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Mr Ron Rowe co Page 2 of 5 I ' GROUNDWATER ACTiVIT>fES Groundwater Monitoring and Sampling Groundwater monitoring was conducted on February 2, 2000 Depth to groundwater was ' measured in wells MW1 through MW 10 and MW13) and subtracted from the wellhead elevations to determine groundwater elevation Monitoi ing wells MW 11 and MW 12 were not accessible The depth to groundwater was also measured in vapor wells VW 1 and VW3 through VW6 Wellhead elevations have not been determined for the vapor wells Water levels rose an average of 0 92 feet since last monitored on November 18, 1999 Groundwater flow was generally ' northeasterly with a gradient averaging approximately 0 003 feet per foot A groundwater gradient map generated using the February 2, 2000 monitoring data is shown on Figure 2 Recent groundwater monitoring data are summarized in Table 1 Monitoring logs and well construction information are included in Attachment A On February 2, 3 and 4, 2000 Ground Zero collected groundwater samples from groundwater ' monitoring wells MW 1 through MW 10 and MW13), and vapor wells VW 1 and VW3 through VW6 At least three well casing volumes were purged from each well prior to sampling Physical parameters (pH, conductivity, tempei atut e) wet e monitoi ed during purging and allowed to stabilize prior to sampling Samples wei e collected sifter groundwater recharged to 100% of the original level Purged water was contained in 55-gallon drums approved by the Department of Transportation and stored onsite in a locked enclosure Purge logs are included in Attachment A 1 Samples were placed on ice and transpoited under chain of custody to Argon Laboratories (DHS #2359) Samples were analyzed foi TPHg using modified EPA method 8415 and BTEX using ' EPA method 8020 Additional sample mat ix collected from monitoring wells MW 1 through MW10, and MW13 and vapor wells VW1, and VW3 through VW6 was analyzed for oxygenates ' using modified EPA method 8260 Analytical i esults for TPHg, BTEX and MTBE are summarized in Table 2, oxygenate results are summarized in Table 3 Attachment B contains laboratory reports and chain of custody documentation ' Groundwater Analytical Results ' Groundwater Monitoring Wells The groundwater surface was above the top of the screened intervals in all monitoring wells except MW2 and MW13 Petroleum hydiocaibons weie detected in groundwater samples ' collected from all monitoring wells except MW 10 (wells MW 11 and MW 12 which historically have been non-detect for petroleum hydi ocai bons wet e inaccessible) The highest concentrations of TPHg and BTEX were detected in samples collected from wells MW4 and MW13 Although increases relative to November 1999 were recorded in samples from some wells, hydrocarbon concentrations in general remained stable in wells affected by the onsite release rockk mrl i gm2000 i �