Civil Engineering June 2021 | Vol 29 No 5

Civil Engineering June 2021 31 population of 3 244 and an average per capita consumption of only 78 ℓ per person per day. Since 2009, the water levels in the area have declined due to low rainfall and subsequent lack of recharge. In 2013 the town’s wellfield started failing rapidly, no longer able to meet the demand of 450 m 3 per day. BVi Consulting Engineers was approached to provide a solution. Being a groundwater project, Stellenbosch-based company GEOSS South Africa was contracted as a specialist groundwater consultant. An initial hydro census was performed and followed by two rounds of exploration drilling in 2014 and 2015. During this time, an emergency water supply system was rigged, and the town was placed under severe water restric- tions. The emergency system comprised a 40 km above-ground rising main supplied by three solar-powered borehole pump stations; the water being lifted through an elevation of 400 m. This system delivered 1.6 ℓ/s to the town. The reservoir outlets were shut off and water was only provided between 17:00 and 21:00 every evening. This situation continued until the middle of 2017. The exploration drilling project suc- cessfully drilled 35 boreholes, of which nine where suitable for use as production wells. The problem was that they were located in the Rheeboksfontein Valley approximately 30 km from the town and some 300 m lower than the town reservoirs. A feasibility study of various options was done and submitted to the Northern Cape Department of Water and Sanitation for funding through the Regional Bulk Infrastructure Grant programme. The project was approved for funding and construction commenced on 1 February 2017. The contract comprised the following works: Q Q Equipping of nine borehole pump stations with pumps, switchgear, and instrumentation Q Q 12.4 km of small diameter uPVC collector pipelines between new bore- holes and the collection reservoir Q Q A 944 kℓ sectional steel collection reservoir Q Q A booster pump station with capacity of 12 ℓ/s at a head of 310 m Q Q Rising main pipeline between Rheeboksfontein and Loeriesfontein over 21.680 km through an elevation of 300 m, consisting of 13 km of high- pressure ductile iron piping and 8 km of uPVC piping of various classes Q Q Water treatment plant at Loeriesfontein equipped with a set- tling tank, pressure sand filters, and a cascade aerator for the removal of hydrogen sulphide gas Q Q A 125 kℓ sectional steel elevated storage tank on a 10 m stand Q Q High lift pump station at the Loeriesfontein Reservoir Complex with a capacity of 20 ℓ/s at a head of 15 m to lift the treated water from the existing storage reservoirs into the elevated storage tank Q Q Medium voltage electrical power line over a total distance of 40 km Q Q Telemetry system to monitor and control pumps and reservoir levels. Figure 2 Exploration drilling in progress Figure 3 Typical borehole pump station installation