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CitologtCalTtclrirfcslxc. Page 7 Revised Site Conceptual Model Report k Project No.507.2' April 3,2008 �Vk i ❑ Silt layers are present at 9 — 13 feet bgs beneath the clays. The silts are moist and brown to olive in color. Atl 1 feet bgs the color changes to olive with white, caliche like horizontal fractures present (no effervescence with HCl application). ❑ Below these silts, clayey sands are present from 13 — 15 feet bgs. These sands are very fine grained, brown iii color, moist and have white carbonates veins. Na soil was recovered from the 15 = 16 feet bgs interval due to plugged sampler tip. ❑ At 16- 18 feet bgs there is a grey clay unit with white carbonate veins as above. ❑ ,From 18 — 34 feet bgs there are sand units of varying grain size and degrees of grading. The sands range fro very fine to coarse grain in size, are light to dark grey in color, and are moist to saturated. All of the soils in this interval have a strong gasoline odor. In the bottom of this interval, 32 — 34 feet bgs, there are 1/a-V2" thick blue-green colored fine sand lenses in a coarse, grey sand matrix. ❑ Below:the sands the lithology returned to clays at 34 feet bgs. The clays at this depth are grey, with a single 1" thick, coarse sand layer similar to sands above. ❑ At 35 feet to the boring terminus at 36 feet bgs a silt layer was encountered. The silts are grey in color, moist and have whine carbonate veins. Boring SB_91 The subsurface in the vicinity of borehole SB-9 is characterized by alternating layers of G sands, silts and clays very similar to'the other borings but with more sand evident at depth: _ ❑ The top three feet in this location is fill material characterized by red brick fragments and grey road base material.l' ❑ At 3 feet bgs a brown slightly $ m moist,st, silty clay is present that contains lmm thick I white, carbonate lamina. The silty clay continues to a depth of 5 feet bgs but the color changed to black then greywith a hydrogen sulfide (rotten egg) odor. ❑ More claywas encountered at 5 feet bgs but the grey, slightly most soil had a distinct petroleum odor at this level rather than the sulfide odor above. ❑ The clay was underlain by a.,silty clay present at 10 feet bgs. This dark grey, slightly moist soil contained white carbonate veins and a strong petroleum odor. ❑ At 11 feet bgs the clays transitioned to a brown color with prominent white carbonate veins and strong odor as above. i ❑ From 15 — 23 feet bgs there are sand units of varying grain size and degrees of grading. The sands range from very fine to medium grain in size, are light grey to dark in'color, and are moist to saturated. All of the soils in this interval have a strong petroleum odor. o At 23 feet bgs silty clay units are present. The clays are grey, moist and have a strong petroleum odor. ❑ From 27 - 31 feet bgs silt/sandy silt units are present. The slits are grey,moist or wet and have a strong petroleum odor. ❑ From 31 feet bgs to the boring terminus at 36 feet bgs there are sand units of varying grain size and degrees of grading. The sands ranges from very fine to medium grain in size,!are light grey to dark in color, and are moist to saturated. All of the soils in 't this interval have a strong petroleum odor. . .. J S y 1Ir J 1