Engineers and experts from the Lesotho Highlands Development Authority (LHDA) have inspected the Tunnel Boring Machines (TBMs) that are set to excavate the 38km Polihali Transfer Tunnel, part of Phase II of the Lesotho Highlands Water Project.
The factory acceptance test took place from May 8 to 11, 2024, at the CCCC Tianhe plant in Changshu City, Jiangsu Province, China. Participants included LHDA senior engineers, representatives from Metsi a Senqu Khubelu Consultants (MSKC), the Kopano Ke Matla Joint Venture, and TBM designer Robbins.
The inspection aimed to verify that the TBMs meet design and safety specifications
“We verified the design of the TBMs, their functionality and adherence to safety standards,” said Neo Thinyane, Phase II Senior Projects Engineer. “This included examining the cutterheads, backup systems and segment erection mechanisms.”
The team also evaluated muck removal, power supply, ventilation, water supply, and dewatering systems.
Safety features were a key focus, including walkways, head clearance, gas detection systems, and fire suppression systems. The TBMs are equipped with refuge bays containing life-support systems and backup power and cooling systems.
Designed to handle challenging basalt rock formations, the TBMs will facilitate water transfer from the Polihali reservoir to the Katse reservoir using both boring and drill-and-blast methods. The tunnel works include intake and outlet works, gate shafts, and access adits.
Significant progress has been made on these components. The TBMs, with a 5.39m diameter and 415m backup systems, are expected to arrive in Lesotho later this year.
MSKC designed the tunnel and provided the TBM specifications, while Robbins, a U.S. company, designed the machines. Kopano Ke Matla Joint Venture is constructing the tunnel.
