ARCHIVED REPORTS_XR0003778 - Laserfiche WebLink

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laboratory (MCCAMPBELL ANALYTICAL INC. ) under Chain of Custody . (COC) documentation for analysis. The groundwater samples from the three wells had a slight hydrocarbon odor. ANALYTICAL RESULTS The analytical methods are those required in the "Tri-Regional Guidelines" which are directives of the Regional Water Quality Control Board and requested by the SJCEHD. The analyses completed were for Total Petroleum Hydrocarbons, as gasoline (TPHG) ; Benzene, Toluene, Ethylbenzene and Xylene (BTEX) and Methyl-tert-butyl ether (MTBE) via EPA Modified Method 8020/8015. The results of the groundwater samples in ug/L (parts per billion {ppb}) for TPHG, MTBE and BTEX are shown in Table 1. Laboratory Data Sheets with detection limits and a copy of the Chain of Custody (COC) are contained in Appendix B. SUMMARYO CONCLUSIONS AND RECOMMENDATIONS • The calculated gradient is S 81 E or 99 * at 0. 03 ft/ft. This is a generally easterly gradient. The direction and slope have changed from southerly found in the prior calculated gradients. The gradient direction and slope changes are most likely due to the heavy rains and high levels in the local surface waterways. Based on the analytical data from prior quarterly reports, it appears that no detectable concentrations of lead are impacting the groundwater at this site. The groundwater beneath the site has been impacted and heavy gasoline and BTEX contamination were detected in the groundwater samples from MW-1 and MW-2. Lesser concentrations of gasoline and BTEX were detected in the sample from MW-3 . All the wells had actionable levels of TPHG and BTEX. The concentrations of TPHG and BTEX, found in the analysis of groundwater samples collected and analyzed from these wells, have continued to decrease. JPCA recommends continued monitoring of the wells to further evaluate the amount of contamination and consistency of the gradient. . 3