Progress of the Blacksnake Tunneling Project
Super Excavators, the contractor hired by the City of St. Joseph to construct the Blacksnake Creek Stormwater Separation tunnel from near the Second Harvest Food Bank to Roy’s Branch, will complete the boring operation by the end of November.
Recapping earlier activities:
- The contractor constructed a secant wall for the launch shaft west of MacArthur Drive, preparing for the delivery of the tunnel boring machine. Work then began on the jack and bore portion of the project that drove new pipe under the Burlington Northern – Santa Fe tracks to Roy’s Branch.
- The tunnel boring machine (TBM), specifically an earth pressure balance boring machine (ETBM), was constructed by Lovesuns and delivered to St. Joseph in early April 2018. It is a single pass machine, meaning the equipment bores through the subsurface material, pulling pipe in-place behind it.
- The TBM will be extracted near the Food Bank at the east end of the tunnel, a location which will house the tunnel drop shaft when in operation later in 2019. The completed tunnel has an outside diameter of 123 inches and an inside diameter of 108 inches.
- Work on Roy’s Branch, located south of the Remington Nature Center, began earlier in 2018 with MEGA construction acting as the contractor. Stormwater conveyed by the new tunnel will discharge into Roy’s Branch and then flow into the Missouri River. That work was significantly delayed because of a flooding Missouri River operating at flood stage since early March. Work to Roy’s Branch will include bank stabilization and work to widen and deepen the stream. The construction of a new bridge to accommodate traffic on the Riverfront Trail has already been completed. Plantings and erosion protection will be added to the project to restore it to a more attractive and functional ecosystem, although this has also been delayed by conditions on the Missouri River.
- The majority of the tree re-planting is near completion by Pine Valley Contracting. Approximately 900 trees were re-planted to mitigate the tree removals necessary to construct the project.
Once the boring machine is removed from the tunnel, the drop-shaft will be completed at the retrieval site. At the launch site near the river, an energy dissipation structure will be completed. Flow from the energy dissipation structure will flow through pipes under the railroad tracks and into Roy’s Branch.
The Blacksnake Creek tunnel will divert approximately two million gallons of clean creek water per day during dry weather, and up to a three-month storm during rain events, or 800 million gallons per event (approximately 20% of the overall program goal in one project). The entire Combined Sewer Overflow Program’s goal is to treat or divert four billion gallons per year in total, which is volumetrically 85% of the stormwater generated in St. Joseph in an average year.
