The big excavation project under way atop Cory Bluff to reestablish irrigation water flows for the North Delta Irrigation Company will continue.
After workers finally installed a four-foot diameter pipeline through the partially collapsed, quarter-mile-long tunnel on May 25, another problem now has to be dealt with.
Water flow though the pipeline is being restricted.
Company representative Lynn French told the Delta County Independent on Monday the cause is thought to be that the pipeline is not on a proper grade. It is thought to be lying either atop debris within the tunnel, debris left by last summer's partial collapse and recent construction work; or the pipeline may be atop a geologic structure, "a rise," within the tunnel.
The first scenario would be relatively simpler to deal with, French said. The second would require lots more digging, including use of a small excavator working within the excavation and alongside the pipeline some 90 feet or more below ground level to remove material from the tunnel floor and establish the right grade for water to flow.
The tunnel was constructed 110 years ago with very little elevation difference between the east and west portals, explained French. He said the pipeline is flowing about one-third as much water as it should be.
The additional work has required that Iris Road be closed at the west side of Cory Bluff. The excavating contractor is using a previously mined area north of the road to store the additional earth that is being taken out.blog comments powered by Disqus