The climatic, hydrological and geotechnical characteristics of the Niger Delta makes infrastructural development relatively difficult and expensive and it require more technical ingenuity and financial commitment than other parts of the country. All the same, the cost of collapse structure and its associated impact cannot be quantified more so, construction is dangerous work and accounts for over one-firth of all occupational fatalities (Center for the protection of worker’s right, 1998) hence there is need for quality and productivity improvement of construction in the region.
The Niger Delta region is mostly a flat swampy basin made up of vast plain, built up by accumulation of weak and highly compressible alluvial sedimentary deposits from the Niger and Benue rivers. The region is exposed to flood crisis crossed by a myriad of rivers – logged depressions where rainfall and surface water flow can hardly be drained by gravity, also the sea scours, floods and breaks on the river banks cause severe coastal erosion.
It can also be deduced that flood, erosion and excess water related constraints are major problems that hinder construction work. There is also erratic soil condition with swelling and shrinkage problems and excessive settlement of the shikoko soil –spongy fibrous deposits in the region thereby affecting the shear strength of the subsoil. The shear strength of a soil could be said to be the ultimate or maximum shear stress the soil can withstand and it is the most important aspect of geotechnical engineering because structures and slopes must be stable and secure against total collapse when subjected to maximum anticipated load. With recession of flood, soil and river banks collapse is a common feature. These and other physical constraints makes the engineer to be faced with much greater challenge than engineers in other parts of the country, therefore the ecological and physical constraints dictates the need for much more technical ingenuity and care in the various phases of the construction.
Lack of proper planning has often led to delays that lead to increased cost of construction and incessant demands by host community. The peculiar terrain and prohibitive cost of construction in the region necessitates the need for thorough and adequate planning. The planning process involves data collection, analysis of field measurement, contingency plan for host community, inspections and monitoring control plans. For each category and phase of operation, the quality plan should be able to address these questions?
- Who will be responsible for QC during the operation?
- What will that person do to ensure contract compliance?
- Where will these activities be performed?
- When will these activities be performed?
- How will inspections be performed?
Experience has shown that early construction distress manifestations (e.g. cracks) are mainly due to the use of substandard materials or poor construction. This is due to lack of proper quality control/monitoring and quality assurance/supervision during construction. Quality control and quality assurance programs are normally designed and performed to ensure adequate quality of construction as the work progresses, and also to see that the work is performed strictly in accordance with the approved drawings and specifications.
The geotechnical and hydrological characteristics of the construction site also dictates the necessity for effective measures of soil and other construction material treatment, and prevention of water on or into the foundation. Practical measures need to be used to improve the engineering characteristics of highly compressible silty clay soil likely to be encountered. In addition to adequate compaction, stabilization with cement or lime is imperative for the foundation base.
For soil in the mangrove swamps, preloading with free draining materials such as sand on the swampy soil will take care of the excessive settlement problems of the soil and increase the strength and resistance to shear and compression. Also the use of heavy duty equipment (e.g. pay-loader, crane, etc), will help compact thus, improve the soil.
Heavy rainfall and river discharges during the wet season, combined with the flat terrain and poorly drained soil and high water table, provision of adequate drainage facilities to convey excess water and subsurface water across the site is a must. Such drainage facilities such as drainage channel are very necessary and should be provided to prevent flooding with adequate drainage, proper treatment of materials, inspection, sampling, testing and effective monitoring should be able to address or minimize the challenges of construction.
Worker’s attitude and awareness, product/supply problems, multitude of parties involved in construction, host community, lack of incentive and poor remuneration are all barriers to quality improvement and implementation in construction and these should be properly taken into consideration before the commencement of work. All materials and supplies should be accompanied with manufacturer’s certificate and manual.
Lastly, safety is an important aspect of quality management, in-fact it is interwoven and safety and quality prequalification in the bidding process can help check this and would also help publicize the concept.