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1 <br />' Aggregate Industries - F Stree[ Site Characterization Report <br />Project Number [001018 PnRn~orr <br />' October 9, 2001 <br />Page 7 <br />• TEPH concentrations observed in the West Wall North End, Bottom #1, and South <br />' Wall Middle assessment samples exceed the TPH Threshold. It should be noted that <br />the Bottom # l soil sample was collected from beneath the groundwater table at a <br />' depth of approximately 13 to 1 ~ feet below grade and the sample was lifted through <br />the apparently impacted groundwater. <br />• Test pits 1 and 2 were completed beyond the extent of the abatement excavation near <br />the West Wall North End and South Wall Middle assessment samples and the sample <br />results appear to indicate that the lateral extent of TEPH contamination in soil is <br />bracketed in those areas. <br />' TEPH concentrations were not observed above the TPH Threshold in the soil samples <br />analyzed from MW-2. Therefore, it appear that the TEPH contamination is bracketed <br />' in the vertical extent. <br />5.2 Groundwater Sample Results <br />' Paragon personnel developed and collected groundwater samples from MW-1 through MW- <br />4 and EW-1 on July 25, 2001. Groundwater samples were collected with disposable bailers <br />' and were transported under standard Paragon chain-of-custody procedures to TLI for BTEX <br />and TEPH analyses. The laboratory results for the groundwater samples collected from the <br />site are summarized on Figure 6 in Appendix A and in Table 3 in Appendix B of this report. <br />' As seen from Figure 6 and Table 3, BTEX and TEPH were not observed above the <br />laboratory detectio^ limits of 0.5 micrograms per liter (µg/L) and 0.5 milligrams per liter <br />' (mg/L) in the groundwater samples collected from MW-1 through MW-4 and EW-l on July <br />25, 2001 with the exception of xylenes which were observed at a concentration of 3.6 µg/L <br />in the sample collected from MW-2. <br />' The; Maximum Contaminant Levels (MCLs) for BTEX are also summarized in Table 3. As <br />seen from Table 3, the MCLs for BTEX are 5.0; 1,000; 680 and 10,000 µg/L, respectively. <br />' Those standards are the statewide interim organic pollutant standards published in "The <br />Basic Standards for Ground Water" Regulation 4l, (5 CCR 1002-41). It should be noted <br />' that TEPH is not regulated by a numeric standard in Colorado at this time. The BTEX <br />concentrations observed in the groundwater samples collected from MW-1 through MW-4 <br />and EW-1 in July 2001 did not exceed the MCLs. <br />6. POTENTIAL IMPACTS <br />' Potential impacts from the diesel-fuel release at the subject site are discussed in this chapter. <br />In general accordance with the risk-assessment process established by the OPS, potential <br />1 <br />1 <br />