Precast concrete grass blocks line drainage channels

Drainage channel sections have been lined with grass blocks supplied by CMA member CEL Paving Products on a 12km section of the old Malmesbury road in the Western Cape. The road, which runs between Philadelphia and Kalbaskraal, is being completely rebuilt with new layer works, fence lines and drainage, and is due for completion in May 2021.

The project’s professional team includes consulting engineers MPAMOT, a joint venture consortium comprising Amandla Construction and Umzali Civils, and a local paving contractor, Esau Holdings. Jako Kriel of Amandla is the senior member on site and is being assisted by Les Groenewald of MPAMOT and François Lourens of Umzali Civils.

CEL supplied 10 000m² of grass blocks, which were used to line some of the drainage channel sections on both sides of the road. The blocks were laid by Esau Holdings, which employed members of the local community, trained by Umzali Civils. The blocks were laid two abreast on one in two slopes on either side of a 1 000mm x 125mm concrete base.

Umzali site agent Lourens says that once laid, the blocks were filled with soil for greater stabilisation and plant growth.

“The blocks were installed to prevent erosion and, being open-faced, will allow water infiltration between the block openings. This controls water flows, especially during heavy downpours, and assists with flood prevention,” he explains.

The channels drain into stormwater pipes and box culverts which, in turn, drain into the Diep River to the west of the new road. Water from east-lying channels drain under the road via culverts into stormwater pipes and box culverts. From there, it flows overland to the river.

(Left): A water channel section paved with grass blocks supplied by CEL Paving Products.