Fish Water Flats

The Fish Water Flats Waste Water Treatment Works was constructed in 1976. The final phase for the Fish Water Flats Waste Water Treatment Works (FWF WWTW) formed part of the maintenance backlog of all buildings and structures previously logged into the Nelson Mandela Bay Municipality database as part of the Maintenance Backlog Study for Fish Water Flats Waste Water Treatment Works.

Africoast Consulting Engineers was brought in to this project to foresee activities such as the planning, design, tender and supervision. During the planning and design stage careful consideration was given to the type of repair and protective coatings to be used.

The objective of the rehabilitation method was to fulfil the requirements of minimum strength, serviceability, ease of construction and cost. The requirements of minimum strength and serviceability were to ensure adequate safety and performance of the structure subject to loads and environmental conditions. The protection of embedded steel from corrosion was deemed essential for adequate serviceability. The rehabilitation method adopted was in accordance with accepted Codes of Practice for the rehabilitation of concrete structures.

The buildings and structures are situated in a severe marine environment and are exposed to corrosive salt spray from the on-shore prevailing easterly winds. The buildings and structures at the Fish Water Flats Waste Water Treatment Works (FWFWWTW) experienced varying degree of inadequate maintenance and corrosion related deterioration.

There was visible degradation and concrete spalling of the concrete structures which led to the following primary concerns:

  • Long term durability of the structures being at risk.
  • Visible degradation of the structures.
  • Hidden corrosion to the reinforcing steel that is not externally visible.
  • Increased long-term maintenance costs due to uneconomical maintenance strategies.


This project dealt only with the building maintenance and structural rehabilitation to the Fish Water Flats Waste Water Treatment Works Phase 4