DEADWOOD — The Lawrence County Commission heard project updates from Highway Superintendent Allan Bonnema on three bridges slated for rehab or replacement over the summer, with some projects already in full swing or just ready to ramp up.
Exit 10 bridge rehab
Bridge work on a structure that spans Spearfish Creek and is located on old Highway 14 near the KOA Campground at Exit 10 is nearing completion.
Bonnema said the reason for the rehab is that the concrete on the bridge is rotten.
The bridge rehab, bid during the summer of 2019 for $427,000, entails a new bridge deck, bridge railing, and guard rail.
Tthe project is being performed in concert with the state of South Dakota and its Bridge Improvement Grant (BIG) program at a 50/50 cost share.
The county will be responsible for around $204,000 in costs, while the BIG program will pay around $223,067.
Bonnema said previously the substructure underneath the bridge is still in good shape.
“The steel girders are in good shape, the concrete deck itself is not so good,” Bonnema said.
Approximately two years ago, it was discovered that the west end of the bridge, approximately 30- to 40-feet of the bridge deck, is hollowed out; the rotting, due in part, to salt erosion.
“It’s honeycombed and it’s rotten,” Bonnema said. “It gets holes in the deck all the time. Structurally the bridge is sound, it’s just that the concrete is old and is failing, so it’s due for a rehabilitation.”w
The engineer’s estimate on the project was $424,000.
Bonnema said the project is coming along nicely but won’t be finished by the original finish date of May 22.
“Bid date for completion is July 1,” Bonnema said.
Whitewood Valley Bridge
The bid on the Whitewood Valley Road bridge was awarded in December 2019 in the amount of $1,663,047.
A BIG grant was approved on the structure in April 2019 for $664,100, leaving the county’s share of repairing the bridge at $998,947.
The engineer’s estimate on the project was $1.7 million.
The construction deadline on the Whitewood Valley bridge is Oct. 31.
Dorsett Road Bridge
“That contractor is still saying he won’t be getting started on that project until sometime in July,” Bonnema said, adding the project won’t be completed until fall. “They have to be done by Oct. 31.”
The state awarded the bid on the Dorsett Road Bridge earlier this year in the amount of $619,963.55.
A 20% cost-share with the state on the project, or $123,992.71, will be split between Lawrence and Butte counties.
“Our cost is $61,996.35,” Bonnema said.
The Dorsett Road bridge is located northwest of Spearfish.
The old bridge is shut to traffic because it was starting to fall down.
The engineer’s estimate on the project was $602,583.
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