Work is well underway to open a second phase – Bergendal – at Bloemfontein’s sought-after Woodland Hills Wildlife Estate residential development. Raubex Infra’s civils division is currently putting vital infrastructure such as storm water pipes, water reticulation, sewers and streets in place.
According to Raubex Infra site agent, Jaco de Jager, the work will make way for another 84 properties of 1,000 m2 each and includes the upgrading of an access road from the provincial R700 route nearby to the Bergendal Gate as well as some enhancement to the R700 itself. On the Woodland Hills site, work is underway to complete 21,000 m3 of mass earthworks, 22,000 m3 of layer works, and 6,300 m3 of trench excavation.
“The rocky surface conditions in the area required us to conduct extensive blasting in the early months of the contract, to ensure that pipes could be laid to the correct depth,” says de Jager.
The work also includes excavations for slabs and drainage, and about 33,000 m2 of asphalt surfacing will be laid.
In line with the development’s environmental priorities and growing concerns about South Africa’s water scarcity, Raubex Infra will also be installing a grey water line from the nearby sewer station. This water source will be used for irrigation purposes and will reduce the estate’s environmental footprint while helping ease pressure on the municipality’s treated water capacity.
Another initiative has been to make full use of the blasted surface rock. This is broken further by excavator-mounted hydraulic breakers before being fed into the on-site crushing plant for G2 aggregate production.
“We use the minus 75 material as backfill for the pipe trenches, and also supply a minus 200 fraction which will be used during construction of the development’s dam wall,” he says. “We are also using selected stone to create a G2 material that is used for the road base.”
The low-traffic roads on the estate are constructed with three layers, a selected layer, an upper selected layer and premix asphalt on the surface. Instead of creating the base on the road using a grader and water bowser, the material is mixed in an on-site pug mill supplied by Raubex Infra’s plant division.
“The pug mill efficiently creates the mix with the required 8% moisture content, eliminating the need for conventional water spraying on the road,” de Jager says. “It also pre-mixes G1 material for our enhancement work on the high-traffic R700 provincial road.”
To ensure that stormwater is adequately channelled from the new development’s access road, there are barrier kerbs with purpose-designed kerb inlets. Precast items for the inlets are being cast on site by Raubex Infra. To ensure the effectiveness of the storm water system, a 300 mm concrete channel will carry water away and prevent ingress.
The access road is built to a robust design given the water-flow conditions in this hilly area. The minus 200 fraction pioneer rock layer is followed by a selected layer, upper selected layer, sub-base and base with pre-mix asphalt on the surface.
Leveraging the power of technology, a global positioning system (GPS) on site allows the two full-time surveyors to set out points and levels, constantly monitoring the accuracy with which the plans are implemented.
Having begun work in October last year, Raubex Infra’s contract at Woodland Hills is due for completion in the third quarter of 2018.