The existing water reticulation network in Makhanda, (formerly Grahamstown), is subject to frequent breakages due to its age and transient pressures, leading to water outages and water losses. The replacement of the ageing asbestos pipes will assist significantly in alleviating water losses, high operation and maintenance costs and the distress experienced by the public and businesses in the Makana Local Municipality.
MBB Consulting Engineers was appointed by the Makana Municipality for the design, tender documentation, and construction monitoring of the replacement of ageing asbestos pipes in Makhanda (Phase 3). The original scope of the project was to replace approximately 10,6 kilometres of aged asbestos pipes with unplasticized Polyvinyl Chloride (uPVC) and High-density polyethylene (HDPE) pipes. New valves, valve chambers and fire hydrants were also to be provided. On completion, the new pipes would be tied into the existing pipework and the house connections and meters migrated to the new water lines. The decommissioned asbestos lines will be left in place.
The scope of the project has been separated into two phases i.e., Phase 3A being 6,8 km long and Phase 3B being 3,8 km long, further subdivided into zones i.e. Zone A, B and C which also included approximately 100m of river or stream crossings that were to be replaced with galvanized steel pipes. The work split was such that two contractors were to be appointed, allowing for speedy implementation, as the municipality wanted early completion of the project. Ultimately the same contractor was appointed for both contracts.
Upon investigating and locating the existing underground infrastructure it was determined that most of the works would have to be undertaken within the roadways, as the road verges did not have sufficient workspace due to trees, fibre cables, existing waterlines, and existing sewer lines. Hence the installation of the new water pipes has been carried out on the pavement with the trench depths ranging from 1,25m to 1,4m.
Working on the pavement is more costly when compared to working on verges, this necessitated reducing the pipe lengths to be replaced to stay within the budget. Phase 3A’s original length of pipe to be replaced was reduced from 6,8km to 5,3km. The majority of the pipe work has been installed concurrently with the installation of valves, valve chambers and fire hydrants. The contractor is yet to carry out several outstanding activities i.e. pressure testing, reinstatement of asphalt, house connections and tie-in to the existing network. Phase 3B has reached practical completion with almost all the work complete i.e. installation of the pipes, pressure testing, house connections, fire hydrant connection and reinstatement of asphalt reinstatement. The contractor is attending to the remaining snags.
The project is expected to be complete by the end of February 2024.
Below is a selection of the construction photographs.
Phase 3A Project
Phases 3A & 3B Project Construction photographs