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Mr. M. Scott Mansholt—CEMC
<br /> Fourth Quarter Groundwater Monitoring and Sampling Report and
<br /> 2005 Annual Summary December 22,2005
<br /> Vemalis Pump Station, Vernalis,California Page 3 of 7
<br /> PREVIOUS ENVIRONMENTAL ACTIVITIES
<br /> Bellini Property
<br /> 1994 and 1995 Site Investigations.' Geological Technics, Inc. performed a Preliminary
<br /> Environmental Site Assessment. The site assessment included review of public records, areal
<br /> photographs, on-site reconnaissance, personal interviews, and subsurface investigation.
<br /> On January 20, 1995 Osterberg and Stewart Inc.,under the supervision of Geological Technics
<br /> drilled two soil borings, SB-I and SB-2. Total extractable petroleum hydrocarbons (TEPH)were
<br /> detected in soil samples collected from SB-2 at concentrations ranging from 11,800 milligrams
<br /> per kilogram(mg/kg) to 17,200 mg/kg. In addition, total recoverable petroleum hydrocarbons
<br /> (TRPH)were detected in the soil sample collected from SB-2 at a concentration of 17,600 mg/kg.
<br /> 1998 Site Investigations.° In July of 1998, Gregg Drilling and Testing, Inc. (Gregg Drilling),
<br /> under the supervision of Radian International LLC,drilled six soil borings, SB-2 through SB-8,
<br /> and installed four groundwater monitoring wells, MW-1 through MW-4. Total petroleum
<br /> hydrocarbons quantified as diesel (TPHd), and TPA quantified as motor oil(TPHmo)were
<br /> detected in soil samples from SB-3 through SB-8, MW-1, and MW-2. Maximum concentrations
<br /> of TPHd and TPHmo were 9,800 mg/kg and 9,000 mg/kg, respectively. TPH quantified as
<br /> gasoline(TPHg) were detected in SB-8, MW-1, and MW-2, and maximum concentrations were
<br /> 270 mg/kg. TPHd concentrations were also present in groundwater samples collected from
<br /> MW-2 through MW-4 at a maximum concentration of 230 micrograms per liter(pg/L).
<br /> Approximately 6 inches of separate-phase oil (SPO) were present in MW-1; therefore,
<br /> groundwater from this well was not sampled.
<br /> In October and November of 1998, Geomatrix Consultants, Inc. (Geomatrix) sampled
<br /> groundwater from monitoring wells MW-2 through MW-4. TPHd were not detected in any of the
<br /> samples.
<br /> 2002 Site Investigations.' 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
<br /> detected in soil samples collected from SB-9, SB-10, and SB-14, and the maximum concentration
<br /> was 27,000 mg/kg. Polynuclear aromatic hydrocarbons(PAHs)were also detected in soil
<br /> samples collected from SB-9, SB-10, and SB-14, with a maximum concentration of 7.3 mg/kg.
<br /> No TPHc or PAHs were detected in soil samples from SB-11, SB-12, or SB-13. Very low
<br /> concentrations of benzene,toluene, ethylbenzene, and xylenes(BTEX) were detected in various
<br /> samples collected from borings SB-9 through SB-14.
<br /> 2003 Site Investigation' In August of 2003, Resonant Sonic International, Inc.,under the
<br /> supervision of Geomatrix, advanced seven soil borings, SB-15 through SB-21, on and around the
<br /> Bellini property. TPHc were detected in all borings except SB-18. The maximum concentration
<br /> detected was 39,000 mg/kg. Low concentrations of BTEX and PAHs were detected in various
<br /> soil samples collected from these borings. Geomatrix collected grab groundwater samples from
<br /> soil borings SB-15, SB-17, SB-18, and SB-21. TPHg and BTEX were not detected in any of the
<br /> 3. Geological Technics,Inc.,February 1995,Preliminary Environmental Site Assessment: Vemalis Property, 35500
<br /> Welty Road,Vernalis,California.
<br /> 4. Radian International,Inc.,July 1998,Preliminary Site Investigation Work Plan: Roberts Property.
<br /> 5. Geomatrix Consultants, Inc.,August 2002,Report of Soil and Groundwater Investigation,Former Roberts
<br /> Property,Vemalis,California.
<br /> 6. Geomatrix Consultants,Inc.,January 2004,Report of Soil and Groundwater Investigations,Former Roberts
<br /> Property,Vemalis,California.
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