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ii <br /> N . <br /> r Guardino - Crawford Company September 2013 <br />'r 517 West Fremont Street, Stockton <br /> Claim No: 14349 <br /> Most Recent Concentrations of Petroleum Constituents in Groundwater <br /> Sample Sample TPHg Benzene Toluene Ethyl- Xylenes MTBE TBA <br /> Date (pg/L) (pg/L) (pg/L) Benzene (pg/L) (pg/L) (pg/L) <br /> p /L) <br /> MW-1 05/23/13 58,000 24,000 4,200 1 ,600 5,500 32 <10 <br /> MW-2 04/29/11 <50 <0.5 <0. 5 <0. 5 <0.6 < 1 < 10 <br /> MW-3 04/29/11 <50 <0.5 <0 . 5 <0. 5 <0 . 6 < 1 < 10 <br /> MW-4 11 /23/11 <50 <0. 5 <0 . 5 <0.5 <0.6 < 1 < 10 <br /> MW-5 04/29/11 <50 <0. 5 <0. 5 <0 . 5 <0.6 < 1 < 10 <br />'I MW-6 04/29/11 <50 <0.5 <0. 5 <0. 5 <0. 6 < 1 < l0 <br /> MW-7 04/29/11 <50 <0.5 <0. 5 <0. 5 <0. 6 < 1 < 10 <br /> MW-8 04/29/11 <50 <0.5 <0. 5 <0. 5 <0.6 < 1 < 10 <br /> OB-1 05/23/13 29,000 800 160 840 443 < 1 < 10 <br /> i <br /> OB-2 05/23/ 13 <50 <0-5 <0. 5 <0 '5 <<1 17 < 10 <br /> EW-1 05/23/13 110,000 18, 000 16,000 21300 11 ,200 38 <10 <br /> WQO 5 0.15 42 29 17 . 5 17200a <br /> NA: Not Analyzed, Not Applicable or Data Not Available <br /> Ng/L: Micrograms per liter, parts per billion <br /> <: Not detected at or above stated reporting limit <br /> TPHg: Total petroleum hydrocarbons as gasoline <br /> MTBE: Methyl tert-butyl ether <br /> TBA: Tert-butyl alcohol <br /> WQOs: Water Quality Objectives, Regional Water Board Basin Plan <br /> California Department of Public Health, Response Level <br /> Groundwater Trends <br /> Since 1999, 11 groundwater monitoring wells have been installed and monitored. Benzene trends <br /> are shown below: Source Area (MW-1 ) and Downgradient (MW-2) . <br /> Source Area Well <br /> BENZENE Results for MW1 <br /> 45000 <br /> 40000 <br /> 35000 <br /> 30000 <br /> j 25000 - - - - <br /> i <br /> y20000 _ 11�_ - . <br /> 15000 • _�_ <br /> .- <br /> l0000 <br /> 5000 .� � �•^1 ,�, . <br /> 0 � <br /> N41 s <br /> BENZENE + +++ Trend <br /> Page 8 of 12 <br />