Construction of Irrigation Schemes

1 Irrigation ManualModule 13 Construction of Irrigation SchemesDeveloped byAndreas P. SAVVAandKaren FRENKENW ater Resources Development and management OfficersFAO Sub-Regional Office for East and Southern AfricaIn collaboration withLee TIRIVAMWE, National Irrigation Engineer, ZimbabweVictor MTHAMO, Irrigation Engineer ConsultantSimon MADYIWA, Irrigation Engineer ConsultantHarare, 2001 Irrigation manualii Module 13 Module 13 iiiContentsList of figuresvList of tablesviList of Overall project Site Staff Materials Equipment Maximizing Settlement of disputes83. PROGRAMMING Construction Equipment Performance of some Front-end loader with Labour Labour for Labour and equipment for the Construction of concrete-lined Labour and equipment for the Construction of Use of bar chart for programming Construction activities174. TYPES AND USE OF Construction Important properties of Concrete Concrete mixtures and Transporting, placing, compacting and curing Steel Mass Gabions and Reno Bricks, cement and concrete Pipes and Types of pipes and Packing, transporting, storing and handling of pipes and fittings25 Irrigation manualiv Module OF Setting out Canal Placing and curing OF Trenching and pipe Pipe Thrust Pressure Initial Pegging final levels35 REFERENCES37 List of employer-contractor roles and presentation of employer-contractor lines of programme progress and resource charts or S cur example of a bar of different types of equipment used in Construction scrapers at work, CAT621G and hydraulic motorized grader, CAT120H1210.

2 Wheel loader at work, CAT928G1211. Articulated truck or tipper, CAT730 1312. Hourly production versus cycle time performance cur ves for a wheel tractor-scraper1313. Typical performance cur ves for a wheel tractor-scraper1414. An example of a gabion basket structure2415. An example of how AC pipes are stacked2516. A traveler for setting out canals2717. Setting out a canal using a traveler2718. Metal template for shaping canals2819. Trapezoidal canal former2920. Final cross-section and initial embankment of a canal3021. The transport programmes for the cut and fill process during canal finalization3122. Timber shutter frame for concrete slab casting3223. uPVC pipe jointing technique3424. Indication of cut and fill in the field35 Module 13 vList of of responsibilities between contractor and of contract manager and their site quantities for of manual labour in chart for the Construction of a surface Irrigation scheme for concrete and mortar mixes by mix proportions by volume batching for different concrete of the various concrete grades22vi Module 13 List of abbreviationsACAsbestos Cementc/w ratiocement/ water ratioHPCH eight of Point of CollimationPEPolyethyleneSABSS outh African Bureau of StandardsuPVCunplasticized Polyvinyl ChlorideZGCCZ imbabwe General Conditions of ContractModule 13 viiIrrigation manualviii Module 13 Module 13 1 Irrigation projects, like any other project, have a promoterwho is responsible for the provision of funds with which toexecute it.

3 This could be a government, a donor, or in somecases the users themselves, such as a group of farmers oreven an individual farmer. The promoter appoints anengineer to assume the overall engineering responsibilityfor implementing the project on their behalf. The responsibility of the engineer starts with the design ofthe project and extends through the super vision of itsconstruction. The engineer participates in the preparationof the feasibility report of the project, which shows thescope of work and estimated project costs. Once thepromoter and farmers or end users accept the project, theengineer can proceed to prepare tender documents for theexecution of the works (see Module 12). Tenderers submitoffers, showing the cost of and time schedule for theconstruction. The engineer will then make a comparativeanalysis of the tenders and make recommendations to thepromoter.

4 The promoter, also called the client, will thenaccept one of the tenders and sign a contract with theselected tenderer. At this point, the tenderer becomes thecontractor and the client or promoter becomes theemployer of that contractor. Construction activities projects are capital projects that need to followgeneral contract procedures during their the centre of these procedures is the employer-engineer-contractor relationship. This relationship defines thecontract management between the parties involved, onewhich is bound by the general conditions of contract (seeModule 12). In order to accomplish the job as per thecontract, the contractor needs an effective projectmanagement system at the organizational level as well as atthe operational level on the site ( chapter 2). Timescheduling or programming of activities for constructionshows how the works should be organized and whatresources mobilized in order to meet the targetedobjectives in the implementation of the project (Chapter3).

5 Finally, this module will look at the way some of themost common Construction activities are actually carriedout (Chapters 4-7). In reading these last four chapters, thereader will need to refer to the modules dealing with thedesign of surface, sprinkler and localized Irrigation systems(Modules 7, 8 and 9). chapter 1 IntroductionIrrigation manual2 Module 13 Contract management comprises the management of theconstruction site, its activities and its resources under theagreed conditions of contract. The Construction of an Irrigation scheme should be viewedas a project in itself. A project is defined as a set of activitiesthat are linked together over a period of time and arecarried out to produce specific goals. Project managementis the planning and the control of the project activities toensure that the goals are achieved in time and within thebudget. management includes the following three processes:1.

6 Organization: refers to roles, responsibilities andreporting structure2. Planning: refers to resource planning and activityplanning3. Control: refers to control meetings and control pointsThese three processes are a necessar y part of projectimplementation. They apply to Irrigation projects as muchas they apply to any other civil engineering project and areimportant to both the employer and the contractor. There are two levels of project management : Ythe organizational level, usually at the head office,involving the contractor and the engineer, who isappointed by the employerYthe operational level on the site, involving the con-tractor s site agent, also called site manager, and theengineer s representative at the site, also called residentengineerFrom the contractor s point of view, the contract managerand the site agent are responsible for the management ofthe contract.

7 From the employer s point of view, theengineers are responsible for managing the , the management of the contract is a jointresponsibility of the two parties at both projectmanagement Overall project managementThe contractor has to put in place an effective projectmanagement team in order to execute the project on timeand within the budget. It is therefore important at this stageto define the relationship between the employer, theengineer and the contractor so as to understand how theconstruction project has to be managed (Figure 1). Theroles and responsibilities of these three parties involvedshould be well defined and spelt out in the generalconditions of contract. They may var y from countr y tocountr y but they largely address the same issues. The following definitions help to clarify the role of thedifferent actors in managing a contract:YContract: A contract is a legally binding agreemententered into between the employer and the contractorfor the execution of the works desired by the is also an expression of the willingness of theemployer to pay the contractor and of the contractor todo the work as per the documents: Contract documents consistof the following documents: conditions of the contract,specifications, drawings, priced bill of quantities,schedule of timing of works, schedule of rates andprices, the tender and the contract agreement.

8 Signingof the contract agreement is an endorsement that bothparties are happy with the contents of the : The employer, also called the promoter orinitiator of the project, is responsible for providing thefunds for the : The engineer is the person appointed bythe employer and notified in writing to the contractoras having the overall engineering responsibility for thedesign and super vision of the Construction of engineer: A resident engineer is theengineer s representative on the site of the works. Theresident engineer discharges the functions of theengineer upon delegation of such powers and authorityby the engineer in writing to the contractor. Other wise,the duties of the resident engineer are to watch,super vise the works, test and examine materials to beused and the workmanship in connection with theworks. As shown in Figure 2, the engineer may appointpersons to assist the resident engineer.

9 The contractorshould be notified of such persons and their 13 3 chapter 2 Contract managementThey do not have power to issue instructions to : The contractor is a company, firm orindividual who undertakes the execution of the the contractor s point of view, the contractmanager and the site agent are responsible for themanagement of the contract. The site agent is directlyresponsible for managing the contract on site. Fromthe employer s point of view, the engineer isresponsible for managing the contract. Therefore, themanagement of the contract is a joint responsibility ofthe two parties at both management levels. YProject or contract manager: The project manager,also known/referred to as the contract manager, iseffectively responsible for contract management fromthe contractor s point of view and provides back-upser vices to the site agent.

10 If the employer so wishes,they can also have a project manager. YSite manager or site agent: The site manager, alsoknown as the site agent, is the representative of thecontractor on the site of the works. The agent is a legalrequirement for most contracts. They receiveinstructions from the engineer, which become bindingon the contractor. As far as the contractor is concernedIrrigation manual4 Module 13 Figure 1 Overall employer-contractor roles and responsibilitiesthe agent is primarily responsible for the successfulcompletion of the works with due regard to time,workmanship, safety and the cost. The site agent isresponsible for a whole host of activities, chief amongwhich are: planning, organizing, administering,engineering, personnel and plant management , andfinancial control. Site management is in fact themanagement of resources. The resources are known asthe 5 M s, being: Methods, Men, Machines, Materialsand Money.