Brian Shippy and Todd Merchen (left) show Councilmen Dan Barks, Robin Kuntz and Shay Lundvall corroded rebar
(Gillette, Wyo.) The city council work session took place on the streets last night as Mayor Louise Carter-King, accompanied by the city council members and city staff, set out to see several ongoing and future projects first-hand.
There were four projects that the council toured, including potential locations for new facilities at Dalbey Memorial Park near the little league fields and at the Energy Capital Sports Complex.
The council was scheduled to tour locations for the installation of the THOR Lightning Detection Systems—technology that would keep residents informed of the potential for lightning strikes within a certain radius.
After a quick briefing on the lightning detection system, the council approved the steps necessary to begin installing the technology which should be complete before the end of next summer, according to City Administrator Patrick Davidson.
The council spent the most time touring the progress being made on the Gurley Overpass as they were led into the construction zone by Todd Merchen, city project supervisor for the overpass, and Brian Shippy with Structural Dynamics.
Right off the bat, the council noted a pile of soon to be installed green, epoxy-coated rebar, technology that was available at the time the overpass was originally constructed, though it was considerably more expensive than the plain metal rebar that had been used.
The benefits of the epoxy-coated rebar are immense.
“If you’d had epoxy-coated rebar on this bridge 40-years-ago, you probably wouldn’t have touched it to this point,” Shippy informed the council. “That’s the problem with bare steel, it just corrodes so quickly.”
From the underside of the overpass, rust from the old rebar and spots of Ice Slicer, the road deicer that is currently being used by the city, could easily be seen seeping through. From the top, the council could see the meters of corroded rebar that they had been informed of several weeks ago.
Here and there, X’s marked spots of what Shippy and Merchen referred to as “sound concrete,” which made a noticeable, solid sound when a chain was dragged across it. The chain was attached to a meter-long pole that is held similarly to a broom handle. It is used to detect sections of “unsound concrete”—sections of concrete that have become delaminated from the surrounding layers of concrete—that echoes with a dull, hollow sound when the chain runs over it in a sweeping motion. The process of chaining the deck is slow and arduous.
“It’s like sweeping a 30,000 square-foot floor four or five times by the time you’re done with these projects” Shippy said.
The bridge continues to deteriorate, hence the need for a whole new deck. In 10 years’ time, however, a complete re-build will be needed as the bridge nears the end of its lifespan.
Councilman Robin Kuntz took a moment to state that, when the bridge reaches the point that a rebuild is necessary, there will be no need to move it somewhere else.
“We’ve got everything we need,” Kuntz said.
There is plenty of land to accommodate a wider bridge, if that is direction the city wishes to go, which means the city would not have to purchase more land in order to do so. The absence of land costs would make the rebuild project considerably less than if the overpass was re-built somewhere else.
Cost would be further reduced if the city chooses to “roll-over” any unused funds once the re-decking project is complete, much like they did with the $300,000 saved during the barrier rehabilitation project last year.
Shippy recommended that the city consider some sort of annual maintenance that would last around a week to preserve the overpasses longevity, during which the overpass would be closed, for the duration of a week, but no official decision was made last night.