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F am <br /> am <br /> MMWFr1ff`e� <br /> From Science to Solutions <br /> HPP-BTR MP#204.4 <br /> Vernalis Pump Station <br /> Reports <br /> Accession#06102.20080918.001 <br /> September 26, 2008 <br /> Mr. M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> P.O. Box 6012 <br /> San Ramon, California 94583-0712 <br /> Subject: Second Semi-Annual 2008 Groundwater Monitoring and Sampling Report <br /> Vernalis Pump Station <br /> 35500 Welty Road <br /> Vernalis, California <br /> Dear Mr. Mansholt: <br /> Science Applications International Corporation(SAIC)prepared this report at the request of Chevron <br /> Environmental Management Company(CEMC)to summarize groundwater monitoring and sampling <br /> activities conducted at the Vernalis Pump Station site(the site)in Vernalis, California(Figure 1). This <br /> report summarizes the second quarter 2008 sampling event for wells MW-6 and MW-7 and the third <br /> quarter 2008 sampling event for wells MW-I through MW-7. The groundwater monitoring and sampling <br /> program at the site was initiated at the request of the California Regional Water Quality Control Board— <br /> Central Valley Region(RWQCB)to characterize the extent of affected groundwater from operation of the <br /> former Old Valley Pipeline(OVP) system. The RWQCB concurred with SAIC recommendations to <br /> reduce the sampling frequency for on-site wells MW-1 through MW-5 from a quarterly to semi-annual <br /> basis, and to monitor off-site wells MW-6 and MW-7 (located on the Bogetti property)on a quarterly <br /> basis. Wells MW-6 and MW-7 were abandoned on August 24 and 25,2008, shortly after the third quarter <br /> sampling event. Five groundwater monitoring wells(MW-1 through MW-5)are currently utilized to <br /> evaluate hydrologic and water-quality conditions at the site. Site features and the locations of site <br /> monitoring wells are shown on Figure 2. <br /> BACKGROUND <br /> SITE DESCRIPTION AND USE <br /> The site is located at 35500 Welty Road,Vernalis, San Joaquin and Stanislaus counties, California <br /> (Figure 1). The former pump station consists of the Bellini property(formerly known as the Roberts <br /> property)and the Arcos property. The Bellini property is on the northern part of the site, and the Arcos <br /> property is on the southern part of the site(Figure 2). The Bellini property is a triangular-shaped, <br /> 5.73-acre vacant lot. The Arcos property is irregularly shaped and is currently used as a storage facility <br /> for equipment and materials. A residence and an office are also located on the Arcos property. The <br /> former pump station site is in a rural and light-industrial area and is bordered by Welty Road on the west, <br /> Union Pacific Rail Road(UPRR)tracks and Highway 33 on the northwest, light-industrial facilities on <br /> the southeast, and agricultural areas on the south. Kinder Morgan Energy Partners,L.P. (KM)currently <br /> maintains a high-pressure,petroleum-product pipeline near the site that transports gasoline,jet fuel, and <br /> diesel. The KM pipeline is located within the UPRR right of way(ROW). A 1995 Environmental Site <br /> Assessment determined that the KM pipeline was installed approximately 4 to 5 feet below ground <br /> Science Applications International Corporation <br /> 3800 Watt Avenue I Suite#210/Sacramento,CA 95821 /tel:(916)974-8800/fax:(916)979-3735 1 saic.com <br />