ARCHIVED REPORTS XR0000084 - Laserfiche WebLink

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Upon review of the field investigation data, the County requested quarterly monitoring of groundwater at the site and the development of a work plan to define the extent of soil and ' groundwater impacted by hydrocarbon compounds at the site. Subsequent work at the site included completion of quarterly groundwater monitoring events in ' December 1991, March 1992 and June 1992 The results of these monitoring programs are presented as part of the discussion of the current quarter results presented in Section 2 0 of this report ' Additionally, a preliminary remedial plan was developed which focused on removal of remaining fuel piping onsite, remediation of soils onsite by vapor extraction technology and extension of ' the groundwater monitor well field The implementation of elements of this plan occurred in September and October of 1992 as discussed below in Section 3 0. I2.0 QUARTERLY GROUNDWATER MONITORING REPORT This section presents the results of the third quarter monitoring event as well as a compilation ' of monitoring data from prior quarterly monitoring events ' 2.1 Field Activities The third quarter monitoring event was conducted beyond the end of the calendar quarter on October 15 and 19 to allow inclusion of three newly installed monitor wells in the program The new wells (MW-4, MW-5 and MW-6) were installed in mid-September 1992 at locations shown on Figure 2. The installation procedure is detailed further in Section 3 1 2 as part of the ' discussion of the remedial program All six wells were inspected for the presence of floating product and sampled with procedures detailed in the Field Report presented in Appendix A for analysis of TPH-G (Method 8015-M), BTEX (Method 8020), total lead (Method 239 2) and ' fecal coliform (Method 909c) A polyethylene tank was installed on the site to store water generated by the development of the three new wells and the purging of all wells for the current (and future) monitoring events Disposal of the accumulated purge waters will be arranged upon Icompletion of characterization of the total volume accumulated at a future date 2.2 Quarterly Monitoring Results IA summary of the analytical results of the October 1992 groundwater monitoring event is displayed in Table 1 while the complete analytical reports are presented in Appendix B All ' samples are labeled to correspond to the well from which they were taken except for sample W-9 which was a field decontamination ro re check sa am le MW-10 which was a u Ii f nm sam le MW-2 Both of the quality assurance samples were only ' analyzed for BTEX compounds To aid in the interpretation of trends over time, Table 2 presents a chronological record of groundwater monitoring results since the inception of the project I ' VXCIRn51AREG3QTR WP 4 It!!3l42