ARCHIVED REPORTS XR0000233 - Laserfiche WebLink

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"Analytical comments for METHOD 8015_W DSL LL, SAMPLE 510737-002A(MW-11), S10737- 004A (MW-9), S10737-020A (VM-1), 510737-022A (MW-14), S10737-024A (VM-2) Sample contains hydrocarbons that do not match the diesel pattern However, quantification is based on a diesel standard " Benzene was detected in groundwater samples collected from wells MW-14, VM-1 and VM-2 at concentrations of 120, 1,400, and 8,000 pg/l, respectively Toluene, ethylbenzene and total xylenes were also detected in wells MW-14, VM-1 and VM-2 at concentrations ranging from 12 (VM-1 - toluene) to 1,200 (VM-2 - ethylbenzene) µg/l FOCs were not detected above laboratory method detection limits in each of the groundwater samples collected TPHg, TPHd and benzene concentrations for the Second Quarter - 2002 monitoring event are depicted on Figure 3, Petroleum Hydrocarbons in Groundwater-July 2002 Eto as etected m the trip blank at a concentration of 140 µg11 Benzene, toluene, ethylbe xylenes were also detected in the trip blank at respective concentrations of 2 2, 16, 2 7 and The trip blank was analyzed immediately following the sample from well VM-2, which had concentrations of TPI-Ig and BTEX, therefore, the impacts noted for the trip blank are likely sidual hydrocarbons from VM-2 CONCLUSIONS AND RECOMMENDATIONS The highest concentrations of dissolved phase petroleum hydrocarbons appear to be limited to the immediate vicinity of the former UST excavation area (monitoring wells MW-14, VM-1 and VM-2) Geocon recommends that quarterly groundwater monitoring continue at the Site to evaluate seasonal trends in groundwater elevation and contaminant concentrations in the vicinity of the former UST locations The next groundwater monitoring event is scheduled for September 2002 If there are any questions concerning the contents of this report, or if Geocon may be of further service,please contact the undersigned at your convenience Sincerely, iGEOCON CONSULTANTS,I JV HAFy��2 ' etTcfi,�' CE s�O.� �� * Rebecca L Silva, REA ro] anager Fj�p.41 �2 Project Scientist ' RLS JE3 krc E Ory,1-�O� OF CA ' (5) Addressee Attachments Figure 1, Vicinity Map ' Figure 2, Groundwater Elevation Map -July 2002 Figure 3, Petroleum Hydrocarbons in Groundwater -July 2002 Table 1, Summary of Groundwater Elevation and Analytical Data Appendix A, Summary of Historical Groundwater Analytical Data Appendix B, Monitoring Well Sampling Data Sheets Appendix C, Laboratory Reports and Chain of Custody Records Project No 58475-06-24A -3- September 11,2002