Key Considerations for Phase III
Engineering:
Cost of constructing new bypass tunnels?
Let’s look at the cost of original bypass tunnels:
1955-1957 Cost Estimate:
“Excavation, in all classes, in open cut for diversion tunnels” – $950,370.00 (removal of 316,790.0 cubic yards of material)
“Excavation, all classes, in diversion tunnels” – $3,731,938.20 (removal of 186,596.91 cubic yards of material)
Cost of similar modern projects:
SNWA “Third Straw”: 24′ in diameter, 3 miles,
for $817 million, or $272 million per mile.
Ballpark average for tunneling projects in California:
30′ tunnel costing $20,000 per foot drilled, or $84.4 million per mile.