DV Harris Water Works (61 Pipeline)

DV Harris Water Works (61 Pipeline)

A R92 million bulk pipeline stretching 5.7 km has been laid to boost the water supply from Pietermaritzburg to Durban by 1 024 litres per second.  Umgeni Water, the bulk water provider, needed to improve the water supply to both eThekwini and Msunduzi Municipalities and commissioned J&G to design a pipeline to boost the connection from the Midmar Water Treatment Works to World’s View Reservoir.  The previous system supplied water at a rate of 130 Ml/d but the ultimate design called for a total of 330 Ml/d.

Various options for the route of the pipeline were looked at from technical, geotechnical, risk, economic, land ownership and environmental points of view and discussed with the affected land-owners and stake-holders.  The final route takes the new pipeline from a bulk supply line near Ferncliffe, a natural reserve adjacent to the DV Harris Water Treatment Works, through the Queen Elizabeth Park which is home to the headquarters of Ezemvelo KZN Wildlife and across the newly established Victoria Country Club Estate, under the N3 highway as it snakes down Town Hill, from Hilton to Pietermaritzburg, and finally, along the Hilton mist-belt grassland biome up to the existing Clarendon Reservoir.

From this point the existing 787mm diameter and new 900mm diameter pipelines were conjoined and the new 1 200 mm diameter pipeline was laid over 1 km and connected to the inlet at World’s View reservoir.  The 1 200 mm outlet followed the same route as the incoming line for 500 m and then deviated to link up with the existing supply lines to Umlaas Road which delivers water to eThekwini Municipality in Durban.

The contract comprised the following:

•   Laying of 3 835 m of continuously welded 900mm nominal diameter (ND) steel pipe, supplied by the Employer, from a connection near DV Harris WTW to Clarendon Reservoir.  Wall thickness varies from 6.35 to 8.4mm.

•   Laying of 1 040 m of continuously welded 1 200mm ND steel pipe, wall thickness 8.1mm, from Clarendon Reservoir to World’s View inlet.’

•   Laying of 800m of continuously welded 1 200mm ND steel pipe, wall thickness 8.1mm, from World’s View Reservoir to the Umlaas system tie-in point.

•   Six tie-in points to the existing bulk water systems – two at DV Harris, one at Clarendon Reservoir, two at World’s View and one at the beginning of the Umlaas supply system.

•   A confluence chamber and four meter chambers.

•   Laying of 900 mm diameter pipe through two 1 680mm concrete sleeves under the N3 and R103 of 76m and 20m length respectively.

•   Restricted excavation and pipe laying along 800m of Mistbelt Grassland on one side and the existing 787 mm diameter ’60 pipeline on the other.

•   30 air valves, 8 scour valves and 7 Isolating valves

•   Road crossings - 3 gravel road crossings and 3 crossings of brick-paved roads

•   One 30m long pipe bridge and two river crossings

•   Pipeline Sundries including environmental management.

•   Environmental rehabilitation (by selected specialist sub-contractor).

•   Cathodic protection system (by selected specialist sub-contractor).

J&G was responsible for all design, contract administration and construction supervision elements of the project and Icon Construction was the contractor.