Soon after completing the multi-million Solar Photovoltaic and Gate Electrification System to cut down on the carbon emission at Moi International Airport, KAA embarked on another multi-billion refurbishment project to improve and uplift the standards at the airport. The Kenya Engineer team sat down with Eng. Samuel Mochache, the projects manager to give an insight….

Eng. Mochache is a civil Engineer by training and a pavements specialists involved mainly in design and construction supervision of pavements. Currently his line of work is mainly focused on aircraft pavements at airport facilities under KAA.

Specific roles at KAA

My position within the organization is Manager for Engineering projects with the Projects and Engineering Services department. Specifically my roles are to discharge the roles of a project manager for major projects, mostly donor funded projects and this includes procurement of consultants as well as contractors then to the next phase of construction supervision and contract administration of the major infrastructure that we have at the authority.

Let us discuss the pavement rehabilitation project at Moi International Airport

For starters the scope; the project involves pavement rehabilitation, it also has a component of air-ground lighting system for navigation aide. The other component of the project is drainage. You will know that drainage is a major factor to consider when installing pavements. There is also the component of remediation of what was thought to be sink holes in the air side which our ground investigation has actually found out that they are not sink holes but rather tunnel erosion so the project is also addressing that, to mitigate further erosion which leads to collapse of the ground. The last component is rainwater harvesting, we are installing four tanks to store rainwater which will be collected from various buildings in the airport to a total of about 7 Million liters.

The aircraft pavements have outlived their design life and had started to fail due to old age and fatigue. This has been manifested in deformation of the pavements as well as occurrence of potholes and as you are aware aircraft pavements have to be maintained at the highest standard and to be devoid of any potholes or any loose materials for the safety of the aircraft and the passengers in those aircraft. So it was deemed necessary that rehabilitation be carried out. Following intensive design carried out by a consultant it was revealed that we do not need a total reconstruction of this pavement save for a few portions?

Expectations for the project?      

We are looking to improve the pavements and give them a new lease of life, for another design period of 20 years. So this will enable us meet requirements of airport pavements which is very highly regulated.  The project will greatly enhance the quality of the facility and expect this to attract more clients in terms of airlines and other air operators and for those who are already there they will benefit by having a much smoother aircraft pavements meaning less wear and damage to their equipment and with the new AGL system the navigation safety of the aircraft is greatly enhanced.

Design specifications and considerations

I can start by letting you know that we have two runways at MIA; the main runway that is predominantly used by the large aircrafts and the secondary runway, a smaller one, to carter for the smaller aircrafts when there is a change in direction of wind because their landing and takeoff capability are susceptible to the strength of the wind. Then from the runways the planes need to access the parking bays where the passengers disembark and cargo is offloaded. The parking bays are connected to the runways through the taxiways. At the edge of the runways we have excavated in readiness to put up Air Ground Lighting to help the pilots be able to see the runway from a distance when they are still in the air.

The design is based on extensive investigations carried out on the desired and current strength of the pavement vis a vis the normal design procedure for airport pavements taking into account annual takeoffs. We procured services of the ministry of transport, materials department who carried out reflectometer tests on all the pavements within the airport whose report will inform us of the residual life of the pavement and give us an idea of what intervention measures to take.  These are then considered alongside other factors like the financial aspects and the regulators requirements.

In terms of the design criteria, the rehabilitation is basically reinstating the existing structure, milling off the aged weary course of the pavement and where the investigations indicated total failure then we carry out full reconstruction.

We do have two types of pavements; rigid and flexible. We use rigid pavements from Portland cement in areas where the aircraft will be standing for a long time and flexible pavements from asphalt in areas where the aircraft will be in motion most of the time. Some of the rigid pavements are still intact but in others we need to reinstate the sealant in the joints. If there is a small crack on a panel we will remove that section and reconstruct. If the entire panel has failed, most probably due to the base it is sitting on, then we will need to remove the entire panel and reconstruct it afresh.

Our drainage pipes had failed due to a number of reasons so drainage was not efficient and this encouraged tunnel erosion. The finer material in the ground was being washed away and of course it has a significant constituency in the soil so it increased the voids in the soil making them unstable which led to the collapse and hence what we initially thought to be sink holes. So we are reinstating the drains and also installing subsoil drains to hold back the fine material and prevent that phenomenon of tunnel erosion.

Rain Water harvesting …

This will significantly enhance the water storage capacity and this is free water from the rain. You can never say that you have adequate water supply and therefore the storage we are providing is to supplement what we are getting from the utility company but we shall definitely have savings in terms of our water bills at the airport an effect that should trickle down to all users of the airport.  The frequency of water shortages will be greatly reduced if not completely eliminated.

Engaged consultants and contractors

We procured the services of a consultant to carry out design review of the design that had been carried out, construction supervision and contract administration of the project. The other party is the contractor who was also procured through an international procurement bidding and a joint venture of Sogea Satom construction Company and Razel BEC of France managed to get the contract. They mobilized on site and they are continuing to execute the mandate of their contract.  As required by law they have involved local subcontractors to carry out various components of the work.

Local Capacity, Skills gap vs. available opportunities in the aviation industry

The capacity within Kenya has not really been figured up in terms of aviation engineering. There is no single university or college that trains Kenyan engineers to be aviation engineers and it requires proper training to be qualified as an aviation engineer. Based on that we can say that we are quite disadvantaged right from the word go. However in Kenya we still have quite a number of local consultants in aviation engineering, maybe providing just enough capacity to manage aviation consultancy.  I have to comment on the support we are getting from the Government through the authority itself and other development partners who provide for grants and other loans for the aviation training that I’m talking about.  We have quite a number of our engineers who have gone for these specialized trainings abroad and we can say that the capacity has improved significantly in terms of expertise but we are still not there. I’d wish there were aviation engineering courses in our universities or at least a specialist college.

There is a lot of expected expansion of aviation facilities in the country and in the region as well so opportunities are there for anyone willing to pursue.


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