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0 DRAFT 0 <br /> (CGT) Pipelines (A Subsidiary Of PG&E) will comment on the proposed excavation <br /> depths beneath the Chevron Pipeline due to potential stability issues with their adjacent <br /> pipeline. It is also expected that Chevron will provide backfill and compaction services for <br /> their pipeline. <br /> Kleinfelder understands that the top of the Chevron Pipeline is buried approximately 1 to <br /> 2 feet bgs is 18-inches in diameter and that top of the adjacent PG&E Pipeline is buried <br /> approximately 5 feet bgs. Given preliminary soil conditions noted at the site, Kleinfelder <br /> assumes a slope of 1-1/2 to 1 from top of the PG&E Pipline will be acceptable to PG&E. <br /> Given this slope ratio, Kleinfelder estimates approximately 3 feet of soil can be removed <br /> from beneath the Chevron Pipeline at a maximum depth of approximately 6 feet bgs. <br /> Kleinfelder at this time proposes vertical removal of soil from beneath the removed <br /> Chevron Pipeline within the existing trench dimension (approximately 3 feet wide). Due to <br /> safety considerations with their pipeline, CGT Pipelines will have the opportunity to review <br /> this workplan and make a final decision on acceptable slope ratios, trench depths etc. <br /> PG&E Pipeline Easment Area <br /> Kleinfelder understands two PG&E natural gas pipelines run parallel and north of the <br /> Chevron Crude Oil pipeline approximately 25 feet apart. Based on previous site visits by <br /> PG&E personnel, Kleinfelder understands the top of these two pipelines are <br /> approximately 5 feet bgs. Kleinfelder proposes removing the top three feet of soil over <br /> the two pipelines and excavation of soil between the two pipelines. Assuming an <br /> acceptable slope ratio of 1-1/2 to 1, a shallow V-shaped excavation is proposed between <br /> the two pipelines beginning two feet above the top of pipeline with an maximum depth of <br /> 11 feet below original ground surface. As noted above PG&E will have the opportunity to <br /> review this workplan and make a final decision on acceptable slope ratios, trench depths <br /> etc., due to safety considerations with their pipeline. <br /> Confirmation Soil Sampling <br /> Kleinfelder proposes collection of approximately thirty (30) discrete bottom excavation <br /> soil samples based on a 50 foot grid pattern. Kleinfelder estimates the average depths <br /> outside of the pipeline easement areas to be approximately 5 to 13 feet bgs as shown <br /> on Plate 4. It is estimated that approximately 5 additional soil samples within the <br /> pipeline easement area will be needed to evaluate residual petroleum concentrations <br /> left in place in the pipeline easement area. The average depth of bottom soil samples <br /> is estimated at 5 feet in Area B (west and northwest portion of footprint area) and 9 feet <br /> in Area C (central area). Confirmation bottom soil samples are estimated at a depth of <br /> 13 feet bgs in Area D (eastern area). <br /> Kleinfelder proposes collection of approximately twenty four (24) sidewall samples <br /> around the perimeter of the estimated excavation boundaries at 40 to 60 foot intervals <br /> as shown on Plate 4. The interval variances are based partly on proximity to excavation <br /> bottom samples to the estimated sidewall locations. At this time Kleinfelder proposes <br /> the sidewall confirmation sampling depths to be approximately '/2 the estimated total <br /> 44843.T04/STO5R997/DH:ly Page 5 of 14 <br /> ©2005 Kleinfelder, Inc. August 16,2005 <br />