A one-mile segment of the Olmstead Aqueduct in Provo Canyon that rests on the surface of an active landslide will be replaced by a tunnel expected to cost about $8 million.
The Central Utah Water Conservancy Board decided Thursday to go ahead with the tunneling plans after several years of study and test drilling in the mountain behind the slide.The conservancy district is now pursuing a contract for engineering the 5,000-foot-long tunnel that will go around the slide area.
The 102-inch diameter pipeline previously owned and operated by Utah Power & Light, was taken over recently by the U.S. Bureau of Reclamation for use by the Central Utah Project, controlled locally by the conservancy district.
A UP&L spokesman has said the troubled stretch of the pipeline has kinked and broken a number of times as the landslide, between Canyon Glenn and Nunns Crossing, slowly carried it down the hill in wet years. UP&L chose to occasionally hike the pipeline back into place with bulldozers rather than pursue a costly realignment or tunneling.
But water officials said the bulldozer fix is not acceptable now that the pipeline will be used to carry culinary supplies.
The conservancy district has also considered burying the sliding portion of the pipeline in a deep trench and letting the slide cross over it. The Bureau of Reclamation also considered building a massive siphon that would have routed the pipeline down the side of the canyon, around the slide and back up to meet a stable section of the pipeline downstream.
The bureau has not been included in the conservancy district's current plan to engineer or cut the tunnel.