Lynchburg Water Resources (LWR), the municipal utility in Lynchburg, Virginia, is set to begin the drill-and-blast phase of the Blackwater Combined Sewer Overflow (CSO) Tunnel project in Virginia, US.
The Blackwater CSO Tunnel Project, also known as LYHBeyond, is the largest capital improvement project in Lynchburg and protects the city’s waterways, said the municipal utility.
It includes the construction of a nearly mile-long, mile-long, 12ft diameter underground tunnel that can store up to 4.7 million gallons of combined sewage and stormwater.
LWR’s contractor Atkinson Construction will begin construction at the main project site located at the bottom of Seventh Street in Downtown Lynchburg.
The Blackwater CSO Tunnel, measuring 70 to 120ft, will be constructed through a solid rock beneath Blackwater Creek using drill-and-blast excavation methods.
The process includes drilling multiple holes into the rock, placing blasting material in the drilled holes, detonating the material, and removing the rock.
Detonation of each blast hole will be preceded by a series of air horn blares to ensure safety.
The first test blast is scheduled for 13 January 2025, using 25% of the typical blasting material, and is subject to potential delays.
The test blast and all future blasts will follow a safety protocol with five short air horn blares five minutes before detonation and another series one minute prior.
A long air horn blare will signal all clear after each blast, followed by another long blare to signal to crews that the tunnel shaft is safe to enter.
Drilling and blasting will occur within a 38ft wide shaft already constructed at the Seventh Street site, which will be covered to mitigate noise and contain the blasted rock.
The amount of blasting material will increase with subsequent blasts, from one to two blasts per week for the next two months, to two per day starting this spring.
The drill-and-blast phase of the tunnel project is planned to continue until July 2026.
