County hears warning about 9-Mile road earthwork
Could the $20 million Nine Mile Canyon road project be undermined by roots and twigs?
Yes, said Dave Smith, a former road construction worker who is now an environmental consultant and county commission candidate.
No, countered engineers with Jones & DeMille Engineering and a vice president for the general contractor W. W. Clyde Co.
Both sides appeared at a special county commission meeting Tuesday, called to examine the concerns that Smith had raised. The gist of Smith's observations of the project is that too much organic matter - plant pieces knocked loose in clearing the land for roadwork - is being buried in the road base.
This "organic" soil poses problems for the future. It rots or shrinks over time, opening subsurface pathways for water to permeate and saturate the ground. It also does not compact well. In time, parts of the road are "guaranteed to collapse," Smith told commissioners.
Brian Barton of the engineering firm replied that the problems organic materials create are understood, and this is why the procedure is to collect, remove and burn all the native plants after clearing and grubbing the road side.
County Engineer Curtis Page agreed with Barton, explaining to commissioners that inspectors get to see cross sections of the road every few hundred feet. This happens because trenches are excavated at regular intervals to carry drainage pipes across the road. If there was organic matter in any quantity to cause concern, it would be visible, Page said.
But Smith contended the practice of using toothed buckets on trackhoes for clearing plants allows a lot of matter to escape. He recommended using solid blades to cut through the top six inches of soil and haul it all away.
Garrett McMullen, another engineer with Jones & DeMille, replied there are budget constraints to consider in cutting down to any depth. The construction team has been working with a $20 million budget to build 36 miles of road. That means that native soils in the canyon have to be used. To remove and replace with imported granular material might push the cost up to $80 million.
County Commissioner Mike Milovich quipped, "We didn't have the budget to do an I-15 corridor." But Milovich did recommend that the county do its own testing along points of the road, a proposal that was accepted.
Commissioner Jae Potter asked the engineers and construction contractor if the road is being built to UDOT standards, leaving an option open for some future takeover of the road by the state.
The answer was yes.
Mike Bigsby, a vice president for W.W. Clyde, said his company has been following sound construction practices and is working daily with the engineers to make sure all specifications are being met.