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Work Plan for Additional Site Assessment
<br /> 1022 Frontage Road,Ripon,California
<br /> CAM B R I A July 25,2006
<br /> May 2004: In May 2004,TEC Accutite removed one 1,000-gallon,steel waste oil UST. Soil samples
<br /> TPI and TP2 were collected by Cambria during the waste oil UST removal activities. No TPHg,
<br /> benzene,fuel oxygenates,volatile organic compounds(VOCs),or poly-chlorinated biphenyls(PCBs)
<br /> were detected. All leaking underground fuel tank (LUFT) metal concentrations appeared to be
<br /> background concentrations. TPHd was detected at concentrations of 4.0 mg/kg(TP1)and 160 mg/kg
<br /> (TP2). No estimate of the amount of soil excavated was provided.
<br /> May 2005: In May 2005, TEC Accutite removed or closed in place the piping related to the former
<br /> waste oil UST. Soil samples WO1 through WO4 were collected by TEC Accutite during the waste
<br /> oil piping removal activities. No benzene, fuel oxygenates, or PCBs were detected. TPHd was
<br /> detected in soil samples WO1, WO3, and WO4 at concentrations of 3, 234, and 17,600 mg/kg,
<br /> respectively. No VOCs were detected,except for 1,3,5-trimethylbenzene(1,3,5-TMB)(2.76 mg/kg),
<br /> 1,2,4-TMB(1.03 mg/kg),and sec-b4tyl benzene(0.761 mg/kg). No semi-volatile organic compounds
<br /> (SVOCs)were detected,except foi naphthalene(2.74 mg/kg)and 2-methylnaphthalene(6.52 mg/kg)
<br /> in soil sample WO4. All LUFT mLtal concentrations appear to represent background concentrations,
<br /> except for 392 mg/kg zinc,detectem soil sample WO3 at 3 ft bgs. No estimate of the amount of soil
<br /> excavated was provided. �41,rd 4V4 edh ! 6a X 1 r.4cs'� +o Gn-c- rnG�i� 8�
<br /> August 2005:In August 2005,Cambria installed monitoring well MW-10 and air sparging well AS-1,
<br /> and advanced soil boring B-18. Well MW-10 was installed to delineate the extent of impacted
<br /> groundwater west of well MW-9. Well AS-1 was installed to conduct a soil vapor extraction/air
<br /> sparging (SVE/AS) pilot test. Soil boring B-18 was advanced near the former USTs to vertically
<br /> delineate impacted soil and groundwater in the source area.'No petroleum hydrocarbons were detected
<br /> in soil samples collected from well MW-10' Elevated petroleum hydrocarbon concentrations were
<br /> detected in the soil sample collected from boring B-18 at 21 ft bgs; however, no petroleum
<br /> hydrocarbons were detected in soil samples collected at 36, 46, and 51 ft bgs in boring B-18. On
<br /> August 31,2005,the groundwater sample collected from well MW-10 contained 57µg/L TPHd and
<br /> 750 gg/L MTBE. Hydropunch groundwater samples were collected from boring B-18 at 30,45,and
<br /> 60"ft bgs and petroleum hydrocarbons were detected in all three samples.'/Inboring B-18 TPHd and
<br /> TPHg groundwater concentrations increased with depth,low BTEX concentrations were detected in
<br /> all three samples,and MTBE concentrations were lower in the two samples collected below the 30 ft
<br /> bgs sample.
<br /> September 2005:In September 2005,Cambria conducted a SVE and a SVE/AS test using well EW-1
<br /> - MW-1
<br /> as a vapor extraction well,well AS-1 as an air sparge well,and wells MW-2,MW-7,MW-9,and MW-
<br /> 10 as observation wells. The effective radius of vacuum influence was determined to be
<br /> 2-
<br /> approximately
<br /> approximately 75 feet for both SVE and combined SVE/AS. The maximum flow rates of 121 cfm and
<br /> V�
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