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�� • DCN No.C20-SAI-SSJID-PIPELItE-01-05104 O Science Applications International Corporation An Employee-Owned Company klay 26, 2004 Mr. M. Scott Mansholt Chevron Environmental Management Company P.O Box 6012 San Ramon, California 94583-2324 Subject: Summary of Field Activities South San Joaquin Irrigation District Pipeline Banta Road Tracy, California SAIC No. 06-6102-00-5604-202 Dear Mr. Mansholt: At the request of Chevron Environmental Management Company(ChevronTexaco), Science Applications International Corporation(SAIC)performed excavation oversight of a bore pit for installation of a 30-inch diameter water main being installed by Nolte and Associates,Inc. (Nolte) for the South San Joaquin Irrigation District(SSJID) in Tracy,California (Figure 1). Oversight activities were performed following excavation of petroleum-affected soil encountered north of the Union Pacific Railroad (UPRR)right of way(ROW). The Old Valley Pipeline(OVP) is located south of the UPRR ROW approximately 80 feet from the railroad track as shown on Figure 2. SITE BACKGROUND The SSJID pipeline is a 30-inch diameter water main being constructed beneath the UPRR ROW. The ROW easement is occupied by the Kinder Morgan(KM)petroleum pipeline located approximately 15 feet north of the UPRR. To install the water main beneath the UPRR ROW, Ranger Pipeline excavated a bore-and-jack pit in December 2003 prior to installing equipment used to bore beneath the ROW. On December 11,2003,Ranger Pipeline encountered petroleum- affected soil at an approximate depth of I 1 feet below ground surface(bgs). Excavation activities ceased until the affected soil could be property evaluated. Ranger Pipeline stockpiled the affected soil adjacent to Banta Road pending waste characterization and eventual disposal. On December 12 and 19,2003, Kleinfelder, Inc.(Kleinfelder)collected a total of four soil samples for Nolte. One sample was collected from stockpiled soil excavated at an approximate depth of 12 feet bgs from the southern sidewall of the bore-and-jack pit. Two discrete soil samples were collected from borings advanced in the southern portion of the bore pit at depths of 14 and 19 feet bgs. An additional discrete soil sample was collected from a boring advanced in the northern portion of the bore pit at an approximate depth of 14.5 feet bgs. Nolte reported groundwater to be at approximately 50 feet bgs, and the total depth of the bore pit to be approximately 19 feet bgs. The four soil samples collected were submitted to Sequoia Analytical Laboratories in Sacramento, California, for Total Extractable Petroleum Hydrocarbons(TEPH),Total Purgeable Petroleum Hydrocarbons (TPPH),and benzene,toluene,ethylbenzene,and total xylenes(BTEX) analyses. BTEX concentrations were not detected in three of the four soil samples analyzed. 3800 Watt Avenue, Suite#210, Sacramento, CA 95821 (916)974-8800 •Fax:(916)974-8830