Shoreline Storage Tunnel Shafts and Near Surface Structures Support of Excavation-PPT Presentation

PPT Presentation

Pdf Summary

The Shoreline Storage Tunnel (SST) is the fifth of seven major tunnels in the Northeast Ohio Regional Sewer District’s Project Clean Lake, a 25-year program to reduce combined sewer overflow discharges into Lake Erie by 4 billion gallons annually. Located in Cleveland, the SST is 14,100 feet long with a 23-foot inside diameter.

The presentation describes excavation support for three large slurry-wall shafts, tunnel boring machine (TBM) break-in or break-out blocks, and near-surface support-of-excavation structures. Slurry walls provide excavation support and groundwater cutoff. Construction typically involves guidewalls, panel excavation under bentonite-cement slurry, reinforcement where required, and tremie-concrete placement. Cement-bentonite panels are also used to improve ground strength, control water, or provide excavation support.

The three shafts were:
- <strong>SST-1:</strong> 66.5-foot inside diameter and 129 feet deep, formed from 10 triple-bite panels. It was unreinforced and extended into rock at its base. Its break-in block used 15 cement-bentonite panels, 117 feet deep, installed before the shaft walls.
- <strong>SST-2:</strong> 55.5-foot diameter and 160 feet deep, formed from nine triple-bite panels. It was unreinforced, with in-situ clay serving as the bottom plug. A nearby near-surface structure used 40 single-bite panels, 73 feet deep.
- <strong>SST-3:</strong> 45-foot diameter and 133 feet deep, formed from seven triple-bite panels. It was unreinforced, with in-situ clay as the bottom plug. Its TBM and micro-TBM break-out blocks used 24 and six cement-bentonite panels, respectively. Two near-surface structures were also built.

Together, these techniques provided deep shaft support, groundwater control, and excavation support for the tunnel’s associated structures.

Keywords

Shoreline Storage Tunnel

Project Clean Lake

combined sewer overflow

slurry-wall shafts

TBM break-in

TBM break-out

cement-bentonite panels

groundwater cutoff

excavation support

Northeast Ohio Regional Sewer District