Plant supply contracts
Many civil engineering projects incorporate electrical or mechanical plant which has to be ordered before construction commences because of the time required to manufacture the plant. Details and dimensions of the plant will be required to permit design of structures to proceed. Thus the employer has to let contracts for the supply of such plant in time for delivery of the plant to occur when the construction needs to incorporate it. Figure 5.1 shows a plan drawn up to co-ordinate plant deliveries for construction of a water treatment works. A plan of this kind is needed for many types of project.
However, because the employer orders the plant he becomes liable for any delay caused to the civil contractor if he does not place an order in time, or the plant supplier defaults on his promised delivery period. The resulting delay claim from the civil contractor can be expensive, hence it is prudent for the employer to allow a safety margin on plant delivery times. Thus the delivery times for plant quoted in the construction contract are put somewhat later than suppliers quoted delivery times to give a margin for possible delay. Although this may result in plant being ready before the construction contractor needs it, this is the best policy to follow. It is often possible to persuade a supplier to hold plant in store until needed, and the extra charge he may make for this or
the cost of getting the construction contractor to temporarily store some plant on site will be less than the cost of delaying construction.
An alternative is for the employer to pass to the construction contractor the responsibility for arranging delivery of plant as he needs it. This was done on the Mangla dam project in Pakistan where eight major suppliers for hydroelectric plant, gates, valves and other large equipment were involved. The civil contractor was required to take over the plant supply contracts and arrange delivery to suit his construction programme, after such plant had been tested to the satisfaction of the employer. This kind of approach, however, is only practicable where the project is so large, as at Mangla, that construction takes several years to complete.
Site preparation contracts
An employer may also let a separate civil engineering contract for sitepreparation, which covers building of access roads, bulk excavation, and providing electrical, water, and sewerage services to the site. Housing for site personnel may also be included. This contract can be let while detailed design of the project is still ongoing, and can therefore contribute to early project completion.
Other advantages are that some excavation can be left open for the civil works tenderers to view, so minimizing the risk of claims for unforeseen ground conditions, and arrangements can be made for temporary storage of pipes and valves, etc. the employer orders which the main contractor has to incorporate in the works. However a site contract must be completed before the main civil engineering contract is let.
Co-ordination requirements
When separate plant supply contracts are let, the main civil contract must include all details of what the civil contractor must do in connection with such plant. Among the matters to be specified and allowed for in the bill of quantities are the following:
Items requiring the civil contractor to take delivery of plant, offload, store,
protect, and insure it.
Items requiring the contractor to check deliveries of plant as invoiced by the supplier, inspecting items for any damage, and drawing the attention of the employers engineer to any such, and to missing items.
Where the plant supplier is to erect his plant, the main civil contract must state what services the civil contractor is to provide the supplier with, such as access, scaffolding, lifting gear, power and lighting, water, use of the contractors canteen and toilets, etc.
Where pipes or other plant items have to be built in the civil works, the contract must make clear whether such items have to be built in as the work proceeds or whether a hole can be left for a pipe to be built in after.
The contract drawings should show how the latter has to be done, and who is to be responsible for positioning any such item correctly.
The interface between all separate contracts has to be carefully checked to ensure that all matters to be done by the plant supplier or civil contractor are properly covered and none missed out. The principal responsibility for this will lie upon the employers engineer in charge of design and the drawing up of contracts. On a large scheme where several teams of engineers work on different parts of the design, checking that the interface between their separate parts match, is equally important.