15 ATTACHMENT 9 - Laserfiche WebLink

Project No. 9929.G Geotechnical Investigation/Vineyard Avenue, Pleasanton 8 August 2003 64. All aggregate base material placed subsequently should also be compacted to a minimum relative compaction of 95% based on the ASTM D1557-91 Test Procedure. The construction of the pavement in the pavement areas should conform to the requirements set forth by the latest Standard Specifications of the Department of Transportation of the State of California and/or City of Pleasanton, Department of Public Works. 65. If planter areas are provided within or immediately adjacent to the pavement areas, provisions should be made to control irrigation water from entering the pavement subgrade. Water entering the pavement section at subgrade level, which does not have a means for discharge, could cause softening of this zone and, subsequently, pavement failure will occur. 66. In order to mitigate this condition, it is recommended that the subgrade beneath curb and gutter be graded such that it has a positive fall towards the catch basins where a 2-foot long subdrain will discharge any accumulated water into the catch basin. The subdrain trench should be a minimum 6 inches deep and consist of a 4-inch perforated solid wall PVC pipe surrounded and underlain by Class II permeable material. The inlet portion of the subdrain pipe should be capped. Utility Trenches 67. Applicable safety standards require that trenches in excess of 5 feet must be properly shored or that the walls of the trench slope back to provide safety for installation of lines. If trench wall sloping is performed, the inclination should vary with the soil type. The underground contractor should request an opinion from the Soil Engineer as to the type of soil and the resulting inclination. 68. With respect to state-of--the-art construction or local requirements, utility lines are generally bedded with granular materials. These materials can convey surface or subsurface water beneath the structures. It is, therefore, recommended that all utility trenches which possess the potential to transport water be sealed with a compacted impervious cohesive soil material or TERRASE,9RCH, inc. Page 29 of 53