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lh • Mr Jeffrey Wong Page 5 of 10 Prior to well development, the depth to groundwater was measured in each well and subtracted from the surveyed wellhead elevation to determine groundwater elevation The potentiometric surface ranged from 25 59 feet to 25 62 feet below mean sea level An apparent depression appeared to be located in the vicinity of well MW 1 The average hydraulic gradient was approximately 0 003 ft/ft Depth to water was measured again on February 9, 2001, due to the recent change in the flow direction initially determined prior to installing well MW4 The potentiometric surface ranged from 25 42 feet to 25 44 feet below mean sea level Groundwater now flowed in a north-northeast direction, with a hydraulic gradient of less than one foot per mile Potentiometric surface maps generated using the February 7, 2001 and February 9, 2001 well monitoring data are depicted on Figures 3 and 4 Groundwater monitoring logs are included in Attachment B Groundwater monitoring data are summarized in Table I Subsequent to surveying and measuring initial depth to water, the new wells were developed by surging and bailing until turbidity was minimized Temperature, pH, and electrical conductivity were measured during the well development process Purge water was placed into DOT approved 55-gallon drums, which are currently stored on site pending proper disposal options After 100 % groundwater recovery and parameter stabilization, groundwater samples were collected from each well and placed in an iced cooler for submittal to Argon under chain of custody protocol Analysis consisted of gasoline oxygenate additives, EDB and 1,2 dichloroethane (1,2 DCA) by EPA methods 8015, TPHg and BTEX by EPA methods 8020 and 8260, respectively Well development logs are included in Attachment B 3.5 Cone Penetrometer Testing On April 12, 2001, Gregg Drilling advanced one CPT boring (CPT1) utilizing a 25-ton CPT drill rig, boring within the former tank pit Electric CPT data transmitted from the cone tip provided information on soil behavior by measuring penetration resistance, friction ratio, and pore pressure Correlation of soil behavior to soil type was made electronically, based on a soil classification chart interpreted by Robertson & CampaneIla (1983) A copy of CPT log and raw data are included in Attachment C The CPT location is shown on Figure 2 3.6 Discrete Soil and Groundwater Sampling On April 12 and 13, 2001, Gregg advanced two direct push borings (SB6 and SB7) adjacent to boring CPTI utilizing a 25 ton CPT drill rig to collect discrete soil and groundwater samples A one-foot long Geo Probe° type soil sampler lined with stainless steel sleeves was used to collect soil samples from strata identified from the CPT data, affording soil identification, subjective evaluation for contamination and screening for volatile constituents with a PID Soil samples collected for analysis were sealed, labeled, and immediately placed in an iced cooler for transport and submittal under chain of custody protocol to Argon Analysis consisted of TPHg, BTEX gasoline oxygenate additives, 1,2 DCA, EDB, methanol and ethanol Soil boring locations are shown on Figure 2 Soil boring logs are included in Attachment A . Discrete groundwater samples were collected from boring SB7 within strata identified from CPT data initially with a Simulprobe© sampling tool in order to significantly decrease the chance for dat,tlgrounzelh:uryslwellreport doe