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. GROUNDWATER MONITORING <br /> On April 9, 1997, a Snuth Technology technician measured the water levels in wells MW-1 <br /> through MW-5, well RW-1, piezometer PZ-1, and vapor wells VW-1, VW-2d, VW-3, VW-4, <br /> VW-5s, and VW-5d The groundwater table was found to be above the top of screen in the <br /> monitoring wells so depth to water was measured in vapor wells to aid in the selection of <br /> additional wells for sampling No floating product was noted in any site well Groundwater <br /> monitoring data are summarized in Table 1 <br /> The depth to water measurements and the elevations of the well casings (Table 1) of wells MW-1 <br /> through MW-5 and RW-1 were used to evaluate the groundwater flow direction and gradient <br /> beneath the site Groundwater elevation beneath the site increased an average of 0 77 feet since <br /> January 23, 1997 The groundwater gradient for April 9, 1997 was not consistent with previous <br /> groundwater gradients which showed groundwater flowed to the east There appears to be <br /> mounding in the vicinity of well MW-2 causing the change in the gradient The groundwater <br /> gradient for April 9, 1997, is depicted on Figure 3 <br /> GROUNDWATER SAMPLING <br /> On April 9, 1997, groundwater samples were collected from wells MW-1, MW-2, MW-3, and <br /> MW-5 for laboratory analyses Since the groundwater table elevation was above the top of <br />. screen in these wells, these samples represent water quality in the area of the screen interval only <br /> A sample was not collected from well MW-4 because historically petroleum hydrocarbons have <br /> been nondetectable in this well To provide water quality at the current water table, groundwater <br /> samples were collected from vapor wells VW-1 and VW-3 which are screened from <br /> approximately 15 to 30 feet below ground surface The field methods used are presented in <br /> Attachment 1 Field purge logs are included in Attachment 2 <br /> Groundwater samples were analyzed by Sequoia Analytical for total purgeable petroleum <br /> hydrocarbons (TPHg) using Environmental Protection Agency (EPA) Method 8015 modified, <br /> total extractable petroleum hydrocarbons (TPHd) using EPA Method 8015 modified, and <br /> benzene, toluene, ethylbenzene, and total xylenes (BTEX) using EPA Method 8020 Copies of <br /> the laboratory reports and chain of custody documentation are included in Attachment 3 <br /> ANALYTICAL RESULTS <br /> Results of laboratory analyses indicated dissolved TPHg was detected in the samples from wells <br /> MW-1, RW-1, and VW-1 at concentrations of 2,200 parts per billion (ppb), 61 ppb, and 29,000 <br /> ppb, respectively No TPHg was detected in any other site monitoring wells Benzene, toluene, <br /> ethylbenzene, and xylenes were detected in wells MW-1 and VW-1 Benzene and toluene <br /> concentrations decreased to nondetectable concentrations this quarter in well MW-5 No other <br /> BTEX constituents were detected in any of the wells TPHd was detected in wells MW-1, MW- <br /> 2, MW-3, MW-5, and VW-1 at concentrations ranging from 58 ppb in MW-2 to 11,000 ppb in <br /> w 194367\9436712Q5R97 doc 2 <br /> • <br /> SMTN <br />