Although development rights were originally approved for 315 erven, the design team completely re-configured the layout to take environmental factors into account and to optimise the potential of this unique site adjacent to the Papkuilsvlei wetland system. The final layout has only 224 erven.
“The success of this project was due to an exceptional client and hisinvestment in the project team,” says landscape architect Tanya de Villiers. As a result of the lack of precedent examples in South Africa, members of the project team were taken on an overseas trip to study inspiring developments and to learn from numerous successes and failures there. The layout was a team effort, with inputs from the urban designers, architects, planners, ecologists, environmentalists and landscape architects all taken into account prior to submission of the subdivision plan.
The site has an exposed coastal climate, with high winds in both summer and winter. In addition, the salt content in the coastal sands means that portions of the site have elevated sodium contents, placing significant restrictions on the choice of plant material.Another factor to consider is that the micro-climate will change significantly once the houses are built, resulting in the final plant choices being severely tested at present.
The detailed aesthetics of the roads, bridges, ponds, boardwalks, external lighting, signage and open space design was led by the landscape architect, ensuring that the project was design-driven.
The landscape design incorporates a variety of bird habitats – the densely reeded lake edges, shallow sandy areas along the shore for wading birds and numerous islands. Numerous bird varieties have already been attracted to the site since the project has been completed, including a new resident pair of pied kingfishers.
A network of paths, boardwalks and jetties create a varied link across the circulation ponds and provide access to the lake. Approximately 750 linear metres of boardwalk, 150 m2 of decking and kilometers of pathway have been incorporated into the design. The boardwalks, jetties and decks were constructed of Balau timber and H5 water-treated pine poles with stainless steel fixings throughout. The natural weathering effect of Balau timber complements the Cape Cod building style and due to its dense quality, is hard-wearing and requires no maintenance.
Besides the numerous jetties and decks provided, the development also sports a communal multi-functional boathouse, so that the lake can be fully utilised for non-motorised boating and canoeing.
Lighting has been kept to a minimum, with restricted downlighting and landscape lighting incorporated where necessary. Signage which is illuminated at night was specially designed for the development by the landscape architect.
Two types of paving were developed specifically for use at Lake Michelle by Pavatile, at the request of CNdV Africa. These were the PlazaBlok™ and PlazaCobble™ ranges. Over 14 000 square metres of these products were used and their modern tile-like appearance does not try to emulate traditional stone references. These two product ranges include many modules and one from each range was used to accommodate the many paved spaces at Lake Michelle, which on the one hand function as driveways and roads and on the other hand as community walkways and courtyards. The larger PlazaBlok module was combined with a smaller PlazaCobble module in a formation which became known as the Stacker™ Pattern which diffuses the direction of the grouting lines, facilitating changes in direction, such as are typical at intersections. Square-off modules were developed so that the need for cuttings was significantly reduced at the edges of straight roads. The pattern also assisted in ensuring the structural integrity of the installation because it locks well due to the reduced length of grouting seams.
In addition, special corner modules ensured a neat installation in centre islands and culvert blocks were developed for bridge edges. Seating modules were developed for use with the gabions devised by the civil engineers, De Villiers Sheard. Heavy-duty EdgeBlok modules were used as paving blocks on bridges. Many of these new products cater to specific engineering needs while offering the decorative features of cast concrete.
Environmentally sensitive approach and ecosystem services
Central to the entire project was the need to sustain and augment the lake environment. Specialist freshwater ecologist Dr Bill Harding of DH Environmental Consulting (who has been involved with aquatic ecosystem management at Lake Michelle since 1998) was commissioned to advise on a range of issues relating to the sound functioning of the lake ecosystem. The re-design of the development footprint was driven by the need to accommodate existing wetlands and to provide linkages between these and the adjacent SANPARKS conservation area.A specific aspect which required close interaction between the engineering and aquatic components was a specially designed causeway crossing for a wetland corridor. The aquatics component included detailed studies of the groundwater, botany, fish, mammal and avifaunal elements.
The team led by DH Environmental Consulting identified the need to provide a series of new linkages between the existing lake and the conservation area. In consultation with the project managers, these were designed as wetland corridors fed by artificially circulated water from the lake. This approach has not only significantly augmented the extent of the erven water frontages but has increased the range of aquatic habitat and ecosystem services on the site. As such, the aquatic ecosystem design constitutes a substantial improvement compared to what previously existed on the site. A water quality model was used to identify the impacts of the increased number of erven around the lake.
Monitoring of the lake condition, undertaken since the pre-construction phase, has been the responsibility of AVDS Environmental Consulting, under the supervision of DH Environmental Services.
The Green Perspective was contracted to supply and install the landscaping and irrigation at Lake Michelle.
Comments Richard Mathieson: “I recently attended a SALI Awards presentation and was intrigued by the number of entries that were said to have been constructed under harsh conditions. Although some warranted such comments, I was left unsure as to what ‘harsh conditions’ actually meant. Then we started work on Lake Michelle, and I realised that nothing I have ever done in my career so far prepared me for the harshness of this site. Our team finished on the project with enormous respect for the plant material and clearer ideas on how to landscape in the Cape.”
In the process, the following lessons were learnt, according to Mathieson:
- landscaping in such an environment takes far longer to develop. From environmental re-vegetation to a seasonal planting programme that will eventually develop into the desired landscape should ideally be a period of 3-5 years;
- the prevailing conditions were not suitable to tree planting, yet due to the client’s request, we planted large trees that came out of “soft nurseries” into extreme conditions. Again, if we had approached the landscaping with a long-term mindset, we could have prepared planting pockets to protect the upcoming tree planting;
- acclimatisation of all plant material to suit the site is paramount and should have been included in the process;
- procurement of plant material was a major problem and an issue that will need resolution in the new year.
With regard to the irrigation, programming problems were apparent immediately. “We had partly completed the first phase of planting, including most of the irrigation, but the supply was coming from an area that was still to be constructed in later phases. We made arrangements to use the lake’s water, but as the levels dropped during the hot season, the salt content climbed rapidly, something we noticed only later on. The issue of prevailing drought did not help matters either,” says Mathiesen.
After using the lake water, it was noted that the plants were not responding and were in fact yellowing. An analysis of the water was carried out and The Green Perspective’s fears were confirmed, namely that the water was unsuitable. They then had to cart water in with tankers during the hottest and windiest period of the year. Fortunately Mother Nature is extremely forgiving and the landscaping has started to perform well. Nevertheless, project delays meant that they had to plant again in the hottest time of 2005, but then the water restrictions were relaxed and they were able to use a clean water supply. Despite these factors, this kind of environment results in the landscape responding very slowly to repairs, so any kind of disruption would be detrimental.
Barring a few of the issues raised above, Mathieson believes that this landscape, if maintained sensibly, will be a testing ground for the number of landscapes in similar conditions that will be developed in the future. In the short term, Lake Michelle’s landscaping will need a high level of input but if protected and managed well, this will decrease over time.
The issue of irrigation is still a problem and “I do not have the answers to it, except to say that we need a rethink in this regard,” he says. Possibly, if the approach to seasonal planting is followed, ie plant in autumn or early winter, then less stress will be placed on the plant material.
Plant rescue and propagation programme
Although the site had previously been disturbed and was almost entirely covered in Port Jackson, Rooikrans and myrtle, some of the lake edges and moist areas contained plants that were identified for rescue prior to earth-moving.In total, 50 000 plants were removed from the site and taken to a local nursery where additional numbers were propagated for use on the site. Islands in the lake were cleared of aliens, leaving only a few dead trees for the nesting of birds, and were then re-vegetated with endemic species.
According to Brett Young of Bayflora Indigenous Nursery (who undertook the plant rescue and propagation programme), the most challenging aspect of the project related to the environmental issues and the difficult local micro-climate. As a result, the use of locally indigenous plants was seen as a way to ensure sustainability of the landscape, reduce the environmental impact of the development and link it with the surrounding natural areas.
Implementing this would be a problem, however, as many locally occurring wetland plants would not be available from local nurseries, especially in the vast quantities required. As a specialist contract grower, Young met with the landscape architect on site in April 2004 to discuss a contract propagation order that would include an extensive ‘search and rescue’ component. After being appointed, he and his team started rescuing and propagating wetland plants that occurred naturally on site. The species list included Juncus sp, Chondropetalum sp, Bulboschoenus maritimus, Schoenoplectus scirpoides, Carex clavata and Scirpus nodosus.
In total, over 50 000 plants were rescued and propagated and 2000 new trees were introduced. An additional 35 000 plants were supplied to Green Perspective, the landscape contractors. Says Young:“I believe the success of the project is due to several things. Firstly a fantastic design concept by Tanya de Villiers and the CNdV team, secondly a developer who recognised the importance and value of a quality landscape, and invested in its implementation, thirdly, forward planning that enabled my team to rescue, propagate and produce sufficient wetland plants for the landscape and last but not least, the hard work of Green Perspective, the landscape contractors.”
Storm water and road design
Storm water run-off from roads is led into reed bed channels running along the length of the roads in order to help clean the water before it enters the lake. This unique design completely obviates the need for any underground piped storm water system and creates approximately three hectares of additional reed beds and channels. Road widths have been kept to an absolute minimum and semi-permeable gravel parking areas are incorporated to reduce hard surface run-off. The design of the roads is specifically focused on slowing down traffic in order to create a pedestrian-friendly environment.
Lake Michelle’s setting alongside an existing lake and wetland system meant that the new pond system had to be incorporated in such a way that the two systems could interact with each other in a controlled environment. As the existing wetland is protected, any new development is not allowed to impact on it in any way.
The lining system for the new water features blends in with the surroundings and also provides a water-tight barrier between the new ponds and the existing wetland. A 1,0mm thick Vitaline liner was installed in the excavated ponds and one of the design criteria was that a ‘soft edge’ should be incorporated, in which reeds and plants could be planted so that the liner itself would not be visible. This ‘soft edge’ design allowed for soil to be placed on top of the liner without slipping off once it (the soil) was saturated.
There are many scenic walkways which follow the perimeter of the ponds and project out into the water. The liner design incorporated the numerous poles which were needed to hold up the walkway system. These poles were jetted into the soil beneath the liner and then each pole was sealed to the liner using a geo-synthetic clay liner held in place by a confining layer of sand cement.The ISO quality assurance procedure meant that each heat-welded joint and seam in the geo-membrane was tested to ensure a water-tight installation.
Information in this article supplied by CNdV Africa,DH Environmental Consulting, The Green Perspective, Bayflora Indigenous Nursery, Engineered Linings and Deck King.
Photos by C & D Heierli Photography, supplied by Tanya de Villiers of CNdV Africa