Landscaping around the Life Science Development (LSD)
Natural Habitat
Critically endangered Cape Flats Sand Fynbos – dominated by Thamnochortus erectus and Hellmunthia mebranacea with a high concentration of geophytes such as Ferraria crispa, Brunsvigia orientalis, Morea fugax, Lachenalia rubida, Babiana ambigua, Babiana tubulosa, Gladiolus carinatus, Geissorhiza tenella the majority of which are now extinct or have populations less than 5 in the main CFNR(and the extension agreed as part of the mitigation for development of this site). Scattered scrubs include Euclea racemosa, Rhus spp, Metalasia muricata, Salvia africana lutea and Helichrysum crispum.
Geology
Mostly neutral to acid substrate. Of the 1.6 ha that is likely to be cleared half has a pH of 7.0-7.5, 5 000 sq m has a pH of 6.5 to 7.0 and a further 2 000 sq m has a pH of 6.0-6.5 and a small patch of 1 000 sq m has a relatively high pH of 7.5-8.0. Throughout the area a high water table exists at typically 1.2-1.5m below surface, but in the north west corner it drops to 800mm below the surface. The profile of organic content suggests that no root/organic matter goes below 1.5m indicating that the water tables does drop significantly during summer months. It represents a paleo-drainage line and in places laterites are close to the surface and the building is perpendicular to the natural drainage.
Record of Decision (ROD)
The Basic Assessment Report requested 0.89 ha (8 900 sq m) to be developed in a 1.9 ha precinct of natural vegetation. The expected footprint of loss of endangered natural vegetation has increased to 1.3 ha. However, so little natural vegetation is left around the building and the high water table suggests that a detention pond should be constructed to manage this. The ROD specifies that no ground water to be polluted, and that the site must be re-vegetated with locally indigenous species from the Dog’s Leg and CFNR (where appropriate). A Search and Rescue was conducted by Deon van Eeden of Vula Environmental Services. Top soil to a 200mm depth is to be relocated and used to restore degraded extension areas of the Cape Flats Nature Reserve CFNR (where the mole-rats play). Please note this is NOT a Biodiversity Offset as envisaged by DEA&DP.
Post-construction re-vegetation
Area for Replanting Area sq m
Road (soft/bedding landscape) 2 000
Entrance (planter + bedding) 400
Small north-east dune 350
Main Dune - Modderdam Road 1 600
Roof Garden Upper 300
Roof Garden Middle 400
Roof Garden Lower 600
General landscaping 7 500
New Car Park (west) 2 200
Container Wall 4m h X 50m 200
Total Area: Landscaping 15 550
Approximately 1.555 ha needs to be landscaped with neutral to acidic loving, locally indigenous species for ROD compliance. Car Park area would naturally have supported Dune Thicket vegetation which is more easily grown and established.
Concerns
The construction will require enormous quantities of fill material. The building is to be build-up approximately 2.1 m relative to current surface to align with existing roads and other UWC buildings which together with the removal of the top 200 mm will require nearly 20 000 cubic metres of infill for the building alone. The construction of the artificial berms which rise to about 5m and will need more soil as will the various roof gardens over the Learning Centre and for the retaining wall along the service entrance. All introduction of soil pose the risk of promoting invasive species. Given the very extensive negative publicity (e.g. type in Google the words “life+science+uwc” will return first the high controversy around this development) every effort is now necessary to comply with the rest of the ROD with respect to use of locally indigenous plants. It will be impossible to introduce suitably acidic soil. Landscaping should not be dependent on long-term irrigation.
Recommendations
· A large quantity of top soil should be “stored” in the area north east of the development currently under lawn. Preparation will use “Roundup” (a contact, systemic, non-residual herbicide) to kill the grass. This top soil should be spread to a depth of 400mm layer, stabilized with cut vegetation from the site and over-sown with annuals to maintain biological activity (irrigation will be required but the site is currently irrigated).
· Investigate developing an artificial detention pond (cost savings since the acid/neutral sand can be stored and used for replanting). This will help supply much needed acidic soil for re-establishing locally indigenous species. The lower surface around the pond with its wet soils will speed re-establishment and promote introduction of bird/amphibian biodiversity.
· Where the soil was stored, attempt to establish a locally indigenous Cape Flats Sand Fynbos garden that integrates with the LSD landscape with information boards for awareness/education. Roof Gardens should be used for rescued geophytes with restio/sedges planted with washed gravel beds to reduce water use and suppress any fire risks.
· That researchers, CFNR managers, construction teams and subcontractors together with landscape architects and staff of the BCB department work together and apply scientific principles for an ecological reconciliation of the this area.