ARCHIVED REPORTS_XR0010774 - Laserfiche WebLink

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. A S S O C I A T E S I N C Results Laboratory analyses detected concentrations of TPHg at 7,600 parts per billion (ppb), benzene at 9 4 ppb, toluene at 8 2 ppb, ethylbenzene at 77 ppb, and xylenes at 41 ppb in the sample collected from well MW4 The sample from MW4 contained no detectable concentrations of MTBE Groundwater samples collected from well MW3 and from the Supply Well contained no detectable concentrations of TPHg, BTEX, or MTBE These analytical results are generally consistent with historical levels Analytical results are summarized in Table 1 Laboratory reports and chain-of-custody documentation are presented in Attachment 2 Recommendations Based on results from the Fourth Quarter 2000 groundwater monitoring event, ATC recommends conducting First Quarter 2001 groundwater monitoring in March 2001 ATC additionally recommends performing a groundwater extraction pilot test to investigate groundwater extraction as a remedial alternative for the subject site, as discussed below • WORKPLAN FOR GROUNDWATER EXTRACTION PILOT TEST Objectives and Scope of Work ATC proposes to perform a 48-hour, low-rate pump test from monitoring well MW4 The objective of the pump test is to determine whether or not groundwater extraction will lower the concentrations of petroleum hydrocarbon constituents to acceptable levels over a reasonable time period 48-Hour Groundwater Extraction Test ATC will notify PHS/EHD at least 48 hours prior to performing any fieldwork Prior to beginning the pump test, ATC personnel will measure depth to water in all on-site wells and will collect one groundwater sample from well MW4 ATC will also collect one groundwater sample from well MW4 mid-way through the test and one sample after the 48-hour pump test has been completed The groundwater samples will be placed on ice and transported under cham-of-custody to Argon Laboratories Samples will be analyzed for TPHg and BTEX by EPA method 8015/8020 and for MTBE by EPA Method 8020 If MTBE is detected in any groundwater samples by EPA Method 8020, the sample will be analyzed for oxygenate fuel additives by EPA Method 8260 to confirm the results . A pump equipped with a flow meter, totalizer, and discharge hose will be installed into well MW4 During the test, ATC will also place transducers in well MW4 and in observation wells w 1625821quart1yl4gr-2000 doc 5