ARCHIVED REPORTS XR0009294 - Laserfiche WebLink

Home Browse Search

' Cie4 kal reckncc I" g Page 7 ' Site Charactenzation Report Project No 724 2 May 9, 2006 ' o A 3 foot thick silty sand to sandy silt unit is present at 32 feet bgs that is underlain by sandy silt, sand and gravelly sand units extending from 35 —45 feet bgs ' o The ten foot thick sandy units are underlain by silty, clayey and fine grained layers from 45 — 68 feet bgs These fine grained units are followed by four feet of sand to clayey sand units ' o The remainder of the borehole consisted of silty sand to sand units from 72 to 74 5 feet o A soil sample from 32 feet bgs was identified as a medium to coarse grained, ' brown, wet sand by the field geologist This data correlates fairly to the CPT log that shows the interval as a silty sand to sandy silt ' • CPT-2 The CPT log shows primarily fine grained units extending to the total depth of 68 feet bgs o The log shows fine grained units to 25 feet bgs, with a one foot thick silt layer at 4 feet bgs These soils are underlain by silty sand to sandy silt, and sand units to 29 feet bgs ' o Clays are present from 29 — 32 feet bgs o The soils from 32 — 46 feet are interbedded fine grained units with some sands, silty or clayey sand layers that generally do not exceed 1 feet in thickness o The remainder of the borehole encountered more fine grained units from 46 to 68 feet bgs o A soil sample from 27 feet bgs was identified as a fine to coarse grained, slightly ' moist sand by the field geologist This layer transitioned downward to a brown to grey, slightly moist, firm, clayey silt with some iron oxide staining at 28 feet This data correlates fairly to the CPT log that shows the interval as a silty sand to sandy silt unit transitioning to a sand to silty sand and then clayey silt to silty clay units • CPT-3 The CPT log shows primarily fine grained units extending to the total depth of 70 5 feet bgs o Fine grained units are present from the surface to 23 feet bgs o Five feet of sand to silty sands are noted at 23 to 28 feet bgs and these are underlain by fine grained units from 28 to 69 feet bgs ' o A sand to silty sand unit is present from 69 feet bgs to the CPT boring terminus at 70 5 feet o A soil sample from 30 feet bgs was identified as a brown to grey, moist, sandy ' clayey silt by the field geologist This unit transitioned downward to a very fine grained, brown, moist, silty sand This correlates fairly to the CPT log that shows these depths to be undifferentiated fine grained units ' Figures 4 and 6 provide a geologic interpretation of the units observed in the borehole drill logs See Figure 3 for cross section locations The cross sections include lithologies divided into fine grained units (slits and clays) or coarse grained units (sands and gravels)