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CDOT to repair Jackson Mountain landslide

Orange cones and heavy equipment will grace U.S. 160 seven miles east of Pagosa beginning this fall as the Colorado Department of Transportation (CDOT) launches a significant improvement project on the Jackson Mountain landslide — to the tune of $6.1 million.

According to CDOT, the stretch of roadway traversing the landslide requires patching every few months to maintain road elevation and alignment, at a cost of $100,000-$250,000 yearly, equating to millions of dollars over the years.

The project is slated to begin construction in August or September, with completion projected for the summer of 2011.

The proposed work to the section includes regrading the slope on the north side of U.S. 160; installing horizontal, underground drains to lower groundwater levels; reinforcing the roadway with a geo-grid subgrade; and installing riprap (rock) buttresses at the base of the slope where it meets the San Juan River.

The design work for the project is 80-90 percent complete, noted CDOT Resident Engineer Ed Archuleta.

The first order of business this fall will be to attempt to drain groundwater and divert the surface water then, during next summer’s lowflow season, the riprap buttresses will be built and the rest of the project will be completed, Archuleta said.

The project will be no easy feat for construction crews, with the bedrock covered by 50-80 feet of shale. Crews will also have to remove over 10 feet of asphalt, which has built up from the constant repair work, while building the approximately 1,000 feet of reinforced roadway one lane at a time in order to keep the road open, Archuleta said.

Currently, the river cuts the toe of the slope, while sloping bedrock and high groundwater levels further decrease its stability. The result is a landslide which, according to CDOT, dropped as much as eight vertical inches in one night, in the spring of 2005.

Money for the reconstruction project will come from CDOT’s contingency fund, which is the entity’s emergency reserve. The decision to use the $6.1 million from those funds was made at a Dec. 17 meeting of the Transportation Commission.

While the Jackson Mountain slide has been on CDOT’s radar for decades, the recent increase in its deterioration and another, worse slide on U.S. 50 were enough to convince CDOT to release contingency funds for the two projects.

“In my opinion, this is becoming an emergency situation,” said Transportation Commissioner Steve Parker. “U.S. 160 is our lifeline to the rest of the state.”

Archuleta County Commissioner Bob Moomaw, the commissioner designated to represent the county at Southwest Colorado Transportation Regional Plan meetings, worked with Parker to move the slide up on the priority list.

“The point I kept hammering home was, with Jackson Mountain, if it failed, it would have catastrophic consequences,” said Moomaw.

Parker viewed the situation similarly, noting that if the road failed and transportation of groceries and other goods to this side of the pass were stopped, “that’s wasting the millions of dollars” poured into the Wolf Creek Pass improvements. “It’s our interstate; that’s the way I see it.”

randi@pagosasun.com