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1 <br /> r. <br /> Lj <br /> �1,,Clayton <br /> 1.0 INTRODUCTION <br /> Clayton Group Services, Inc. ("Clayton") has prepared this report on behalf of Shell Oil <br /> Products Company(Shell) to present the information gathered during recent <br /> investigations of the former Shell Oil Central Valley Crude Pipelines referenced above. <br /> This summary report documents these activities. <br /> 2.0 SITE BACKGROUND <br /> An approximately 5,200-foot lineal section of the pipeline route crossed the northeastern <br /> comer of Parcel 209-450-02, the northeastern portion of Parcel 209450-04, the north and <br /> central portions of Parcel 209-450-111 the central portion of Parcel 209-450-12, and the <br /> southwestern portion of Parcel 209-4 (the site),which is located north of Grant Line <br /> Road and west of Mountain House Parkway, northwest of Tracy, California(Figure 1). <br /> shell operated two pipelines, one 8-inch diameter and one 10-inch diameter, which <br /> k ,carried crude oil from the Central Valley to the Bay Area. These lines reportedly <br /> emoved from the property during the 1960s. The pipelines ran in a northwest-southeast <br /> direction through farmed properties and were buried at an average depth of <br /> approximately four to five feet below ground surface (bgs). <br /> Parcels 209-450-02, 209-450-04 and 209-45-11 are currently owned by Trimark <br /> Communities (Trimark) and are awaiting construction into a residential community in the <br /> development known as Mountain House. Parcel 209-45-12 is owned by Ms. Isabel <br /> Oliveira and is used as farmland and a residence. Parcel 209-45-13 is owned by Ms. <br /> Mary Maria Rocha and is also in use as farmland and a residence. These properties are <br /> within the proposed Mountain House development. <br /> Parcels 209-450-02 and Parcel 209-45-04 will be developed into Neighborhood C, which <br /> will be bordered by Great Valley Parkway on the west,Mascot Boulevard to the north, <br /> Central Parkway to the east, and Grant Line Road to the south. Parcels 209-450-11, 209- <br /> 450-12, 209-450-13, and 209-450-14 will be included in Neighborhood D, bounded by <br /> Central Parkway to the west, Mascot Boulevard to the north, Mountain House Parkway to <br /> the east, and Grant Line Road to the south. <br /> hi October of 2004, Clayton performed a series of activities to investigate the soil <br /> conditions along the alignment of the former pipelines in Neighborhoods C and D. These <br /> activities included digging several test pits to verify the location of the former pipeline. <br /> Evidence of the presence of the former pipeline included chips of the pipelines' coating <br /> and variations in soil that filled the pits dug when the pipelines were extracted. Only the <br /> northwestemmost pit contained stained soil and hydrocarbon odor. <br /> Clayton further investigated the soil conditions along the alignment of the former pipeline <br /> by advancing soil borings, generally 8 feet deep, every 25 feet along the alignment. In <br /> I vicinities where evidence of hydrocarbon-impacted soil was observed in these borings, <br /> additional borings were advanced to depths of up to 28 feet below ground surface (bgs)to <br /> further characterize the extent of the impact. <br />