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Mr.M. Scott Mansholt—CEMC
<br /> Third Quarter 2005 Groundwater Monitoring and Sampling Report October 25,2005
<br /> Vernalis Pump Station,Vernalis,CA Page 3 of 6
<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-1 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.,under the supervision
<br /> 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
<br /> as diesel(TPHd), and TPH quantified as motor oil(TPHmo)were detected in soil samples from
<br /> SB-3 through SB-8,MW-1, and MW-2. Maximum concentrations of TPHd and TPHmo were
<br /> 9,800 mg/kg and 9,000 mg/kg,respectively. TPH as gasoline (TPHg)were detected in SB-8,
<br /> MW-1, and MW-2, and maximum concentrations were 270 mg/kg. TPHd concentrations were
<br /> also present in groundwater samples collected from MW-2 through MW-4 at a maximum
<br /> concentration of 230 micrograms per liter(gg/L). Approximately 6 inches of separate-phase oil
<br /> (SPO)were present in MW-1;therefore,groundwater from this well was not sampled.
<br /> In October and November of 1998, Geomatrix Consultants sampled groundwater from
<br /> monitoring wells MW-2 through MW-4. TPHd were not detected in any of the samples.
<br /> 2002 Site Investigations. In May of 2002, Gregg Drilling and Testing,Inc.,under the
<br /> supervision of Geomatrix Consultants, advanced six soil borings, SB-9 through SB-14. TPH
<br /> quantified as crude oil(TPHc)were detected in soil samples collected from SB-9, SB-10, and
<br /> SB-14, and the maximum concentration was 27,000 mg/kg. Polynuclear aromatic hydrocarbons
<br /> (PAHs)were also detected in soil samples collected from SB-9, SB-10, and SB-14,with a
<br /> maximum concentration of 7.3 mg/kg. No TPHc or PAHs were detected in soil samples from
<br /> SB-11, SB-12, or SB-13. Very low concentrations of benzene,toluene, ethylbenzene, and
<br /> xylenes (BTEX)were detected in various samples collected from borings SB-9 through SB-14.
<br /> 2003 Site Investigations. In August of 2003,Resonant Sonic International,Inc.,under the
<br /> supervision of Geomatrix Consultants,advanced seven soil borings, SB-15 through SB-21, on
<br /> and around the Bellini property. TPHc were detected in all borings except SB-18. The maximum
<br /> concentration detected was 39,000 mg/kg. Low concentrations of BTEX and PAHs were
<br /> detected in various soil samples collected from these borings. Geomatrix Consultants collected
<br /> grab groundwater samples from soil borings SB-15, SB-17, SB-18,and SB-21. TPHg and BTEX
<br /> were not detected in any of the groundwater samples analyzed. However, TPHd and PAHs were
<br /> detected in all the grab groundwater samples analyzed.
<br /> Arcos Property
<br /> 2003 Site Investigations. In October of 2003, Geomatrix conducted a preliminary soil and
<br /> groundwater investigation at the Arcos property,which was part of the Former Vernalis Pump
<br /> Station,but was not under environmental investigation prior to 2003. The preliminary site
<br /> investigation included review of public records,historical maps, aerial photographs,the
<br /> geophysical survey, evaluation of current property conditions, and subsurface investigation.
<br /> Between October 20 and 28, 2003,Gregg Drilling and Testing, Inc.,under the supervision of
<br /> Geomatrix, advanced 12 soil borings,ASB-1 through ASB-12, on and around the Arcos property.
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