Name of the Project
Clanwilliam dam and irrigation scheme upgrade project.

Location
On the Olifants river, in the Western Cape, South Africa.

Project Owner/s
The stakeholders include the Department of Water and Sanitation (DWS), the Lower Olifants River Water User Association; the Cederberg, Matzikama and West Coast municipalities; the Western Cape provincial government; the South African National Roads Agency Limited (Sanral); and power utility Eskom.

Project Description
This is the second-biggest infrastructure project being undertaken in the Western Cape and is part of the Olifants River Water Resources Project. 

The Clanwilliam dam was built in 1935 and was raised to its current level, with a storage capacity of 128-million cubic metres, in the 1960s.

A feasibility study completed on the project in October 2007 found that raising the wall by 13 m is technically feasible and economically viable. The study also found that the dam needs to be strengthened.

The proposed project will improve the safety of the dam and increase the yearly yield of the dam by 69.5-million cubic metres, of which a portion will be used to assist with the development of resource-poor farmers.

The project will include:

• remedial works to the dam’s foundations;
• the raising and realigning of portions of Old Cape road;
• raising the Algeria road crossing over the Olifants river;
• protecting the N7 towards Citrusdal;
• maintenance of farm roads and residences along Renbaan road;
• upgrading and expanding the conveyance network downstream of Bulshoek dam; and
• other affected infrastructure, including a hydropower plant.

Potential Job Creation
The project has the potential to create about 3 800 permanent jobs.

Capital Expenditure
The project is estimated at R3.5-billion.

Planned Start/End Date
The project is expected to take four years to complete.

Latest Developments
The first trial blasting has been undertaken at the Clanwilliam dam construction site.

This will start hard-rock excavations and formally activates the construction to raise the dam wall after years of unprecedented delays.

In total, 116 holes were drilled in preparation for the blasting activity, with every hole having an average depth of 4 m, with 920 kg of explosives used for the blasting exercise, which resulted in a total volume of hard-rock excavations of 1 253 m3.

Before the blast, a trial blast had to be done to determine parameters of future blasting activities in line with security of surrounding infrastructure, mainly the dam, and ensure that there was no damage to the dam, and that it remained safe and intact.

Prior to the execution of trial blasting, the blasting subcontractor submitted blast designs to the engineer and approved professional person (APP) for approval. The APP, through consultation with a third-party blasting specialist, approved the designs , considering aspects such as no blasting within 100 m from the dam wall, unless it is controlled blasting.

With the blasting exercise, the hard excavations have started on the left bank and regular blasting activities can be scheduled almost monthly. All excavations remaining on the right and left bank are hard excavations, and blasting will take place as approved and scheduled.

Blasting will continue until all hard excavations are completed on both banks while other activities, such as stripping the overburden at the quarry area and widening of the N7, are under way. 

Key Contracts, Suppliers and Consultants
None stated.

Contact Details for Project Information
Department of Water and Sanitation Director media liaison Wisane Mavasa, tel +27 12 336 8264 or email mavasaw@dws.gov.za.