Design Considerations and Construction Strategies for the uMkhomazi Water Project Phase 1
Authors: M. Nasiri1, G.J. Keyter1, U. Rehm2, T. Mac Kellar2
Conference: SANCOT Symposium 2026
Date: April 13-14, 2026
1 SRK Consulting, South Africa
2 Knight Piésold, South Africa
ABSTRACT
The uMkhomazi Water Project Phase 1 (uMWP-1) aims to augment water supply to the uMngeni Water Supply System (MWSS) in KwaZulu-Natal to address long-term regional water demand. A key component of the scheme is a 34 km waterway tunnel driven primarily by tunnel boring machines (TBMs), connecting the uMkhomazi intake to the Baynesfield outlet. The project presents several design and construction challenges, particularly due to the constraints of working within a relatively small 3.5 m internal diameter tunnel.
This paper outlines the main engineering strategies developed to manage these challenges, with preliminary design work completed to date, focused on practical solutions for tunnel logistics, including muck removal, segment transport, sequencing of construction activities, and the efficient use of equipment within the limited tunnel space. These aspects are essential in deriving workable construeition methods for these long, small-diameter TBM tunnels. The paper also summarises options for TBM removal at the Baynesfield outlet, which represents a major project milestone with implications for programme, cost, and interfaces with downstream infrastructure.
Overall, the study highlights the importance of coordinated planning, effective logistics, and careful sequencing during the preliminruy design phase to better manage construction risks and ensure long-term operability in complex tunnelling projects.
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