The history
Built on the extraction of timber and gold, Knysna developed as a rough-and-ready town with an industrialised waterfront. The gold was short-lived but, even after the town evolved into a major tourism destination, the timber industry continued to dominate and, from the 1920s, Thesen Island was the centre of the timber processing industry. The power station, which was built on the island in 1939, was fuelled by the sawdust and wood chips generated by the sawmills. Not only did it provide jobs for the local community and power to Knysna and Plettenberg Bay, it also fed into the Eskom national grid. By the late 1990s this island was 96 hectares of underutilised and somewhat degraded land – but in a prime location in the biodiverse Knysna Estuary.
This presented any potential developers with a range of challenges, and Dr Chris Mulder, a modern-day pioneer who has embraced the adventurous spirit of this seaside town, rose to the challenge, and achieved the triple bottom line of social, economic and ecological integration and sustainability in the design and development of the Thesen Islands project. The design work commenced in 1991 when the then owners, Barlows, asked CMAI what could best be done with the island. Seven years and 26 design concepts later, approval of this environmentally sensitive project was obtained in 1998. Construction started in September 2000, and eight years later the entire project of 605 residential units and the commercial area with two hotels and five restaurants was completed and sold out. No wonder CMAI claims this project as their flagship after 15 years of constant design and construction implementation.
Decontamination
As a result of decades of industrial activity, the low-lying island was polluted by chrome, arsenic, creosote and copper. This highly contaminated soil was encapsulated and sealed with sodium bentonite cut-off walls and blankets, and capped with topsoil and replanted. The area was rehabilitated by creating wetlands and planting trees, shrubs and grasses along the 11 kilometres of canal bank.
Ecological rehabilitation and conservation
The Knysna Estuary is an important and diverse one, with mudflats, sandy areas, rocky sections, deep water, extensive saltmarsh areas, and subtidal sea-grass beds. The island harbours endangered bird, plant and marine life including the Knysna seahorse( Hippocampus capensis).
The solutions to the ecological issues were pure genius. Before any construction was done, a complete assessment of the status quo of the lagoon was done. This baseline assessment gave the developers something against which all construction activities could be assessed and measured. Only then was the system of canals dug, based on the approved CMAI design. The excavated soil was used to raise the level of the newly created islands by 1.8 metres to a height of 2.8 metres above sea level.
The canals were constructed using rock mattresses and gabions to establish the canal edges and bottom lining. Fortuitously, this created an ideal habitat for the seahorses, whose population has subsequently increased. The water flowing through the marina is open to the estuary so it moves with the tides, thus ensuring constantly changing clean canal water, providing an ideal habitat for a host of marine creatures. This habitat and biodiversity creation contributed immensely towards CMAI Architects’ s winning the IFLA award but – even more importantly – it has also resulted in Thesen Islands’ s ever-increasing and enduring property values.
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