When the Luipaardsvlei Landfill site in Roodepoort, Gauteng, needed capping with a Compacted Clay Liner (CCL), it was decided to hydroseed the slopes in order to create an environmentally compatible look.

Once King Civil Engineering Contractors had constructed the 300mm Compacted Clay Liner (at Mod AASHTO 95), it was covered with a 200mm layer of topsoil. It soon became obvious to Pro-Plan Consulting Engineers that the steep gradients of the landfill site would render compaction of the topsoil impossible. The first rains to fall on the hydroseeded slopes would inevitably lead to complete erosion of the topsoil.

Engineered solution

When engineered fabrics company Kaytech’s Winnie van der Merwe was contacted for advice on the problem, she suggested that its biodegradable SoilSaver product would be the ideal solution. SoilSaver is a woven 100% jute yarn comprising a coarse 65% open mesh structure, supplied in compressed bales that can easily be carried up a slope by one person. Once installed, hydroseeding can take place.

On completion of the project, 60 000m² of SoilSaver, pegged down by means of four wooden stakes per square metre, had been positioned on the steep slopes. The fabric is flexible so that it can be draped over any ground surface contours or irregularities.

Horticultural advantages

Trials have proven that one of the main advantages of using SoilSaver is that it retains up to five times its own weight in moisture, a vitally important factor for the germination and development of seeds. The space between the jute strands allows for plant growth and penetration of light, while also protecting the seedlings from direct sunlight.

In early spring, the landfill slopes were seeded with a combination of Teff, Midmar and Arogastis grass seeds. During rainfall, the jute strands of SoilSaver not only absorb any splash impact, but trap the seeds and soil particles thereby reducing run-off velocity and preventing soil erosion.

Environmental advantage

Properly secured, the fabric cannot be lifted by wind, flowing water or growing plants and after about one year (by which time vegetation is well established) it decomposes. Since it contains no toxins, plastics or pollutants, the decomposition of SoilSaver is ecologically safe, with its fibrous residue actually being beneficial to the soil structure. Unlike other natural materials, as it decomposes, the product does not absorb valuable nitrogenous reserves in the soil.

Although it’s simple to install fabric that prevents erosion and does not require skilled labour, Kaytech provided a one-day on-site training course for the local work team. To accredit their training, each labourer was presented with a much appreciated certificate and King Civils was able to submit these certificates with their next BEE certificate application.

With the use of cost effective erosion control, the Mogale City Municipality not only saved money but is assured that the green credentials of its Luipaardsvlei Landfill site will stand the test of time.