Construction is underway across all 16 km/10 miles of the HRBT Expansion Project. Over the past four weeks there has been recognizable progress on the South Island for the HRBT Expansion Project .
Hampton Roads Connector Partners (HRCP) construction crews have been busy advancing work in the tri-cell launch shaft on the South Island. The crews are preparing it for use in assembling -- and later launching -- the TBM.
Following completion of the excavation stage of the shaft in mid-July, HRCP placed 2727 m3/3580 cubic yards, or 6577 t/14.5 million pounds of concrete over a 24-hour period to form the 2.13 m/7-foot-thick base slab of Cell 3. HRCP crews used an innovative method involving liquid nitrogen to keep the concrete cooled to the appropriate temperature as it was placed and then subsequently cured.
The base slab will be ready to support the assembly of the TBM gantries, or trailing gear, that form the majority of Mary’s 134 m/440-foot length.
Since TBM Mary’s arrival on to the South Island, reassembling has begun: click here for a video. It will take the HRBT Expansion Project crew between four to six months to put her back together. A welding tent provides a barrier around the clock, against severe weather conditions such as wind, rain and direct sunlight.
Before TBM Mary can start building the new twin tunnels, the crew had to construct and then lower the sealing ring (“shuttering pipe”) into the South Island launch pit headwall. These 14 m/46-foot-diameter steel rings are needed to put the TBM under pressure when it first starts boring!
Then just at the end of last month, another enormous concrete slab took shape for the Slurry Treatment Plant (STP) slab on the South Island. Over the course of four months, crews have been laying tons of rebar for this slab that will serve as part of the foundation for Katherine, the STP. This plant, which will be assembled this fall, will receive the excavated materials from Mary and separate the sediment from the water so the materials can be disposed of properly.
Click here for more details on the HRBT expansion project updates, here and us/125 for the tunnelbuilder archive reports. Also visit www.hrbtexpansion.org. 32/22
