1 Engineering Integration at Work
Civil Engineering Works at Tank Farms: Tank farms are exciting places for engineers: there are a few examples of how various engineering disciplines have to co-exist, cooperate and integrate as much as in these intimidating, imposing and impressive facilities. Most people think tank farms, with their storage vessels, pipes and pumps, are the exclusive hunting grounds of mechanical and chemical engineers, while civil engineering is about structures, roads, water and concrete, right? Exactly… but let’s start with a bit of context.
2 The Business of a Tank Farm
The storage of hydrocarbon and other chemical products is necessary for many sectors of the economy to support industrial or commercial operations.
At the large enterprise end of the spectrum, tank farms are built to receive, store, process, and distribute products to consumers. This often means that the facility is geographically placed at the interface between transport modes—for example, to receive the product from an off-shore pipeline and deliver via dispensing trucks or rail. At the smaller end, a tank farm may be built to uniquely serve the operations of a factory or airport operations and secure supply continuity.
Mega tank farms, some owned and operated by governments, are used as buffers against the volatility of price or supply. One of the largest tank farms on the planet is located in Pengerang, Malaysia: the site can hold 420,000 cubic metres of crude (2.6 million barrels) and provides blending and distribution services. The Houston Fuel Oil Terminal Company, reportedly the largest oil storage terminal on the US Gulf Coast, has a capacity of more than 13.8 million barrels. In the Emirate of Fujairah, the UAE is building the world’s largest underground crude storage facility with a capacity of 42 million barrels. Imagine the size of this thing!
Notwithstanding size and purpose, all tank farms are business enterprises in their own right. In addition to the commercial motive, their continuity, safety, efficiency, and environmental impacts are the topics of compliance with regulations and service level agreements with consumers. The facility has to be designed against the backdrop of these realities. Enter the civil engineer.
3 Tank Farms as Strategic Facilities and Key Points
Petroleum products and other chemicals are undeniably critical to the functioning of every economy on the planet. If an airport tank farm ceases operation, planes don’t take off. If the fuel supply at a commercial farm runs out, crops don’t get harvested.
The risk goes beyond economics: tank farms are hazardous places. Fires, explosions, and chemical releases risk humans, infrastructure, and the environment. Because of where they are placed, catastrophic failures at tank farms will create disastrous effects. Safety and Reliability Engineering, Fire Engineering, and Control and Instrumentation (C&I) are key disciplines in tank farm operations and utilise sophisticated early warning detection, protection, and shut-down systems.
More than one-fifth of tank farm failures are attributable to human error, and over half are due to tank failures. Advances in IoT, automation, digitalisation, artificial intelligence, predictive maintenance, and geomatics reveal new opportunities for engineers to understand, anticipate, predict, and mitigate risks. The growth in global environmental awareness and political (and statutory) and societal pressures to reduce carbon emissions will accelerate these developments.
Tank farms are ideal targets for malicious attacks. They require physical security and protection infrastructure and management systems worthy of a military installation. Here, too, there is a rise in the application of AI and intelligent detection science. Given the obvious implications for designing physical infrastructures such as perimeter walls, access points, canopies, and internal protective walls, the civil engineer is a key member of the professional team responsible for security.
4 Standards and Specifications
Why standards and specifications? Consistency, efficiency, quality, and integrity of design and operations are the keywords here for all the good reasons of safety, security, and environmental protection already mentioned. Knowing the integrated system of standards informs the civil designs and construction works in tank farms is useful.
The petroleum industry relies on national and international bodies to develop specifications and codes of practice. Examples are the International Organisation for Standardisation (ISO), the American Petroleum Institute (API), the British Standards Institution (BSI), the American Society of Mechanical Engineers (ASME) and the Society for Petroleum Engineers (SPE). Their specifications and codes, specifically those of the API, are considered the de facto international standards and often form the basis for national or regional standards. However, in a particular country or region, there will be differences that account for local contexts and practices.
The Association of Oil and Gas producers explains the hierarchy of standards as follows:
The need for a harmonized global approach has been pushing the industry towards international standards based on the ISO system. Several API codes have already been transferred to ISO to become global ISO standards. 
Safety, health, and environmental protection, in conjunction with best practices in quality management – collectively, SHEQ – are disciplines that are in their own right. Practitioners qualified to implement an integrated SHEQ management system comprising safety and health (OHSAS 18001 or its local equivalent), environmental management (ISO 14001) and quality management (ISO 9001) are mandated and indispensable role players in petroleum projects and operational teams.
Engineers are used to working with standards, so there is nothing new here: there are industry-specific design codes for fuel tanks, pipes and pumps, reinforced concrete structures, earthworks and treatment of contaminated effluent, and specialists are no strangers to these. For civil engineers, the challenge is to discover how the standards applicable to tank farms inform and shape their application of discipline-specific standards: the design of a drainage system is simple enough to do, but it has to comply with the requirement to separate contaminated- and stormwater run-off. It is often at the interface between a civil design and a mechanical system where detail is overlooked.
The engineering disciplines involved in a tank farm do not act in isolation – to develop a solution, they have to integrate their respective contributions, cooperate with SHEQ practitioners, planners, architects, environmental consultants and C&I specialists, and account for the operator’s management system requirements. This says a lot about the need for civil engineers to widen their scope of consideration, bring systems thinking to the table and become acquainted with new technologies. A new breed of civil engineers is in the making…
5 Civil Engineering Works: Facilities and Services
5.1 Roadways and Platforms
Except in the perfectly automated tank farm of the future, vehicles and people are integral parts of the facility. Fuel dispensers and loaders manoeuvre to loading and metering bays, service vehicles carry technicians between workshops and pump bays, personnel walk from point to point, contractors and visitors arrive, park and leave. These movements require roads, parking areas, and various types and sizes of platforms.
Civil engineering comes into its own in this domain – the site layout plan is a starting point, accompanied by a conceptual design to serve operating requirements. Basic designs will consider design vehicles (i.e. vehicle classes, their operating loads and speeds, and turning circles), pedestrian movements, tank farm operations, drainage and soil conditions. The geometric design will specify gradients, space and layouts to optimise earthworks, assist operating flows and ensure the safety of movement. The roadway and platform design will put down a layered structure capable of carrying vehicles over its design life (often 20 years and more) and channelling rainwater run-off.
It is common for detailed road designs to consider several options. Roadways and parking surfaces could be built of gravel, asphalt, or concrete, and drainage could be along open (grated) channels or pipes. When making a detailed design recommendation to the client, the engineer evaluates the options by considering the appropriate standards, soil characteristics, available materials, constructability and economic parameters, and the impact on operations and maintenance.
Tank farm loading platforms must be impermeable and resistant to damage by the product and fire, and containment must be provided in the case of spillage. This mostly leads to the decision to use Portland cement concrete because it presents a life-cycle cost advantage with regard to maintenance.
A critical input to the design work is a geotechnical survey, which will assess the geology of the site and the surrounding area, collect meteorological and hydrological data, assess seismic activity and perform in-situ and laboratory tests of soil characteristics. These surveys and tests must be carried out by a geotechnical specialist who will produce a report with recommendations about drainage, the suitability of in-situ materials as foundations, and special soil treatments that may have to be applied. Of specific concern to civil engineers is the presence of clay (which would be susceptible to heave and settlement), collapsible soils and corrosive materials. Soil mechanics, a discipline of civil engineering, is a well-established science and design code that makes provisions for handling the variety of conditions likely to be encountered during projects.
5.2 Buildings and structures
Planners and architects will play the leading role in designing administrative buildings and workshops, paying due attention to the relevant building codes, safety specifications, functional requirements, and human needs. Working in a tank farm is a hazardous business, and the intention is to make these facilities comfortable, functionally effective, safe, and, increasingly, green.
These designs should include the inputs of civil engineers and their colleagues from the oil and gas and C&I disciplines, who can incorporate the constructability of designs and requirements for safety and effective interfaces to operations into the planning. The designs and construction must achieve structural and functional integrity, for which the civil engineer will complete detailed designs of columns, footings and foundations, reinforced concrete walls, floors and roofing structures.
Similar to the requirements for roads and platforms, the site’s geotechnical characteristics will be prominent in the design of footings, foundations, and structures that will withstand lateral pressures, seismic activity, and the design loads.
Of course, the civil engineer’s responsibility does not end with designs. During the procurement and construction phases of the project, she made a critical contribution to oversight, quality control, and commissioning. In these matters, the engineer’s primary accountability is to produce an outcome consistent with standards and protect the client’s and facility users’ interests.
5.3 Drainage
When it rains, water wants to run to the lowest point. During heavy downpours, this run-off can flood operations and become a safety hazard, in few places more acute than a tank farm with its containment structures. Civil engineers consider hydrological information and geotechnical surveys to design drainage capacity for the water volumes generated by a storm size of selected recurrence probability, such as a 1 in a 20-year flood. Drains must have a specified minimum gradient of 0.6% to prevent the drainage system from acting as a reservoir and carry run-off away quickly and effectively.
Contaminated runoff is particularly important to design because industry codes require the separation and containment of such effluent. To prevent contamination of external stormwater drainage systems, effluent drainage should be capable of being released to natural courses only when it is safe to do so, namely when hydrocarbons have been sufficiently separated and removed to achieve water quality in keeping with local discharge standards.
Civil engineers design the structures, pipes and channels that carry and contain spillage and contaminated run-off. The containment structures typically include bunded areas (say around pump bays), separator vessels (in which contaminated effluent is treated mechanically, chemically or organically) and attenuation dams (to contain a sudden large volume of run-off and control its release). These structures require a civil engineer to design their capacity (again, industry codes prescribe the standards and parameters for use) and functional operation. Separator tanks could be built on-site as a reinforced concrete structure, but specialised vessels and technologies are also commercially available. No matter the type, containment and treatment vessels require earthworks and foundations, which are uniquely civil engineering territory. Again, geotechnical information is an important input to the design process.
Spillage in tank farms has the potential to permeate and contaminate groundwater. Many tank farms include monitoring wells in their designs to enable continuous measurement, reporting, and planning to mitigate the risk of pollution. The geotechnical survey is of great assistance here because it will identify the level of the groundwater table and how in-situ materials may assist or impede the ingress of contaminants.
5.4 Special structures and facilities
Tanks in a tank farm, and any other functional system that may spill hydrocarbons (e.g. the loading bay), have to be placed in bunded containment areas, for which there are specific standards and design requirements. Bund walls and floors must, for example, be water-tight and able to withstand the rush of a large volume of fuel in the event of a tank rupture. This translates into reinforced concrete retaining walls and foundation structures for large vessels. This translates into more civil engineering design and construction work.
Around a tank farm, various functional systems, such as filter bays, loading bays, and pump stations, are placed on foundations and bunded platforms that are impermeable and resistant to damage from products and fire. Of course, they can accommodate the static and dynamic loads imposed on them. Their protection with firewalls and canopies to direct rainwater elsewhere requires structural design work. Think civil engineering again!
Appurtenant to these structures is the steel furniture of elevated walkways and stairs, inspection gantries, work platforms, and structures to support overhead cranes, pipes, and equipment. The civil engineer with a love for steel has all the challenges to be desired!
6 Conclusion
Civil engineers have always been, and will remain, an indispensable element of how tank farms are planned, designed, built and operated. It is just that their contribution is not that visible to the casual observer, what with the size of the thing and all the intimidating tanks, pipes, pumps and valves around. Look a little deeper, and you will discover a world with magnificent challenges and exciting solutions for which civil engineers are uniquely qualified. Here’s to the civil engineers who make our buildings trustworthy, our roads and dams functional, our tank farms productive and safe, and our world overall a better place to live in!
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7 References
https://oilfiltration.globecore.com/characteristics-types-purpose-tank-farms/
https://www.eia.gov/todayinenergy/detail.php?id=21552
http://lightningsafety.com/nlsi_lls/Causes-of-Failures-in-Bulk-Storage.pdf
https://www.tankstoragemag.com/display_news/10521/ADNOC_to_build_worldrsquos_largest_underground_crude_oil_storage_facility/
Florea, Gheorghe and Popa, Marian – Safety and Security Integration in LPG Tank Farm Process Control in Proc of the 14th IFAC Symposium on Information Control Problems in manufacturing, Bucharest, May 2012
https://www.digitalrefining.com/article/1001311,Automation_of_tank_farm_systems.html#.XjEq5y17FsY
https://www.extractiveshub.org/servefile/getFile/id/5185
http://www.ogp.org.uk/pubs/426.pdf
http://www.iogp.org/wp-content/uploads/2016/12/Standards-Issued-2017.pdf
https://www.sciencedirect.com/topics/engineering/tank-farm
To all knowledge