The Blackwater Combined Sewer Overflow (CSO) Tunnel is a major wastewater infrastructure project designed to significantly reduce combined sewer overflows into local waterways. The approximately 4,744-foot underground tunnel extends through bedrock and will provide up to 4.7 million gallons of temporary storage for combined stormwater and wastewater during heavy rainfall events.
Stiver Engineering provided specialized underground and structural engineering services supporting construction of the tunnel and pump station facilities. Our work included shaft initial ground support, tunnel ground support, and structural design of a temporary shaft blast cover.
Shaft Initial Ground Support
Stiver Engineering designed initial ground support for the pump station shaft within the rock zone. Our team evaluated available geotechnical information and anticipated rock conditions to develop support recommendations appropriate for shaft excavation and construction.
Tunnel Ground Support
Stiver Engineering evaluated varying ground conditions along the tunnel alignment and developed multiple ground support configurations. The recommendations provided flexibility to accommodate changing rock conditions encountered during excavation while supporting stability of the underground opening.
Shaft Blast Cover Design
Stiver Engineering designed a temporary blast cover for the pump station shaft to support construction operations. The multi-panel steel-framed system was evaluated for applicable loading, stability, structural adequacy, and handling requirements.
Through these services, Stiver Engineering provided coordinated underground and structural solutions supporting construction of this significant wastewater storage and conveyance project.
