Solutions for Reducing Borehole Costs in Rural Africa - International ...

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The drilling contract periods are oftenuncertain and afford little security offuture work as holes to be drilled areoffered in small numbers. In suchan unpredictable market, lendinginstitutions default to demanding 100percent recoverable collateral in theform of property, land, or externalsecurities.The number of capable, indigenousAfrican contractors continues to grow,though they operate at low capacities.Many other start-ups fail as a result ofthe handicaps and high risks that standin the way of success. Of particularconcern is the awarding of contractson the basis of political connections orcash inducements, rather than on abilityto fulfill the contract.What drills in Africa?A borehole is a round hole thatpenetrates the earth’s surface to a levelwhere groundwater flows. The wateris pumped to a supply point on thesurface. Proper lining, sealing, cleaningand evaluation of the borehole areessential for tapping clean water.A drill rig is a tool that rotates a drill pipeand allows it to descend into, and behoisted out of, a hole in the ground. Itbasically consists of a steel frame, amechanism for rotating the drill pipe,and a hoist device. Some drill rigsare operated by complex hydraulic,mechanical, pneumatic or electricalsystems.Interestingly, procurement of drillingservices has customarily emphasizedthe technical specifications of drillingDrilling equipment graveyardequipment rather than the job in hand.Throughout the drilling industry, unduesignificance is attached to how a drillrig functions, diverting attention fromthe very job it is designed for - to drill aborehole (Box 1).The preoccupation with specifications ofdrilling rigs undermines the impact thatsmaller diameter boreholes can maketowards attaining the MDGs for watersupply and sanitation.Almost all government and privatesectorcontractors in Africa use heavy,truck-mounted drilling equipment. Thisequipment has the capacity to drilldeep and wide boreholes, typically 500meters and with diameters exceeding200 millimeters. Yet such equipment areoften deployed to drill holes only 30-80meters deep.Apart from the excessive technicalcapacity, the vehicle size renders theseequipment inappropriate to meet theneeds of rural communities.In the past four decades, twotechnological advancements haverevolutionized drilling of boreholes forwater supply: the down-the-hole (DTH)hammer, and the extruded plastic pipe.Down-the-hole hammerDTH hammers are pneumaticallyoperated tools that transfer high powerfrom an air compressor mounted on thesurface to a series of tungsten buttonsunderground, pulverizing the hard rock.DTH hammers were initially developedfor use in rock quarries as an economicway of drilling blast holes for explosivecharges.4
Solutions for ReducingBorehole Costs in Rural AfricaThe development and use of DTHhammer technology is still dominated bydemands of the mining and constructionindustries where production hammersdrill holes from 50 to 1,000 millimetersin diameter, 2 yet millions of water-supplyholes would not exist in India todaywithout the existence of this tool.Extruded plastic pipeExtruded plastic pipe can act as analternative to steel for some generalconstruction applications. The ease ofproduction, strength-to-weight ratios,resistance to corrosion, low cost perunit length, flexibility, and the ease withwhich they can be joined, threaded,and slotted means that plastics haveBox 1. Sample tender for drilling‘An all-wheel drive, truck-mountedrig, with a 15,000 kg capacity mast,capable of working with 6 m drillpipe. An onboard compressor, withwater-cooled diesel engine, capable ofdelivering 750 cfm air at 20 bar . . .’Instead of describing the equipment,the tender could be re-phrased to read:‘Required: a mobile set of drillingequipment capable of constructing4” diameter holes in crystalline rockto depths of 80 m, and capable ofaccommodating plastic surface casingpipe and pumping system to depthsof up to 25 m. Bidders must offercomplete equipment sets, inclusive oftransport and materials, to undertakethe construction of 1,000 boreholes infour years.’advantages over steel for many pipingapplications. They are also simple tohandle and transport.Pragmatically, current tools andmaterials to advance groundwatertechnology continue to be derived fromestablished markets in other industrialsectors.What defines thecost of drilling?Four elements define the cost of aborehole:1. The capital costs of constructionequipment – the drill rig, toolsand rig transport. The total outlayincludes costs of shipping theequipment to the country of use,including import taxes and financecharges. This initial purchase priceis amortized over the lifetime of theequipment, typically between 3 and10 years. The sum is then furtherdivided by the annual productionrate to determine a cost per hole orper meter.2. Material or consumable costs – welllining materials, cement, drillingmud, gravel pack (if required), fuel,lubricants, and maintenance. Theseitems are listed and calculated perborehole.3. Labor costs for the constructioncrew.4. Overheads – the provision ofcapital, administration, and logistics.The total sum is divided by theLow-cost hand-drlling techniqueannual borehole production rate todetermine a cost per hole or permeter. Assuming most organizationsdrill more than a single borehole, amethod to calculate the total revenueof an individual drilling operationfrom the overall revenue is required.Where is groundwaterlocated in Africa?The main geological formations in Africayielding groundwater are examinedbelow, with a brief analysis of theirpotential.Pre-cambrian basement orcrystalline rocksPre-cambrian basement or crystallinerocks underlie the ground inhabited by2Halco product range, 2001.5
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