15 ATTACHMENT 9 - Laserfiche WebLink

Project No. 9929.G Geotechnical Investigation/Vineyard Avenue, Pleasanton 8 August 2003 Keyway Construction 18. Where fills are to be constructed on existing slopes steeper than 6:1 (horizontal to vertical), the surface soils are to be removed and keyways should be provided at the base of the fill and should be a minimum of 15 feet wide, cut into firm natural ground, and sloped back into the hillside at a gradient of no less than 2%. It is estimated that the depth of keyways will be at least 3 feet in depth. Subsequent keyed benches should be placed at vertical intervals no greater than 5 feet and should have a width of no less than 5 feet. The fill embankment could then be constructed by placing engineered fill as specified in the following section. A subsurface drain may need to be constructed at the back base of the key and possibly at additional locations as the filling progresses. The location and quantity of any subdrains will be made as part of final grading plan preparation or in the field by the Soil Engineer during grading. Fill Placement 19. All engineered fill should be placed in lifts not exceeding 8 inches in uncompacted thickness and compacted to the following requirements: Condition Minimum Relative Placed Moisture Content Compaction) Above Optimum Base of keyways 95% 2 to 3% General Fill (to within 10 feet 95% 2to3% of finished design grade) General Fill (upper 10 feet of 90% 2 to 3% design grade) Notes: 1) as determined by ASTM D1557-91 Laboratory Test Procedure 2) The 95% compaction is required in order to minimize the potential for excessive total and differential settlement. TERRASEARCH, inG Page 16 of 53