Von Bach Dam Asphalt Rehabilitation Project

Project Overview

The Von Bach Dam is located outside Okahandja in the Otjozondjupa Region in central Namibia. Knight Piésold was appointed to investigate the condition of Von Bach Dam’s asphalt seal and determine whether it required refurbishment or could continue operating as a watertight membrane. The outcome of the investigation, based on core drilling results, indicated that cracks in the asphalt had penetrated to a significant depth and, together with the deteriorated condition of the bitumen, the membrane required immediate replacement.

Project Role

The project involved construction supervision of the site preparation, milling-off of the old asphalt, joint preparation, installation of the new asphaltic binder layer (ABL), and installation of a new dense asphaltic concrete layer. Services included:

• Detailed investigation of the asphalt lining of the 35-m-high CFRD dam, which included core drilling and analyses of the asphalt material
• Hydrology studies
• Preliminary and detailed designs
• Contractual and administrative management to assist the client in appointing the contractor and managing the contract
• Construction supervision for the milling-off of the old asphalt, installation of the new ABL, and the joint construction
• Recommendations for and management of a fast track process to obtain quotes from selected asphaltic dam specialists and evaluation and presentation of the best offer to the client
• Installation of a check point for the copper plate joint and survey of the position of the ABL drainage points before covering
• Update of the as-built drawings with the new information
• Administrative assistance to the contractor to obtain work visas, expedite import clearance, and enable rapid site establishment
• Construction supervision of the post-construction joint treatment and the placing of a new mastic seal

Within two months from mobilizing the contractor’s equipment from Europe, the contractor completed the project according to programme. Two months later, after receiving summer inflow, the dam was 50% full, inundating a portion of the new watertight asphalt lining.

Award

Commendation, Best International Project Category, Von Bach Dam Asphaltic Seal Replacement Project, Consulting Engineers South Africa, 2018 Aon Engineering Excellence Awards