2011-03-14_REVISION - M1977493 (65)

Home Browse Search

CM0001761 Page 7 estimated at approximately 60,000 cy, will be suitable for Dam construction or will not require excavation if existing soils provide a suitable foundation. The actual amount of foundation excavation and reusable soils will depend in part on the Contractor's dewatering and excavation controls program which could have a significant impact on the quantity of borrow soils available for Dam construction. For instance, the unsuitable material excavated from the foundation area may be saturated to the point of sloughing into the excavation. This would not only raise constructability and safety issues, if the sloughing of saturated materials beyond the foundation limits is not controlled, an increased borrow soil quantity will be required to replace the excess sloughing materials. In addition, construction of dikes with borrow material to contain sludge will also reduce the amount of soils available for Dam construction. On the other hand, foundation excavation material may not be overly saturated and have characteristics that, when mixed with other borrow area soils, can be dried or graded to meet the material specifications for various Dam zones. Any excavation that is not represented by the Figure 4 topographic map or subsequent test pit location surveys has not been accounted for in the estimated borrow area soil quantity total. Pre- construction surveys need to be performed to verify the assumption made in the borrow area development and quantity calculations. If the foundation excavation quantity proves to be under-estimated or reusable soils are over- estimated, test pits indicate that additional soils may be obtained from extending the Ten-mile Tunnel Portal Borrow Area deeper or to the north; using Mosquito Fault material if acceptable to CMC; or by developing another borrow area west of the Robinson Lake Reservoir around test pits TP-D8. The Mosquito Fault has not been fully characterized at the time of writing this report and subsequently its development and quantity is not available for this report. CMC reports that a significant quantity of the Mosquito Fault material exists and is accessible at the Climax Pit. 4.2 Alignment and Cross Section The proposed Dam alignment shown on Figure 4 and the cross-sections shown on figures 5 and 6 were selected to provide the storage capacity recommended by Wheeler in their May 3, 1996 c: ynn pn im=\noldam16104rep2.dm 12101196 ..Environmental