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

November 2004Field NoteSolutions for ReducingBorehole Costs in Rural AfricaApproximately 256 million people in rural Africa live without access to safe water supplies, in areas thatcould be appropriately supplied with water from hand-pumped boreholes. This field note contends thatthe current cost of drilled boreholes in Africa can be halved by relaxing borehole specifications in favor ofsmaller diameter bores drilled by more maneuverable, lower cost equipment.

SummaryFigure 1. Africa: Water Supply CoverageGroundwater is generally a readily available sourceof water throughout Africa. However, high boreholeconstruction costs are slowing progress on increasedaccess. Higher costs are largely a result of usingdrilling equipment with specifications that are greaterthan those required for the vast majority of boreholesneeded in Africa.Using high cost machinery and support equipmentleads to high borehole costs, which in turn results infewer boreholes being drilled. The smaller volume ofwork per drilling rig creates inefficiencies in equipmentusage, and results in increased overheads, driving upcosts dramatically.This field note contends that the current cost ofdrilled boreholes in Africa can be halved by relaxingborehole specifications in favor of smaller diameterbores drilled by more maneuverable, lower costequipment. The average cost of drilling a borehole canbe reduced from USD$6,000 to USD$3,000, and sometechnological applications could bring down the costto less than USD$1,000. These sizable cost reductionshave the potential to contribute to Africa’s attainmentof the Millennium Development Goals (MDGs) for watersupply and sanitation 1 and the livelihoods of millions ofrural Africans.Clearly, new approaches are required to drill the onemillion or so boreholes that will help Africa to meet theMDGs for water and sanitation. This can be achievedby adopting these new approaches:• Review and revise outdated national standards thatfavor conservative borehole designs• Develop an effective small business sector, madeup of African drilling contractors, based in ruralareas and spread amongst the communities theyare required to serve• Promote new, appropriate drilling technologies• Provide continuity of work for local businesses.Water supplycoverage0%–25%26%–50%51%–75%76%–90%91%–100%Missing dataSource: Global Water Supply and Sanitation Assessment Report, 2000Who drills in Africa?To understand borehole drilling in Africa, it is important toknow who is doing what, where and the equipment in use.Governments own, directly or indirectly, most of the drillingrigs in Africa, but drill fewer holes than other operators. Nongovernmentalorganizations (NGOs) and contractors ownabout half of the remaining machines in operation. Despitethe prevalence of appreciable market distortions, privatecontractors drill the greatest number of holes.Government departmentsGovernment departments responsible for drilling typicallyprocure equipment as donations from external supportorganizations, but may then lack the management skillsand resources needed to sustain a high-production drillingprogram. In many cases, the external support does not caterfor training, operations, maintenance and spare parts.1To halve, by 2015, the proportion of people without sustainable access to safedrinking water and hygienic sanitation.2

Solutions for ReducingBorehole Costs in Rural AfricaIn such circumstances, machines withcapacity to drill more than 200 holes peryear end up languishing in a brokendownstate, with no spares in stock orbudgeted for – effectively parked asidein perpetuity.International or local or iiiiior local NGOsBorehole drilling by NGOs is associatedwith a number of disadvantages. Whereregulations are inadequate, an NGOundertaking a drilling program may haveto define its own policy, measurementand construction criteria, and qualitystandards. Coordination with publicadministration and between agencies isoften problematic where NGOs operateindependently and autonomously.NGOs may also compete unfairly withlocal private contractors becausesome are able to import equipmentand materials duty free and to worktax free. This gives them a distinctcost advantage over private-sectorcompetitors who must pay local importduties and income taxes, and whoregard the advantage of NGOs as beingunfair.Certain NGOs are able to respond toemergencies quickly and independentlyby mobilizing borehole drillingequipment and providing water todisplaced and distressed populations.Many of such programs start off asquick-fix interventions, but continue tofunction on this basis for many yearsafterwards.International contractorsInternational contractors are typicallyforeign-owned, expatriate-managedbusiness ventures that remit profitsout of the countries from which theyoperate. The motivation is strong totake substantial contracts; capitalizewith large-scale, high-performanceequipment; employ skilled, expatriatestaff; and to aggressively chase highproduction rates for high-specification,high-value work.The host country receives neatlycompleted packages of boreholes,and only a few local employees inheritany transferable skills. The depth ofprofessionalism and level of investmentinvolved often overwhelms the capacityof NGOs, who generally do not competeat this level.At best, these companies wincontracts on the basis of their individualentrepreneurial skills and their inherentability to compete in the particularmarket. At worst, they obtain workbecause of visible or invisible links toconditional donor funding.Local contractorsSome local businesses are able toseize opportunities in borehole drillingand possess skills needed to win andinfluence award of contracts. But theyoften encounter difficulties mobilizingequipment, materials and skilledpersonnel required to undertake asustained construction program. Thecommercial risks involved in becominga drilling contractor are reflected inthe high cost of borrowing needed forfinancing such an enterprise.Figure 2: Africa: Water supply coverageFigure 3: Rural water coverage by region100801008060402006040200Source: Global Water Supply and Sanitation Assessment Report, 20003

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

Figure 4: Hydro-geological domainsof Sub-Saharan AfricaPreCambrian"basement" rocksVolcanic rocksUnconsolidated sediments(mainly Quaternary)Consolidated sedimentaryrocks (post PreCambrian)Lakessome 220 million people in rural Africa.Groundwater is mostly stored in theweathered overburden and feeds intofractures in the underlying rock. A goodwell site therefore needs to be locatedon an adequate depth of weatheredground. There must also be a goodchance of accessing a fractured layer inthe underlying rock. In some locations,weathering is deep and rock is heavilyfractured, making successful drillingeasy. In other places, the weatheringcan be thin and the rock fractureshard to locate, leading to very poorsuccess rates. Geophysics can helpto site boreholes by indicating areas ofdeep weathering and likely fractures,but this should be done in conjunctionwith a good common-sense appraisalof the site and location. Drilling to hitdeep weathering and shallow fracturesis the key: simply drilling deep is not asolution.Volcanic rocksIt is hard to generalize on drillingspecifications for volcanic rocks– on which some 45 million Africansare settled – as they often occurin mountainous areas. Generally,groundwater would be expectedbetween lava flows or in lava thatis heavily faulted or even porous.Sometimes water is located deepunderground and the water qualitycan be poor. Skilled geologicalassessment, possibly assisted withsome geophysics, can help to locategood drill sites.Consolidatedsedimentary rocksSome 110 million people in Africaoccupy areas of consolidatedsedimentary rocks which includelimestone and sandstone, and containwater in a mixture of circumstances. Itis more important to first understandthe general geology of an area to knowthe depth horizon at which water willbe located than to select a drilling siteon the basis of fractures. In this class ofrock types there are rocks and mixturesthat do not readily store groundwater,and in these cases more detailedinvestigations involving geophysics canassist.Unconsolidated sedimentsSome 60 million rural Africans liveon unconsolidated sediments wherewater will be located in layers of sandsor gravels. When unconsolidatedsediments cover a large area, it is3(Driscoll 1986).consistently easy to drill good sitesrepeatedly by drilling deep enoughinto the sand or gravel layer. Thereis also a useful range of sites basedon very localized sediments (in smallriver valleys, for example), particularlyin basement rock areas, as thesecan store appreciable amounts ofgroundwater from relatively shallowsediment layers.What iscurrent technologyoffering Africa?Borehole diameterThe DTH hammer has clearly carveda niche for itself in quarrying, andthere are numerous benefits for thistechnology in tapping groundwatersupplies. In quarrying, operators havelearned that - where fuel and capitalequipment are expensive to obtain andmaintain they can reduce operationalcosts by reducing the diameter oftheir blast holes and by improving theperformance of their explosive charges(Box 2).In setting a suitable bore diameter fora water well, the first principles of welldesign should be followed. Basically,adequate room is required to installthe water pump and to supply it witha flow that matches its maximumoutput. The India MKII technology,now in its third decade of operation,requires a minimum diameter of 4”(10.2 centimeters) for insertion. NewMKIII cylinders combined with theAfridev handpump will fit in boreholes6

Solutions for ReducingBorehole Costs in Rural AfricaBox 2. Borehole Efficiency and CostsA borehole is defined by its diameter and depth, calculated as volume. Thelarger the volume, the more the construction work. The surface area of a 4”diameter hole is close to half that of a 6” diameter hole. When multiplied byits depth, this will equate to a 4” hole being half the volume of a 6” hole.existing practice and would lead to thedisappearance of high-cost equipmentand high-value contracts. A realignmentof existing markets would ensue andequipment that is too large and costly tooperate would fall into disuse.Hard rock drilling spoil is cleared out by blowing compressed air up theborehole in the space between the drill pipe and drilled hole (annular area).The compressed air must travel above a certain speed (drillers refer to thisas ‘up-hole velocity’) to achieve sufficient lift of the spoil. This means thatthere is a direct ratio between the compressed air flow and the boreholediameter (a 6” hole requires twice the volume of compressed air than a 4”hole).The same ratio applies to the direct cost of constructing a 4” diameterhole which should be half the cost of a 6” diameter hole when the properselection of plant is made. This is because a 4” hole is half the work of a 6”hole. The drilled diameter has little effect on the volume of water availablefrom the borehole. It has been established that every time a boreholediameter is doubled, the available water inflow will increase only by 10percent. (Driscoll 1986).with a diameter of less than 4”, and it isfeasible to make installations for 3” (7.6-centimeter) holes. 3TraditionThe DTH hammer is still relatively newtechnology in a notoriously conservativeindustry. Without a DTH hammer,there are two options for penetratingrock. The first is to use a tricone bitwith heavy drill collars and torque.But to get enough weight of steel intoa hole in a short length, the optimumdiameter would have to be at least 6”(15.2 centimetres). Alternatively, a cabletool with a chisel and sinker bars couldbe used. This set up calls for a similarcritical mass and also leads to drill bitsof 6” or larger. Prior to the introductionof DTH technology, it was easier andcheaper to drill boreholes at 6” diameteror above than it was to drill smallerdiameters.Drilling regulations and standards,worldwide, are based on the applicationof these now superseded technologies.With DTH technology, however, it iseasier and cheaper to drill smallerdiameters. A DTH hammer will producethe lowest cost per meter in hard rockby a wide margin. An important provisois that the production rate has to bekept high to amortize the high capitalcosts of the equipment (Table 1).Vested interestsClearly, the adoption of alternativeborehole designs constructed withsmaller equipment departs fromWhile such a scenario would bebeneficial in terms of service coverage,it would clearly not go unopposed.Radical realignment of the businessenvironment in favor of smaller boreswould oblige established rig ownersand contractors to make a starkchoice – adapt to the change, orgo out of business. New investorswould be presented with considerableopportunities to win contracts, requiringa fraction of the resources currentlyneeded. With smaller bore diameters,the establishment of rural-based Africancontractors who could drill directly fortheir own communities would becomean attainable goal.The diameter of the DTH hammerdefines the drill-pipe diameter,compressor capacity, engine power,and rig size, weight and transportationmethod. Basically, the diameter ofthe borehole determines whether thecompressor is towed by a small pick-upor mounted on a four-wheel-drive truck,and whether the rig package costsUSD$60,000 or USD$150,000.By adopting new borehole designs thatspecify smaller holes, large equipmentis effectively made economicallyinefficient even though a small-diameterdrill pipe can still be used on a large rig.The increased use of commercial drillingcontractors would lead to construction7

Table 1: Representative borehole costs for conventional and reduced diameter drill rigsConventional Africa RigPurchaseCost US$PerboreholeReduced Diameter Africa RigPurchaseCost US$PerboreholeRig150,000Rig25,000Capital cost of a set ofborehole constructionequipmentMounting vehicleDrilling ToolsCompressor 750CFM x 15 barSupport Truck80,00070,00080,00060,000Drilling ToolsCompressor 250CFM x 10 barPick Up Truck15,00025,00030,000Pick Up Truck30,000Total470,000Total95,000Amortized 30 holes per year over5 years = 150 boreholesAmortized 30 holes per year over3,133 5 years = 150 boreholes633Surface Casing 6" 20m depthUS$20 per metre400Surface Casing 4" 20m depthUS$10 per metre200Cement - borehole seal & apron10 bags @ US$8 per bag80Cement - borehole seal & apron10 bags @ US$8 per bag80Sand & aggregate for apron120Sand & aggregate for apron120DrillingconsumablesFuel for compressor based on400 litres consumption@ 80 US cents per litre320Fuel for compressor based on200 litres consumption@ 80 US cents per litre160Drill bit wear & rig consumables250Drill bit wear & rig consumables125Hand PumpTotal600Hand Pump6001,770 Total1,285DrillerDrillerLabor costsDrivers x 2Asst Rig operators x 4Drivers x 1Asst Rig operators x 2Masons x 2Masons x 2600 400Equipment is attached to an officewith 50 staff - 2 rigs - 6 hand dugwell teams and 5 pumpmaintenance crew. Base has6 offices, store and maintenancefacilities + 5 support vehiclesPer annumEquipment is operated from a yardor a town plumbing shop - ownerlives in his compound and employs6 staff in his shop and storesPer annumOverheadsTotal spend on overheads300,000Total spend on overheads30,000Assume above attracts income of1 US$ million per annum.30 boreholes @ US$10,000 each= US$300,000 revenueAssume above attracts income ofUS$300,000 per annum.30 boreholes @ US$3,000 each= US$90,000 revenue30% overhead cost assigned to Rig100,00030% overhead cost assigned to Rig10,000Divided by production of30 boreholes3,333Divided by production of30 boreholes333TOTAL COST PER BOREHOLEUS$8,837TOTAL COST PER BOREHOLEUS$2,6528

Solutions for ReducingBorehole Costs in Rural Africaprograms that are more efficient andeffective than the direct labor activitiesof many governments. If boosted byrevision of drilling standards in favor ofsmaller bores, this outsourcing policycould also promote re-adjustment bythe drilling industry to demands ofthe restructured market. Commercialcontractors would then gradually phaseout oversized drilling rigs in favor ofsmaller and more profitable equipment.Borehole designin hard rockThe use of DTH hammer technologyhas made it easier to access watersupplies in hard rock where the costswere too prohibitive to allow extensivedrilling with older technologies. It wastherefore generally preferable to drill forwater in softer sediments and overlyingareas. However, a clean water supply inloose ground requires a well screen toact as a barrier to prevent soft soil fromcollapsing into the hole.reduce the available water flow andcreate a structure likely to be clogged bychemical or microbiological action overtime. Under such circumstances, neithermeasure is likely to improve the clarity ofthe original water.Holes drilled into the African basementor crystalline rock do not need liningto depth. In India, some three millionhandpump holes have been drilledinto hard rock, all of which are unlinedand unscreened. As well as doublingthe drilling cost, screening and gravelpacking block water from flowing freelyinto the hole.The very few rock holes that genuinelyrequire well screens and gravel packsto produce clean water can still usetelescoping materials to minimize drillingcosts.Soft sedimentsAn appreciable number of holes aredrilled in soft sediments using mudpumps and mud pits to circulate drillingfluids. The borehole volume dictates thesize of the mud pump needed, and theamount of water that must to be hauledand stored at the drill site. Reductionsin borehole diameter therefore lead tosavings, even when a DTH hammer isnot required.Holes in sediments usually require wellscreens (and possibly gravel packs)to create a filter, ensuring clean, clearwater in the well. Convention generallykeeps the construction diameter ofthe bore uniform from top to bottom.However, telescoping sizes opens up allsorts of possibilities for minimizing theIn some countries, old regulations areenshrined in convention, and nationalstandards insist on lining all boreholesto full depth. These regulations takeno account of the inherent strengthof underlying hard rock formationsthat DTH hammers are capable ofpenetrating. Having drilled through afissure crack and reached a supply of1,000 liters per hour of crystal clearwater, the driller is then obliged to shieldthe water flowing into the hole.A slotted pipe has to be first fitted in theabstraction zone, and then a curtain ofgravel placed between the fissure andthe pipe. Both these measures activelyA reduced-diameter drill rig in operation.9

Figures 5 & 6: Low cost borehole designs for crystalline rock and unconsolidated materialTOP SOILSANDSILTS & CLAYTYPICALLYDrilled 6" (150mm.)Dragbitwith 'Air, Form' or 'Mud'Flush4" (113 x 102 mm.) PVCcasingTypical water table risesabove water in fissuresSANDDrilled 6 1/2" (165mm.)Dragbit with 'Mud' flushonlySOFTWEATHEREDROCKCement / bentonitesealWATER TABLE4" (113X102mm.) PVCcasingGRANITEHand pump cylinder or4" submersible pumpSILTS & CLAY TYPICALLYHand pump cylinder or4" submersible pump.Cement / bentonite seal'crack' or'fissures'storing water113 x 63mm. PVC theadedadaptor2" (63 x 62mm.) well screenSlot size 0.5-1.0mm.Graded gravel packDrilled 100mm. Buttonbit3" DTH HAMMERSAND AQUIFER VERYFINE PARTICLESuse 0.7-1.5mm. gradedwashed sandto gravel pack for 0.5 slot size- use 1.0-2.0mm. gravel packfor 1.0 slot sizes113 x 63mm. PVC threadedadapterSump section 4" (113 x102mm.)PVC casing 3.6 meter long113 x 102mm. casing pointTypical depth 20-80 metersTypical depth 15-150 metersReduced diameter well screen for very fine sands requiring an even gravel packdiameters of drilled holes. Interestingly,telescoped designs would alsocontribute hugely to the enhancedperformance of bottom-supporteduPVC rising mains for deep-sethandpumps.Appropriate EquipmentBy defining the minimum requirementsof a community water supply basedon groundwater access rather than onthe equipment to be used, the localcontractor can then be left to determinehow the hole is constructed. Where thegroundwater is shallow and the waterlevel is relatively stable through dryseasons, a hand-dug well remains asound option.When groundwater is a little moredifficult to access, there are a numberof tripod-based drilling methods,largely hand operated, that producefully acceptable water supplies atvery modest costs up to depths of 20meters.As drilling gets deeper and involvesthe penetration of hard rock, largermachines are needed. These machinesshould be based on the boreholeconstruction required where the smallerthe borehole diameter, the lighterthe corresponding drilling rig (and itssupport equipment) can be.By definition, hard rock aquifersare fragile in terms of their rechargepotential. It is very easy to over pumpthem, as has happened in Indiaover the past two decades. Largediameter bore holes lend themselvesto power pumping, the abstractionof large volumes of water and heavydraw down – beyond the reachof most handpumps. Advocatingfor smaller diameter wells is alsomore environmentally friendly sincehandpumps do not damage aquifers.10

Solutions for ReducingBorehole Costs in Rural AfricaConclusionsThis analysis of borehole drillingtechniques suggests that the followingmeasures could make possible a hugeincrease in borehole construction, andrural water supply coverage throughoutAfrica.Relax the outdated nationalstandards that favorconservative borehole designsSmaller diameters holes shouldbe drilled to reduce the cost of theconstruction equipment and theinfrastructure needed to support them.Borehole designs need to embracevariations in geology, the occurrence ofgroundwater, and innovations in drillingtechnology.Develop an effective smallbusiness sector made up ofAfrican drilling contractors,based in rural areas, and spreadbetween the communities theyare required to serveThe alternative technology choice opensthe door to huge cost reductions inborehole drilling for water supplies, butthis technology needs skilful operationbased on both knowledge andexperience.An ideal world would see rurally basedsmall businesses operating drillingmachines for local community watersupplies. Such businesses would drillnew schemes, as well as have thecapacity to undertake well rehabilitation,pump improvements, and maintenanceduties.A portable drilling rig with DTH capacity.However, lack of specialized technicaland business skills hinders the abilityof local enterprise to undertake suchactivities. Seed schemes that couldprovide technical and business trainingto entrepreneurs, linked with credit forcapital equipment purchase, wouldimprove the success rate of such firms.Promote new, appropriatedrilling technologiesAcceptable borehole constructionsneed to be established and thenbroadened to the application of simplemachines capable of achieving thesestandards. Minimum quality controlthresholds for all new or modifiedborehole designs need to be developed.Provide continuity of work forlocal businessContractual frameworks that allow smallpracticing businesses some continuityof work should be created. Advantageswould include maximizing machineusage and availability within a fixedset of overheads, and increasing theconfidence levels of commercial lendinginstitutions in the local drilling industry.Such confidence would be increased bytraining and other methods designed tocontrol quality of drilling construction.11

References and further readingMacDonald, A. M., and J. Davies. 2000. A Brief Review of Groundwater for RuralWater Supply in Sub-Saharan Africa. Nottingham: British Geological Survey(Technical report WC/00/33).Driscoll, F. G. 1986. Groundwater and Wells. St Paul, Minnesota: JohnsonDivision.USCS Open File Report 97-470A, 1997UNTCD, Groundwater in North and West Africa, 1998UNTCD, Groundwater in Eastern, Central and Southern Africa, 1988Foster SSD, African groundwater development - the challenges forhydrogeological science, IAHS 144, 1984Guiraud R. L'hydrogeologie de l'Afrique, Journal of African Earth Sciences, 7 519-543, 1988.About the authorPeter Ball, PAT-Drill Europe Ltd.For over 30 years, Peter Ball has worked as a water-well drilling engineer forNGOs and international and national contractors throughout Africa. He hasspecialized in low-technology approaches to drilling water-supply boreholes,designing equipment and implementing construction programs that dramaticallyreduce technology levels and construction costs.November 2004The Rural Water Supply NetworkRWSN is a global knowledge network forpromoting sound practices in rural watersupply. RWSN grew out of the need tofocus greater attention on rural watersupply challenges and to encourage theexchange of experience and knowledge ofwhat works between the many public, NGOand private agencies involved in rural waterdevelopment.RWSN SecretariatSKAT Foundation, Vadianstrasse 42CH-9000 St. GallenSwitzerlandPhone: +41 71 288 5454Fax: +41 71 288 5455Email: rwsn@skat.chWebsite: www.rwsn.chACKNOWLEDGEMENTS:This field note was prepared by Peter Ball. Itwas peer reviewed by Jon Lane (IndependentConsultant), Rupert Talbot (Consultant for UNICEF),Bob Roche (The World Bank), Julian Jones andErich Baumann (both of RWSN/SKAT). JosephNarkevic (the Task Manager) and Piers Cross(WSP-Africa Team Leader) provided valuable ideasand guidance on the paper.Editors: Melanie Low and Toni Sittoni.Photo credits: Peter Ball, PAT-Drill Europe and EnterpriseworksDesign & layout: Kul Graphics Ltd.Publisher: WSP-Africa