Heritage Cases

The sheet piles have corroded significantly with large holes visible in the tidal zone. These holes have caused leaching of backfill material resulting in the subsidence of the back of quay area. Transnet National Port Authority (TNPA) has undertaken numerous repair campaigns involving filling holes with soilcrete. However, the continued deterioration of the sheet pile wall has resulted in an unsustainable maintenance regime. This led to the establishment of this project, which is to develop a long-term repair solution to make the quay safe to use and require minimum maintenance Alternatives PRDW were appointed by Transnet to conduct a pre-feasibility (FEL 2) study for the rehabilitation of the Old Tug Jetty sheet pile wall. A set of rehabilitation concepts for the Old Tug Jetty sheet pile wall were developed based on typical marine structure types, construction techniques, functional requirements, and existing site conditions. A prescreening assessment of the concepts was then undertaken using a high level, qualitative, multi-criteria analysis to eliminate options that were not considered viable, or which had fatal flaws. Thereafter, the remaining options were assessed in a multi-criteria analysis to determine the preferred solution. The full set of Old Tug Jetty sheet pile wall rehabilitation options that were considered for the pre-screening assessment are detailed in the EIA Report. All the rehabilitation options presented assume that the existing Old Tug Jetty sheet pile wall will be abandoned and buried and the back of quay area remediated. This means that the counterfort units will be placed proud of the existing sheet pile wall. There will be infilling of rock material between the old sheet pile wall and the new counterfort units with the construction of a new elevated cope, totally encasing the existing sheet pile wall, hence the term “buried and abandoned” (Figure 5). Although the old sheet pile wall will remain, it will no longer be in use and will be encased by the new structure, covered by the counterfort wall and will not be visible due to backfilling and concrete capping. Please refer to the full optioneering and multicriteria analysis report which has been attached as Appendix C.