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N�/F N <br /> f S1 <br /> aril`O <br /> From Science to Solutions <br /> HPP-BTR MP#204.4 <br /> Vernalis Pump Station <br /> Reports <br /> DCN:C20-SAI-Vernalis-PS-01-12836 <br /> October 29, 2007 <br /> Mr. M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> P.O. Box 6012 <br /> San Ramon, California 94583-0712 <br /> Subject: First Semi-Annual 2007 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(SAIL)prepared this report at the request of <br /> Chevron Environmental Management Company(CEMC)to summarize groundwater monitoring <br /> and sampling activities conducted at the Vernalis Pump Station site(the site),Vernalis, California <br /> (Figure 1). The groundwater monitoring and sampling program at the site was initiated at the <br /> request of the California Regional Water Quality Control Board—Central Valley Region <br /> (RWQCB)to characterize the extent of affected groundwater from operation of the former Old <br /> Valley Pipeline (OVP) system. The RWQCB concurred with SAIC recommendations to reduce <br /> the sample frequency from a quarterly to semi-annual events,with the exception of the wells <br /> located on the Bogetti property (MW-6 and MW-7), in a letter dated August 16th,2007. The <br /> RWQCB requested that these wells be monitored and sampled on a quarterly basis until the <br /> down-gradient extent of petroleum-affected groundwater has been characterized. The quarterly <br /> sampling data for wells MW-6 and MW-8 will be reported on a semi-annual basis. This report <br /> presents the results from the first semi-annual 2007 monitoring and sampling event. Seven <br /> groundwater monitoring wells are currently utilized to evaluate hydrologic and water-quality <br /> conditions at the site. Pertinent site features and the locations of site monitoring wells are shown <br /> 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, <br /> California(Figure 1). The former pump station consists of two properties: the Bellini property <br /> (formerly known as the Roberts property)and the Arcos property. The Bellini property is located <br /> on the northern part of the site, and the Arcos property is located on the southern part of the site <br /> (Figure 2). The Bellini property is a triangular shaped, 5.73-acre vacant lot. The Arcos property <br /> is irregularly shaped and is currently used as a storage facility for equipment and materials. A <br /> residence and an office are also located on the Arcos property. The former pump station site is <br /> located in a rural and light-industrial area and is bordered by Welty Road on the west,Union <br /> Pacific Rail Road(UPRR)tracks and Highway 33 on the northwest, light-industrial facilities on <br /> the southeast, and agricultural areas on the south. Currently,Kinder Morgan Energy Partners, <br /> L.P. (KM)maintains a high-pressure,petroleum-product pipeline near the site that transports <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 />