To support the drive for growth, Africa is looking to reduce reliance on imports; producing more of its own energy and raw materials. In Nigeria, this drive is led by businesses such as the Dangote Group of Companies, which is putting the finishing touches on the continent’s largest oil refinery in Lekki Free Zone, Lagos State.
The journey from Dangote’s new, purpose-built jetty to the construction site was more of a commute than a transportation; covering some 10 km. Over 52 000 t of components were planned for construction – including a 2000 t crude column and a 3000 t regenerator, the heaviest item ever transported on public roads in Africa.
The demands were not simply to move such exceptional dimensions and weights but also to ensure all components were coordinated to arrive in the desired sequence, minimising the risk of delays and additional costs.
Giuseppe Surace, Chief Operations Officer at Dangote Refinery, explained: “Our new refinery is the most ambitious project of its kind ever seen in Africa. Given the scale and importance of the work involved, we knew that we needed an experienced engineered heavy logistics partner who could successfully overcome challenges in the site terrain as well as the volume and size of construction components.
“This was key to ensuring that delays to our critical path were kept to a minimum, and that we are able to have the plant operational as quickly as possible.”
Avoiding that sinking feeling
The requirements in Lekki Free Zone were complicated by its location on reclaimed ground next to the coast. The new refinery required the team to tame the area of reclaimed swampland in order to turn it into a stable heavy lifting space, before work could begin.
To withstand the required weight and frequency of traffic, surrounding swampland needed to be reinforced. Conventional approaches to this problem include piling, or soil stabilisation, which requires excavation work and high volumes of aggregates. Although effective in providing the required stability, these solutions can be expensive, time consuming and in some cases can cause land reclamation problems later on.
Working with Nigerian partner Northridge Engineering, Mammoet was selected to meet this challenge. A solution was laid down that could support this web of logistical activity, providing the sheer strength needed to withstand the transport of such massive cargo across this former river delta.
This solution – Enviro-Mat – is a highly-developed soil improvement methodology, consisting of a combination of local soil, cement and additives including minerals, salt and zeolites, which increases ground bearing capacity up to 50t/m2. At Dangote, Mammoet applied this additive to laydown areas, hard stands and crane pads covering over 500 000 m2 of the site.
Harm Tiddens, Mammoet’s General Manager for West Africa, explained: “The need for ground stabilisation can have a significant bearing on projects, so using the Enviro-Mat system gave us some real advantages. Not only were we able to undertake lifts of up to 3000 t on reclaimed swampland, but the huge area stabilised proved crucial for laydown operations to continue smoothly throughout the rainy season – when this kind of land could otherwise be a challenge to operate on.”
All surface and substance
Seven Enviro-Mat yards were created, including laydown areas totaling 253 776 m2, assembly surfaces totalling 36 059 m2 and 78 heavy lift crane hardstands totalling 80 000 m2 – at a maximum rate of around 5000 m2/d. Following demobilization, these surfaces will either be reused as the base-course for new roads, or finely milled back into the local soil - without pollutants seeping into the groundwater.
Once fully operational later in 2021, the refinery will process 650 000 bpd of crude oil. It will transform the local economy, creating thousands of jobs and helping to secure a more prosperous future for African industry.
Expert planning was required to tackle the demanding scale of the Dangote refinery – in terms of cargo weights, volumes and the vast web of delivery schedules. Enviro-Mat provided the foundation for this transformation – turning barren swampland into a platform for meaningful economic growth.
Read the article online at: https://www.hydrocarbonengineering.com/refining/30032021/overcoming-challenges-at-the-dangote-refinery/