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S ECOR - -- Ms. Devra Lewis January 13 , 2005 Page 2 ASSESSMENT ACTIVITIES PIPELINE LOCATION VERIFICATION On January 7, 2005, SECOR and Cruz Brothers (a private utility locator) personnel met at the site with representatives of ChevronTexaco Pipe Line Company (CTPL), Pacific Gas and Electric Company (PG&E) , American Telephone and Telegraph Company (AT&T), and Southwest Bell Companies (SBC) . Although Underground Service Alert (USA) was contacted 48 hours prior to the site visit and a "field-meet' was requested for January 7, 2005 , for all organizations having underground utilities in the site vicinity, no additional utility field representatives attended . SECOR and Cruz Brothers traversed the site vicinity with each of the utility representatives to locate CTPL and PG& E pipelines , and AT&T and SBC transmission lines . While accompanying each of the utility representatives, SECOR utilized a Global Positioning System (GPS) to make periodic location measurements along each of the utilities. In addition , any location where utility representatives indicated a change in the trend of the utility, a location measurement was recorded using the GPS system . For GPS field data point collection and measurements , a Trimble Pathfinder Pro XR GPS unit was used . The unit has 12 channel differential beacon receiver for tracking , carrier phase filtered measurement capabilities, a multibit digitizer, and a circular polarized , omni- directional , hemispherical coverage antenna . The receiver captures data to sub-meter ccuracy-in-real-time-and-then- makes-any-free-to-air-differentiaLcorrections-using o#h a - Coast Guard radio beacon service and a satellite-based augmentation system . Prior to taking field measurements , the GPS unit was set up to use the California Zone 3 0403 coordinates of the US State Plane 1983 coordinate system. Field measurements were then collected by capturing a GPS coordinate for 30 seconds, at one reading per second , with the antenna held at six feet above the point of interest. The data points were exported into AutoCAD , using the GPS Pathfinder Office software. Post processing accuracy of the data has the units reported to the nearest foot. In addition , utility locations relative to streets and property boundaries were also measured using a measuring wheel and tape. This data was compared to GPS data to provide further precision for utility locations . I:\Chevron\302792\Reports\Chevron Pipeline Assessment Report RevA.doe