ABSTRACT
This paper presents an assessment of the options available for the new water abstraction works for Mthatha Dam, South Africa. The current abstraction works, which are in a critical state of repair, are the only source of water conveyance to the Water Treatment Works of Mthatha Town. Due to critical timeframes, a rapid and cost effective construction method is required to safeguard the water supply. The proposed abstraction works consist of a low lift pump station and two 150 m long tunnels which will be constructed under high water pressure and tunnelled into the water body. The options assessment compares a drill and blast lake tap methodology to the relatively new method, in a Sub-Saharan African context, of microbore tunnelling with an in-lake retrieval.
