Greenhouses
Planning a Greenhouse Project from an Irrigation Point of View by Jerry Austen - Netafim South Africa
The installation of a greenhouse project typically takes place in a confined area , in comparison to open field projects on a farm with many people from several disciplines ; all coordinated by the Project Manager , who would usually be the grower himself . This paper looks at aspects related to the irrigation design that need to be considered long before the project gets underway .
The project life cycle
Like any project , the life-cycle of a greenhouse project goes through the following overlapping phases :
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Definition – This would include the preliminary irrigation design .
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Planning – This would include the actual irrigation design .
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Implementation – Including procurement , construction and installation .
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Close-out – Including commissioning of the project .
See Figure 1
The costs increase rapidly as the project progresses through the first stages , peak during implementation and tail-off in the close-out . Changes that occur during the project for whatever reason , have an effect that becomes more pronounced the later that they occur into the project .
To this extent , the later into the project , the less flexibility there is to make a change . See Figure 2 . Any change during a project
involves an interaction between the following three factors . See Figure 3
XX Cost
XX Quality
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Time
For instance , if a certain task ’ s completion date needed to be brought forward ( time ), it could only be done by increasing resources ( cost ) or reducing quality . The time cannot be reduced by keeping costs and quality as they were .
The later the changes , the worse the effect on one or more of cost , quality and time . The following looks at the feasibility of changes to the irrigation design during each of these phases .
Changes in irrigation design – Definition phase
The preliminary irrigation design takes place during this definition phase . Changes are very feasible . This phase is earmarked for changes and this is the phase to get a reasonably clear idea of what one wants .
Changes in irrigation design – Planning phase
This is the phase where the irrigation design is formulated . Materials will be procured against this design . Changes are still reasonably feasible during the planning phase .
Changes in irrigation design – Implementation phase
Procurement of materials occurs during this phase . Once procurement has begun , changes are more difficult . Irrigation equipment for instance is often only manufactured-to-order . Construction and installation occurs during this phase . Changes now begin to have a more severe effect with increased costs , time delays or a reduction in quality .
This is the phase in irrigation systems where most changes through inadequate planning come to light .
Changes in irrigation design – Close-out
This is when commissioning takes place and where changes are for all intents and purposes not feasible .
The Project Manager and the integration of the irrigation with the rest of the project
The irrigation part of the project cannot be viewed in isolation at any time during the project life-cycle . The irrigation involves the interaction of the following aspects and individual specialist personnel , which must be catered for , planned and integrated from
Figure 1 . The project life cycle and costs Figure 2 . The ability / flexibility to make changes during a project Figure 3 . Cost-quality-time triangle
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SABI | AUGUST / SEPTEMBER 2016