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Mr.M. Scott Mansholt—CEMC
<br /> Fourth Quarter 2006 Groundwater Monitoring and Sampling Report and
<br /> Annual Summary Report January 12,2007
<br /> ' Vernalis Pump Station Page 3 of 7
<br /> Total extractable petroleum hydrocarbons were detected in soil samples collected from SB-2 at
<br /> concentrations ranging from 11,800 milligrams per kilogram(mg/kg)to 17,200 mg/kg. In addition,total
<br /> recoverable petroleum hydrocarbons were detected in the soil sample collected from SB-2 at a
<br /> concentration of 17,600 mg/kg.
<br /> 1998 Site Investigations.' In July of 1998, Gregg Drilling and Testing, Inc. (Gregg Drilling),under the
<br /> supervision of Radian International LLC, drilled six soil borings, SB-2 through SB-8, and installed four
<br /> groundwater monitoring wells,MW-1 through MW-4. Total petroleum hydrocarbons quantified as diesel
<br /> (TPHd), and TPH quantified as motor oil(TPHmo)were detected in soil samples from SB-3 through
<br /> SB-8,MW-1, and MW-2. Maximum concentrations of TPHd and TPHmo were 9,800 mg/kg and
<br /> 9,000 mg/kg, respectively. TPH quantified as gasoline(TPHg)were detected in SB-8,MW-1, and
<br /> ' MW-2, and maximum concentrations were 270 mg/kg. TPHd concentrations were also present in
<br /> groundwater samples collected from MW-2 through MW-4 at a maximum concentration of
<br /> 230 micrograms per liter(pg/L). Approximately 6 inches of separate-phase oil(SPO)were present in
<br /> MW-1; therefor eroundwater from this well was not sampled.____
<br /> In October and November of 1998,Geomatrix Consultants, Inc. (Geomatrix)sampled groundwater from
<br /> monitoring wells MW-2 through MW-4. TPHd were not detected in any of the samples.
<br /> 2002 Site Investigations.4 In May of 2002, Gregg Drilling,under the supervision of Geomatrix,
<br /> advanced six soil borings, SB-9 through SB-14. TPH quantified as crude oil (TPHc)were detected in soil
<br /> samples collected from SB-9, SB-10, and SB-14, and the maximum concentration was 27,000 mg/kg.
<br /> Polynuclear aromatic hydrocarbons(PAHs)were also detected in soil samples collected from SB-9,
<br /> SB-10, and SB-14,with a maximum concentration of 7.3 mg/kg. No TPHc or PAHs were detected in soil
<br /> samples from SB-11, SB-12, or SB-13. Very low concentrations of benzene,toluene, ethylbenzene,and
<br /> total xylenes(BTEX)were detected in various samples collected from borings SB-9 through SB-14.
<br /> 2003 Site Investigation.5 In August of 2003,Resonant Sonic International,Inc.,under the supervision of
<br /> Geomatrix,advanced seven soil borings, SB-15 through SB-21, on and around the Bellini property.
<br /> ' TPHc were detected in all borings except SB-18. The maximum concentration detected was
<br /> 39,000 mg/kg. Low concentrations of BTEX and PAHs were detected in various soil samples collected
<br /> from these borings. Geomatrix collected grab groundwater samples from soil borings SB-15, SB-17,
<br /> ' SB-18, and SB-21. TPHg and BTEX were not detected in any of the groundwater samples analyzed.
<br /> However, TPHd and PAHs were detected in all the grab groundwater samples analyzed.
<br /> 2005 Investigation.b In May 2005, SAIC advanced six soil borings(SB-22 through SB-36) and three
<br /> ' well borings(MW-5 through MW-7)at the site. The soil and well borings were advanced to various
<br /> depths between 40 and 71.5 feet bgs. Based on the soil chemical analytical results, it appeared the
<br /> affected soil north-northwest,north-northeast, south-southwest, and south-southeast of the former boiler
<br /> house and pump house has been laterally delineated. Based on the grab groundwater chemical analytical
<br /> results,it appeared that affected groundwater is delineated west-northwest of the former pump house and
<br /> boiler house. However, groundwater north-northeast and southeast of the former pump house and boiler
<br /> house appeared to be affected by dissolved-petroleum constituents.
<br /> ' 3. Radian International,Inc., 1998. Preliminary Site Investigation Work Plan:Roberts Property. July.
<br /> 4. Geomatrix Consultants,Inc.,2002. Report of Soil and Groundwater Investigation,Former Roberts Property, Vernalis,
<br /> California. August.
<br /> ' 5. Geomatrix Consultants,Inc.,2004. Report of Soil and Groundwater Investigations,Former Roberts Property, Vernalis,
<br /> California. January.
<br /> 6. SAIC,2005. Soil and Groundwater Evaluation,Draft Analytical Results from May 2005 Investigation, Vernalis Pump
<br /> Station, Vernalis California. June.
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