Waterfront Tunnel - Alexandria Virginia

GEO's Alexandria Team

The Herrenknecht TBM used by AlexRenew, Alexandria Virginia's water treatment service. The TBM was named for Hazel Johnson, one of America’s leading pioneers for environmental justice.

TBM will be lowered into shaft to begin its 2 mile run

Hazel next to the launch shaft. After launching, Hazel proceeded to excavate the 2-mile long Waterfront Tunnel at an average depth of 100 feet. The tunnel captures and transports combined sewage to the AlexRenew facility where it is purified and returned to the Potomac River.

Waterfront Tunnel Alignment

AlexRenew has provided pre-construction surveys to owners and residents as part of its community outreach. GEO monitored for potential movement of road surfaces, underground utilities, and structures along the path of the tunnel boring machine. Map and conceptional drawing of instrumentation courtesy of AlexRenew.

Instrumentation Concept for AlexRenew

GEO installed 10 AMTS systems for measuring structural monitoring points ( 136 L-Bar Prisms) and ground monitoring points (87 Road Prisms). Other instrumentation included 12 RVM vibration monitors, 46 borehole extensometers, tiltmeters, utility monitoring points, piezometers, and strain gauges (for shaft SOE).