DEADWOOD — Retaining walls in Whitewood Creek didn’t fare too well when a July 4 hail and rainstorm roared through town, leaving a path of destruction its wake. Tuesday, Deadwood City Commissioners granted permission to enter into contract with Albertson Engineering to address mitigating the damage in the amount of $18,670.
“Being brought forth by Albertson Engineering is primarily structural, but will also be civil engineering, due to the fact that we’re in a floodway floodplain and there will be geotechnical,” said Public Works Director Bob Nelson, Jr. “We have to do soil borings behind retaining walls and may actually have to do some in the stream itself to find out where we can rebuild some of these walls. This will get us zeroed in on the proper fixes with some accurate cost estimates, give us some cross-sections of different types of walls, what the best remedy is.”
Focus area one is from Deadwood Mountain Grand to the Walnut Street bridge.
Focus area two is Super 8 Motel to Deadwood Gulch Hotel.
The engineering assessment will include Drill (1) Standard Penetration Test (SPT) boring on the high side of the east bank behind Comfort Inn, as well as Drill (1) SPT boring in the parking lot near the failed creek bank across from Powerhouse Park. This boring will assist in determining bank stability repair options and associated costs.
The assessment will also include an opinion of current conditions of both sites, specifically slope stability and floodplain/floodway concerns, storm sewer outlets on the high side of the south bank, and erosion of soft soils below the bedrock at the Comfort Inn site.
Varying degrees of gabion wall failure, slope stability issues by Powerhouse Park affecting parking lot safety, floodplain/floodway concerns, erosion below existing retaining walls, including along Deadwood Mountain Grand will be addressed in the assessment, as well.
Conceptual options for recommended repairs and a preliminary opinion of probable cost will then be provided to the city by Albertson Engineering, the report to be delivered to the city by Sept. 27.
Commissioner Sharon Martinisko pointed out that boring will be conducted behind Comfort Inn.
“I’m assuming you go inland from that or are they going to have to take out some concrete?”
Nelson said he did not know at this point.
“In the event that FEMA does come through with some funds, this is reimbursable,” Nelson said.
The engineering services will be paid from excess hail insurance proceeds, line itemed in public buildings.
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