CONSTRUCTION OF THE VISITORS CENTRE AT THE ISIMBA HYDROPOWER PLANT
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1.1 Introduction Isimba hydropower Plant Visitors Center has been developed under a Design and build contract with China International Water and Electricity Corporation as one of the supporting facilities to be used by the public and staff of the hydropower plant. The 183MW Isimba hydropower plant, associated Transmission lines and Substations have been developed along the Victoria Nile so as to generate and increase the amount of hydropower electricity on to the National Grid. On that note, a number of other supporting building and infrastructure facilities have been developed. However the Visitors Centre and the Isimba Bridge were one of the snags listed for the Isimba HPP project. Hence it was identified as a missing item during the snagging period after the commissioning of the Isimba HPP/ practical completion of the project. Its design development and construction have all been done within the defects liability period (DLP) of two years. The project cost for Isimba HPP inclusive of the Visitors Center and other support facilities is five hundred fifty four thousand, seven hundred million United States dollars ($ 554,700,000). And the VC itself was estimated at a cost of four hundred eighty thousand United States Dollars ($ 480,000). This project received debt financing from the China Export Import Bank (EXIM) and was approved by the Parliament of Uganda. Specialists involved in the design and design review of the visitor’s center include: Creations consults who undertook the architectural design and Mwemat Ltd development and Engineering consultants undertook the structural design and IMK engineering Ltd under took the designs for both electrical and mechanical works. The Visitors Centre is build in the Isimba HPP site and it is located in close vicinity of the Power house, the left embankment dam, the Switch yard, proposed shopping center and the proposed canteen. The key design features of the structure included: functionality, comfort to enhance efficiency, convenience to the users and durability and aesthetics. 1.2 Geotechnical Investigations Teclab Ltd undertook and completed a soil investigation study for the Visitors Centre prior to its construction. The soil investigations included exploratory trial pit excavations, profiling subsoil conditions, sampling, insitu testing (Dynamic cone penetrometer-DCP) test, and laboratory testing in accordance with the agreed scope of work. The geotechnical investigations were carried out to assess the characteristics of the subsurface ground in respect: Characterization of the nature of the shallow geology and ground water to a depth of 3.0m from the ground surface level. Confirmation of the general physical characteristics of rocks (lithology) in the site area and thickness of the subsurface layers Determination of physical and geotechnical properties of soils relevant to geotechnical design of the structure’s foundation. Investigation portrayed that the site was covered by a layer made up ground and a mantle of residual soils, which were generally uniform in composition comprising of firm greyish black sandy SILTS of low plasticity with visible vegetation roots up to a depth of 1.4m which form the superficial natural layer. Ground water was not found in any of the trial pits within the investigated depth. 1.3 Design Review The design reviews are undertaken after approval of the designs to enable execution of work. And on that note a review of structural drawing was carried out right before the start of the construction works of the structure. . As an inspector of works and supervising engineering personnel of the Visitors Centre, I was involved in the design reviews of both the structural and architectural designs. Electrical and mechanical designs were reviewed by Electromechanical Engineers. Design review reports were prepared and submitted to the contractor for later action. The activities that were carried out during the design review stage included: Site visits and familiarization of the project area Desk review of designs drawings Review of industry standards in relation to the designs Analysis of the designs in relation to standard and codes Preparation of subsequent reports 1.4 Quality Management Good work without compromise always produces quality. Therefore having this quality in place throughout a project life-cycle creates the need for Quality management. And to simplify the process of quality management, it is broken down into Quality Assurance (QA) and Quality Control (QC). Design reviews can also be referred to as design Audits. They play an important role in the quality production of construction projects. The conduct of design reviews should be compulsory as part of the design controls, when developing products in the construction industry or any other field. A number of factors were put in place to ensure that all quality measures conformed to the set or prescribed standards. The factors included Project documentation, design reviews, Team work, Inspection and supervision, material investigations and testing. Design reviews for the VC designs were done before and during the early stages of the construction process. It involved reviews of architectural, Electrical and Mechanical drawings. There were a number of improvements to the designs and it also improved the quality of the building structure and its support facilities such as the road yet to be constructed, walk way and the parking area. Some omissions were identified and these too were catered for in the drawings. For example the Residual Current Devise was identified as a missing item in the Electrical Design. There was major improvement to the architectural finishes such as the access door structures, inclusion of expansion joints in the floor tiles etc. 1.5 Construction Supervision This demonstrates my roll as the OE inspector of works where I undertook the responsibility of supervision and inspection of the construction process, installation of electrical and mechanical installations during the construction of the Visitors Centre. The general and detailed construction procedures and also the variety of tests that were done during the progress of the project works were checked for conformity with the specified standards and codes referenced in the contract documents such as the bills of Quantities, specifications, design drawings, national building codes, BS standards among others. I was also involved in the selection and approval of material samples that were used on the structure during the construction phase. The scope of work involved different stages of the construction process. The scope included: preliminaries under which site clearance, hoarding, removal of surface vegetation and top soil, construction of temporary structures etc are involved. The next stage of work was the substructure which involved the construction of the foundation. Then followed the super structure and the roofing stage. Finishing works such as plastering and painting, electrical, and mechanical installations and fittings and fixtures followed the completion of the super structure. And finally external works such as construction of the septic tank and soak pit, man holes, walkways, drainage channels etc. 1.6 Cross Cutting Issues Cross cutting Issues affect the planning and implementation stages of construction projects but which have not been given sufficient attention. To Implement a project successfully, in time and within budget, there is need to incorporate these cross cutting issues in all stages of the project process. International agencies such as WASH advise to include cross cutting issues in all stages of project processes, but this has not always been the case. Some of the cross-cutting elements that go hand in hand with construction works include; Occupational Health and Safety (OHS), Gender Mainstreaming, Community Empowerment, COVID 19 and Social Accountability. Occupational Health and Safety Act 2006 in relation to work, is the physical and mental elements affecting health which are indirectly or directly related to safety and hygiene at work in addition to the absence of diseases and infirmity. Safety on the other hand is the condition of being protected from or unlikely to cause danger, risk, or injury. 1.7 Lessons Learnt, Conclusions And Recommendations Isimba HPP is one of those major projects in the Ministry of Energy and Mineral Resources and because of its uniqness and complexity, there has been so many lessons and challenges involved with it. As an inspector for all civil works at Isimba HPP, I have generally encountered very many lessons and challenges that have enabled me build confidence in my career by being able to have solutions to problems particularly in the civil engineering field. My full participation of ensuring quality during the construction of the VC has also helped me to learnt more in the building and construction field. I learnt that the health and safety of workers should not be taken for granted. Or else if a pandemic attacks workers who are familiar with the work, it will then cause delays in the project implementation. Hazards need to be identified and eliminated because if a worker gets injured on site, it becomes a cost implication to the contractor. Therefore it is important to ensure that the workers practice good health and safety measures. Another lesson learnt was the importance of maintaining site records and also to keep documents of a project because at one time they may be needed as references during audits and during interim payments. I also learnt that as an inspector of works, the quality of the works were dependent on my decisions at all times. Therefore I ensured that all laboratory tests were done and I compared the results with set standards. I learnt that a good work plan for site works is key in the timely project delivery. And the site supervisor on the VC always presented a weekly work plan dependent on the project’s schedule and this enabled the timely construction of the VC. I got learnt that having a site team that collaborated well with each other also eliminated prolonged site disputes that could affect the progress of the works. I learnt that geotechnical investigations for large projects is important. This helps to determine the unforeseen ground conditions and therefore respond otherwise with treatment measures just incase of undesirable conditions so that there will be no risks of proposed foundations after construction. 7.2 Conclusions Much as one could have a good project team and all quality measures in place during construction of a structure, inadequate soil investigations will result in foundation defects. And lack of appropriate design reviews before and during the early stages of construction can result in structural defects and errors on building projects. Therefore in my conclusion, I strongly advise all stakeholders of construction projects to ensure adequate soil investigations and design reviews for building sites to enable them achieve their intended purpose and design service life. 7.3 Recommendations Recently a number of building structures are collapsing in the city and surrounding towns and as a result, causing temporary or permanent body injuries to persons, deaths and loss of property. On that note, my advise to our building regulatory authorities is to ensure and monitor that developers comply to the set standards that should be adhered to during the design and construction stages of building structures. Lack of such restrictions is a result of fatal problems caused by failure to adhere to principles.