Box Culvert Bridge Replacement

The Sisseton-Wahpeton Oyate (SWO) and Bureau of Indian Affairs (BIA) had determined that the existing wood bridge structure along BIA Route 121 was deficient. The bridge spanned over Big Spring Creek on the Lake Traverse Reservation in northeast South Dakota and was the only access to a dozen residences. DGR Engineering (DGR) worked with the SWO and BIA staff to design an economically feasible replacement for the failing structure.

Initial planning phases included a Type, Size & Location (TS&L) report to provide options that would meet the client’s needs. DGR teamed with Erickson Engineering to provide four alternatives, including associated costs, hydraulic analysis and project timelines. After meeting with the SWO and BIA to review the options, it was decided that a 20’x8’ pre-cast single-cell box culvert would be the best solution to replace the existing bridge.

The decision to install a single-cell box culvert of this size was made due to the upstream drainage basin being heavily wooded. There was concern that branches and debris could potentially block a double-cell structure. Since the existing road was the only access to several residential properties, a temporary detour route was necessary during construction to maintain access throughout the project.

DGR coordinated the purchase of the additional right-of-way needed for the project and obtained the required environmental clearances. Once the plans were approved and the construction budget was set, the SWO let the project out for bids and DGR provided full-time construction administration services. Construction began in September of 2018 and was completed in November 2018.

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