In 2011 Rhino Construction Limited purchased the nationally advertised tender as part of a sealed bidding process for the Nanka Landslide Erosion Gully project. The Federal Ministry of Environment observed the procurement process.
As a result, a total of 16 competing construction companies submitted applications. Of these, 14 companies submitted tenders for the project in June 2011. The procurement process, conducted under a sealed bid procedure ended in the public bid in July 2011. Prior to a further decision period, prior to the award of the final construction contract.
Enviromesh assisted throughout the Nanka Landslide Erosion Gully project, both at the initial tender stage with engineering and technical advice as well as gabion requirements for the scheme as a whole. Therefore, the Nanka Landslide Erosion Gully project would need 4,000 no. gabion mesh baskets, 280 no. mattresses and related wire accessories; together with an in-depth training programme.
Phase 1 of the project provided gully base protection through a combination of both hard and soft construction solutions. This comprised of two mass gravity gabion walls with mattress protection coupled with large-scale embankment planting on the slopes.
Phase 2 is planning to provide stability to Nanka and Oko embankments which will complete the scheme.
The main challenges:
- Local geology: fragile, erodible and sandy soils, subject to the effects of extreme erosion caused by storm-water run-off.
- Extremes of the local climate: here it is typically tropical with six months of heavy rains.
- Training the local workforce: to construct and install the retaining walls.
- Access for heavy machinery: break into the gully through the Nanka side edge and create access to allow for the delivery
of materials on site
- Working with heavy machinery: to excavate the site and prepare wall foundations; excavating drainage channels; with a building programme spanning six months of heavy rain.
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