Ten Mile Tunnel in Orange County, Altamonte Tunnel Next?
Drilling under way to study building traffic tunnel to Orange County
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09:56 PM PDT on Wednesday, April 23, 2008
Each day a handful of contractors commute by helicopter from Corona to a remote site in the Cleveland National Forest, sent to find out whether commute times between Riverside and Orange counties can be cut. As they drill deep into the Santa Ana mountainside separating the counties, they'll determine if a proposed tunnel linking Corona and Irvine is possible.
Any decision to build a 10-mile hole through the mountains hinges on the results of the core samples they are digging. Test results should be in the hands of the Riverside County Transportation Commission by late 2009, said commission deputy director John Standiford. A $15.8 million federal grant to examine congestion relief methods in the region funds the drilling and testing.Story continues below
Standiford joked that engineers say anything is possible, but said the soil quality and water levels could deep-six the tunnels. If analysts find the rock is too unstable to handle drilling, or that water levels would complicate keeping the road dry, the tunnel is toast.
H. Tony Rahimian, a consultant managing the project for the two counties, said the best case scenario for building the tunnel would be dense rock suitable for boring by a machine, and low water levels.
"We want to make sure we can seal the tunnel effectively," Rahimian said. "So a lot of water is a problem."
Holes are planned for five sites, allowing officials to test rock density and water levels along the proposed route. Rahimian said transportation officials are eager to partner with the Metropolitan Water District, which plans its own mountain tunnel to deliver water to south Orange County.
Teams boring the four-inch holes more than 2,000 feet are flown to the site daily, Rahimian said. Equipment is kept in the forest, but guarded, he added. Drilling last year by the water district was delayed after equipment was damaged, presumably by vandals, Rahimian said.
He stressed the U.S. Forest Service vetted the drilling plans, and agreed they would not harm the forest.
Talk of the tunnel began in earnest in 2005, after Orange and Riverside county officials chose it and two road widening projects as their preferred ways of easing traffic congestion. The tunnel was the most controversial and expensive of the three options, because of cost and opposition from Orange County residents.
The Riverside commission partnered with the Orange County Transportation Authority and Foothill Eastern Transportation Corridor Agency to form the Riverside Orange Corridor Authority that oversees the project. RCTC Project Development Director Cathy Bechtel said the tunnel is only part of the region's traffic solution. Transportation officials must give commuters alternatives to Highway 91.
"Based on the future traffic needs, if we only did (Hwy.) 91, we'd have to blow it out to 22 lanes," Bechtel said.
Plans to build a freeway parallel to Hwy. 91, or possibly above it, and widening Highway 74 are part of a study Riverside and Orange county officials approved in December 2006.
Bechtel stressed the tunnel plan, estimated in 2005 to cost $6 billion, is in the very early stages. It could be more than 10 years before drivers go underground.
Reach Dug Begley at 951-368-9475 or dbegley@...