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Case Study

BAM Ritchies, specialist blasting andgeotechnical contractors, have beeninvolved throughout 2009 and into 2010

on two major overseas contracts managingdrilling, blasting and crushing operations —the rehabilitation of the TANZAM Highway inTanzania and the construction of a fisheriesharbour at Dikkowita, Sri Lanka.

RReehhaabbiilliittaattiioonn ooff TTAANNZZAAMMHHiigghhwwaayy,, TTaannzzaanniiaaThe €75 million contract to rehabilitate andupgrade approximately 150km of the existingTANZAM Highway from Iyovi to the foot ofKitonga Gorge and from the top of KitongaGorge to Iringa is being undertaken by BAMInternational and Danish partner Per Aarsleff.The 7km steep Kitonga Gorge section is notincluded in the project as it was previouslyreconstructed in recent years.The TANZAM Highway is the main transport

route from one of Africa’s largest ports, DarEs Salaam, leading into Central Africa, mainlyZambia and the Congo. The start of theproject road is approximately 6h drive west ofDar Es Salaam.Works include pavement recycling,

mechanical stabilization, strengthening,shoulder pavement construction and trafficsafety improvements. The road section of thisproject was initially constructed in the 1970swith an asphalt concrete surface supportedby either a cement-stabilized or crushedstone base and natural material sub-base.For the aggregates supply element, BAM

Ritchies carried out pre-tender and post-award site investigations of potential quarrysites along the 150km length of the plannedproject section. It was the planned intentionto develop two quarries to provide allaggregates for the project, one east and onewest of Kitonga Gorge to negate therequirement to haul materials over the gorge.

The consequential test results confirmedthat the available rock was a granite typematerial that is found throughout Africa.Quantities and specifications of quarried

rock required for the project were:• Basecourse:

Crushed rock class CRR with gradingCML1.7 0-40mm – 750,000 tonnes

• Aggregates for asphalt:0-4mm grading – 125,000 tonnes4-9mm grading – 121,000 tonnes9-15mm grading – 22,000 tonnes.

Thus, a total of over 1,000,000 tonnes ofproduct was required within a total crushingprogramme period of 24 months. The currentcrushing target is 50,000 tonnes of product permonth.BAM Ritchies investigated available

crushing plant to suit the specific contractneeds and investment restraints. The following mobile equipment was sourced,purchased and shipped from the UK to �

Quarry Operations in Tanzania and Sri Lankaby Alex Tiernan, contracts manager overseas operations, BAM Ritchies

Process plant layout

40 www.Agg-Net.com August 2010

Dar Es Salaam: • Primary crusher x 2:

Pegson 100 x 800 single-toggle jaw • Secondary crusher:

Pegson 1300 Maxtrak cone• Tertiary crusher:

Pegson 1000 Maxtrak cone• Triple-deck screen:

Powerscreen Chieftain 2100• Double-deck screen:

Powerscreen Warrior 1400.An Ingersoll Rand ECM drill rig and

compressor was also transferred from aprevious BAM International contract in Ghana,to supplement a similar drill rig andcompressor supplied by BAM Ritchies, alongwith all drill rods, bits and consumables,through the company’s Glasgow office. Drillingis carried out using 23⁄8in reg. rods with a down-the-hole hammer fitted with 115mm COP44button bits.BAM Ritchies are also carrying out all

shotfiring on the project with all explosives

stored in a purpose-built licensed sitemagazine. In the first 11 months of thecontract some 1,900 holes were drilled: a totalof 24,582m with an average depth of 13m,yielding 568,680 tonnes of blasted rock.Initially, a quarry was opened up at

Mazombe to service material requirements forthe section of the works west of the gorge,followed by development of the second quarryat Ilindi at the eastern side of the gorge. Therock from Mazombe was processed within thequarry while at Ilindi the rock is being primarycrushed at the quarry and transported to thenew road alignment where it is stockpiledready for the existing secondary plant fromMazombe, which was moved down oncompletion of the western section of theroad in spring 2010. Rock from Ilindi will beused primarily for basecourse.All asphalt for the project will be

manufactured at Mazombe Quarry andsufficient stockpiles of crushed rock will be left for the tertiary crusher to produce

the required aggregates.To date some 350,000 tonnes have been put

through the primary crusher at Mazombeproducing over 205,000 tonnes of basecourseand 95,000 tonnes of asphalt and concreteaggregates.The project is forging ahead with some

35km out of 150km finished road completedto date. Planned completion of the project isearly summer 2011.

DDiikkkkoowwiittaa FFiisshheerriieess HHaarrbboouurr,,SSrrii LLaannkkaaBAM Ritchies is working with Dutch sistercompany BAM International on a design andconstruct contract for the Dikkowita FisheryHarbour Project in Sri Lanka. The new facilitywill be the main fisheries port on the westcoast of Sri Lanka and is situated some10km north of Colombo.The new harbour will replace inadequate

existing berthing facilities at various locations,allow for future fishing fleet expansion andprovide proper facilities for both localconsumption as well as export.The project will provide:• Two breakwaters forming the seaside

part of the harbour• Quay walls at the land side of the

harbour• Piers for off-loading ships• Lay-by piers for ships• Wave-energy dissipation beach• Land reclamation with slipway within

the harbour plot• Landfill at the building area• Processing and service buildings• Infrastructure for the works• Dredging of the harbour to the required

depths• Drill and blast operations to the harbour

mouth• Roads/pavement with storm water

drainage• Access road with bridge.BAM Ritchies are particularly involved in

managing the procurement and delivery to siteof suitable rock to form the breakwater and

Basecourse production

TANZAM Highway construction

Primary crushing at the quarry face

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fill areas, and the drill and blast of theharbour entrance.Their involvement also included supervision

of a detailed offshore and onshore siteinvestigation prior to the main workscommencing.An existing quarry was located and

materials were tested in both Sri Lanka andthe UK to confirm compliance with applicablestandards. This quarry is situated some

50km from the project and was in the courseof development to provide aggregates for localcontractors.Under BAM Ritchies supervision, the quarry

has been totally redeveloped to meet theproject’s specification and programmedemands.The requirements for the harbour call for

a complete range of materials to be extracted,ranging from basic core material to heavy

armour blocks. There is no requirement forany crushing of quarry materials since allconcrete aggregates for the project are beingprovided by other local suppliers.The contract requires the supply of the

following quantities of rock:• Core layer

0.5–500kg – 136,836 tonnes• Filter layer

60–300kg – 46,200 tonnes �

Dikkowita Fisheries Harbour planned layout

Sizing armour stone at the quarry

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• Armour stone200–300kg – 2,640 tonnes

• Armour stone300–1,000kg – 17,460 tonnes

• Armour stone 1,000–3,0000kg – 31,500 tonnesTotal rock supply – 234,636 tonnes

Until a suitable track drill could bepurchased and delivered, the quarry continuedto utilize hand drills producing an impressive

average of 1,400 tonnes per day. BAM Ritchiessupervized daily blasting and segregation ofblasted materials. Examples of key stones andthe use of measuring devices ensured that thespecified grading was maintained. Separatestockpiles of graded rock are kept at thequarry and delivered to schedule daily.The quarry has recently taken delivery of a

new air track drill and production has beenincreased to 2,000 tonnes per day.

The main difficulty experienced on theproject is transport. Currently, the quarry hasover 100 trucks delivering rock to site on adaily basis.Although the journey to site is only 50km,

it is arduous, utilizing a road system hardlydesigned or adequate for such deliveries. One-way trips can take up to 2h to negotiate andthe quarry always has a few trucks in reserveto cope with the expected breakdowns. Around50% of the total rock requirement has alreadybeen supplied.So far, the core fingers of the breakwater

have been constructed and work now involvesthe placing of site-manufactured concrete x-blocks and armour stone.BAM Ritchies are currently mobilizing

supervisory staff to manage the drill and blastoperation to widen and deepen the naturalentrance to the harbour formed betweenthe existing natural reefs. A rotation drill headwith associated drill consumables have beensent to Sri Lanka from Scotland to be fitted onto a local drill rig, which will drill from a locallymanufactured platform fitted to a BAMInternational barge, normally being used onthe site dredging operations.All works are ontarget to be completed early in 2011.Contracts manager Alex Tiernan

commented: ‘These two contractsdemonstrate the complimentary skills ofBAM International and BAM Ritchies, whenworking together overseas on schemes withaggregate and armour stone requirements.They extend the notable track record of jointproject delivery in a variety of developingcountries for different types of infrastructureschemes.’ QM

Separation of blasted rock into graded stockpiles at toe of quarry face

Placing x-blocks and armour stone on core material

Case Study