory analysis for: • total petroleum hydrocarbons (TPH) as gasoline (TPHg); • benzene, toluene, ethylbenzene, and total xylenes (BTEX); • TPH as diesel (TPHd); and • five common fuel oxygenates, including Methyl tert-butyl ether (MtBE), using USEPA Method 8260. Based on the results of these analyses, TPHd was identified by ATC as the constituent of concern at the site. The following table depicts the TPHd concentrations reported in the samples collected from these borings: TPHd in Geoprobe Soil and Water Samples Soil Sample at Soil Sample at Distance from 4.5-5' bgs 9.5-10' bgs Water Sample Boring I.D. Excavation(ft.) (TPHd, mg/Kg) (TPHd, mg/Kg) (TPHd, µg/L) SBl 20 1.2 2.1 55 SB2 7 2.7 1.9 ND (<50) SB3 32 1.4 2.0 53 SB4 6 1.8 1.6 58 Scope Groundworks' scope of work associated with the excavation of soils for subsurface utility placement just beyond the present eastern terminus of D'Arcy Parkway consisted of: • sampling water from the dewatering system discharge; • field observations to monitor for the possible presence of petroleum hydrocarbon-impacted soil and/or groundwater; • assessing whether obviously-impacted soil and/or groundwater (based on visual or olfactory evidence and PID readings) were encountered during excavation activities, and if encountered, advising the site representative Groundworks Environmental, Inc. AE5701.DOC