Project Name: Kupferberg Landfill Hazardous Cell 2 and General Cell 2

Client: City of Windhoek, Windhoek, Namibia

Project Description: The Contract comprised the design, site supervision, quality assurance and contract administration of a new hazardous cell (Cell 2) as well as a new general cell (Cell 2) at the Kupferberg Landfill site. The Site is situated approximately 9 km south-west of the Windhoek CBD along the Gamsberg road.

As part of the contract, new contaminated storm water channels along the toe of the waste bodies were designed as well as a new contaminated storm water storage dam. The existing leachate lagoon had to be demolished and reconstructed in a new area in order to optimize available area for waste disposal. The new hazardous Cell 2 was constructed in its place. The entire new hazardous Cell 2 was constructed as a piggy-back on top of old waste and portions of the new general Cell 2 are also on old waste.

Also part of the Contract was the upgrading of the infrastructure which included the construction of a public drop-off facility, a wheel wash, a blending facility as well as a new workshop building.

The layer works for the landfill comprised of the following (from top to bottom):

Hazardous Cell 2 (10,100m²):
•    300mm thick leachate collection layer of 38mm crushed stone
•    200mm thick sand protection layer on floor and 1000g/m² non-woven geotextile as geomembrane protection layer on the side slopes.
•    2mm HDPE geomembrane supplied by NAUE, Germany
•    Bentofix NSP 4900 geosynthetic clay liner supplied by NAUE, Germany
•    Secudran XX5 – 141/141 for leachate leakage detection, supplied by Naue, Germany
•    Bentofix NSP 4900 geosynthetic clay liner supplied by NAUE, Germany
•    Rip and Re-compact 150mm thick in-situ material or fill with 300mm thick sand compacted sand for excavations in waste
•    Kaytech Rock PEC 100/100 reinforcing grid for excavations in waste

Leachate Lagoon (2,500m²):
•    200mm thick geosynthetic multi-cells filled with cement stabilized sand
•    2mm HDPE geomembrane supplied by NAUE, Germany
•    Bentofix NSP 4900 geosynthetic clay liner supplied by NAUE, Germany
•    Secudran XX5 – 141/141 for leachate leakage detection, supplied by Naue, Germany
•    Bentofix NSP 4900 geosynthetic clay liner supplied by NAUE, Germany
•    Rip and Re-compact 150mm thick in-situ material or fill with 300mm thick sand compacted sand for excavations in waste
•    Kaytech Rock PEC 100/100 reinforcing grid for excavations in waste

Contaminated Storm Water Dam (8,600m²):
•    200mm thick geosynthetic multi-cells filled with cement stabilized sand
•    1,5mm HDPE geomembrane supplied by NAUE, Germany
•    Bentofix NSP 4300 geosynthetic clay liner supplied by NAUE, Germany
•    Secudran XX5 – 141/141 for leachate leakage detection, supplied by Naue, Germany
•    Rip and Re-compact 150mm thick in-situ material

Layerworks underneath Concrete Blending Facility (300m²):
•    300mm thick leachate collection layer of 38mm crushed stone
•    1000g/m² non-woven geotextile as geomembrane protection layer
•    2mm HDPE geomembrane supplied by NAUE, Germany
•    Bentofix NSP 4900 geosynthetic clay liner supplied by NAUE, Germany
•    Secudran XX5 – 141/141 for leachate leakage detection, supplied by Naue, Germany
•    Bentofix NSP 4900 geosynthetic clay liner supplied by NAUE, Germany
•    Rip and Re-compact 150mm thick in-situ material

General Cell 2 (15,000m²):

•    200mm thick sand protection / confining layer
•    Bentofix NSP 4300 geosynthetic clay liner supplied by NAUE, Germany
•    Rip and Re-compact 150mm thick in-situ material or fill with 300mm thick sand compacted sand for excavations in waste

The leachate collected in the hazardous cell is drained into a pump sump outside the cell from where it is pumped into the leachate lagoon.  Here it is contained for evaporation or can be pumped to a top loader facility should it be required to be tankered away.

The new hazardous cell, leachate lagoon and blending facility each have their own leachate leakage detection system with a dedicated monitoring / inspection sump.

All the storm water run-off from the waste body side slopes drain into a contaminated storm water storage dam. From here it can be pumped to a top loader facility to be used for dust suppression should it be required.

A detailed design was also done for all the future development of the site which includes the next hazardous cell, future general cells, mess facility, upgrade of the weighbridge area, new office building and upgrade of the entrance area.

Location:
South 22 38 13  East 17 01 50

Contract Data (Construction)
Contractor: KL Construction (Civil), Engineered Linings (Geosynthetic lining work)

Commencement date: 22 March 2007

Completion date: 3 October 2008