Crossing contamination off the risk list

Possible contamination can result from the wrong line-up of valves between storage tanks and jetty. Credit: Sofis
Possible contamination can result from the wrong line-up of valves between storage tanks and jetty. Credit: Sofis
Different grades of coal need to be kept separated. Credit - Marcel Oosterwijk, Flickr, CC BY-SA 2.0
Different grades of coal need to be kept separated. Credit - Marcel Oosterwijk, Flickr, CC BY-SA 2.0
Port water needs to be kept clean to avoid contamination. Photo Credit: industryandtravel, 123rf
Port water needs to be kept clean to avoid contamination. Photo Credit: industryandtravel, 123rf
Industry Database

Contamination can take many forms, but all could cost a port dearly. John Bensalhia reports

Contamination in the port environment takes many forms, some of which are easily avoidable, others requiring more thought and effort to address.

It could be a matter of mixing cargoes, inadvertently damaging adjacent stored cargoes, environmental pollution or another form of contamination. All share one commonality: they cost the port dearly in lower revenue and clean-up costs.

Accidentally mixing different types of cargoes can be easily done. Many bulk export terminals (coal, iron ore, other minerals) are common user facilities that handle many different grades of the material and with different material owners as well, points out Laurence Jones, director, global risk assessment, TT Club. To avoid contamination these materials must be stockpiled separately from each mine.

“For example, a coking coal costs, say, $150 per tonne and a steaming coal costs $110 per tonne,” he says. “If you have a stockpile of 100,000 tonnes of coking coal and accidentally mix some steaming coal with it, then the coal owner will seek damages of the difference in value (100,000 x 40 = $4m) as the coking coal is contaminated and is now only worth the value of steaming coal.”

Another cause can be damaging or contaminating adjacent cargoes: “Vehicles or other cargo can be damaged by sand blasting with abrasive or corrosive materials that are located adjacent to the vehicle storage yard,” says Mr Jones. He adds that mitigation of this risk would involve not having vehicles or other delicate cargo adjacent to open stockpiles of abrasive or corrosive materials, or stockpiling materials inside buildings or under tarpaulins to stop or reduce wind-blown dust.

Fall in value

Frank Gielissen, marketing director at valve operation specialist Sofis, explains that once contaminated, cargo is categorised as degradation product.

“When tank farms store different grades of oil, a mistake in valve line-up that causes a spill can devalue the product, meaning it has to be sold at a lower price. If a terminal were to inadvertently mix the products of two oil companies, the operator would also be obliged to pay both customers for the mistake. Depending on the scope of the spill and reach of the contamination, an entire batch could be ruined and have to be thrown away.”

As an added consideration, in the event of a spill, operators have a responsibility to report the incident to the local government or environmental agency. If an incident is not reported, or if spills become a frequent occurrence, governing bodies have the authority to close the facility.

The Port of Blyth provides an example of how to manage the potential problem of spillage. It has an oil spill contingency plan that complies with the UK’s 1998 Merchant Shipping Regulations and is approved by the UK Maritime and Coastguard Agency. The port also carries out an annual oil spill exercise in conjunction with other North East Ports Marine Group members.

The incorrect line-up of valves between the storage tanks and the jetty can also cause contamination, resulting in the loading of incorrect product or undesired product mix. “Not only does this represent a number of safety risks, depending on the transported chemicals, the cost implications can be giant for the tank terminal operator,” says Mr Gielissen.

He explains that there are various direct and indirect costs that a company could face when valves fail and product contamination occurs. “Direct costs involve product loss and clean-up. The cost per incident can easily be as high as €500,000, and that's without taking into account any fines, which could amount to thousands. Operational downtime is expected. Due to contamination and soiled product, operators may need to lower the cost of the product, or even discard it altogether and refund the customer in full.

“Indirect costs to businesses include environmental fines and reputational damage. Contamination or spills cost the industry millions every year, and the general rule is the polluter pays. In not so many words: you break it, you buy it.”

Environmental considerations

A key contamination issue for ports is how it can affect the environment. Air pollution, for example, can be caused by open stockpiles of dry bulk cargo, which are susceptible to wind-blown dust and contamination of adjacent properties. TT Club’s Mr Jones adds that a ship's stacks can create considerable smoke and pollution within the port.

There are two main options to mitigate the risk of air pollution from dry bulk stockpiles. “For small tonnages, stockpiling materials inside buildings or under tarpaulins can stop or reduce wind-blown dust,” says Mr Jones. “For large tonnages, extensive and automatic stockpile spraying to agglomerate the surface material is necessary to reduce the risk of pollution due to wind-blown dust. Additional mist sprays or dust extraction fans may also be necessary at hoppers and conveyor transfer points.

“Also, shore power is now being deployed in many ports and allows ships with shore power connections to connect and mitigate the use of the ships engines thereby reducing air pollution.”

Environmental considerations have been taken on board by global ports with respect to harmful emissions. The Port of Barcelona has pledged to reduce the number of carbon emissions to zero by 2020 through measures that are being introduced to reduce emissions to a minimum as part of a three-part BCN Zero Carbon programme. The plan involves the calculation of CO2 emissions from port activities, the action taken to reduce these levels, and finally, the purchase of carbon credits from reduction projects to offset the port's own emissions.

Water course

Water contamination is another problem, with the risk of dirty water entering the sea/river/harbour a major concern for bulk terminals. “Many terminals are now designed to contain dirty water within the terminal up to a 20-year storm,” says Mr Jones. “The rainfall from a 20-year or more storm will cause contaminated or dirty water to overflow from containment ponds causing pollution of adjacent waterways. Unfortunately, it appears with climate change that these 20-year storms are now more frequent.”

To combat this, Mr Jones says that the entire terminal site must be bunded or sloped to prevent dirty water due to operations or rainfall from leaving the terminal. “Normally, this would also involve water containment ponds around the terminal to provide initial collection of dirty water which is then transferred (pumped) to a main settling pond. The pond configuration and/or the addition of flocculants results in the agglomeration of the dirty particles in the water such that if the main settling pond overflows then the overflow water is clean.”

To tackle dirty waterways, the Port of Seattle has undertaken a clean-up project. Not only does this involve cleaning up the land, but also the waterways adjacent to it throughout the Puget Sound. The port explains that due to environmental impacts over the years and prior industrial activities before the port owned the properties, clean-ups ensure “responsible land and waterway stewardship”.

The Port of Blyth has also implemented a number of strategies to prevent contamination. The port performs maintenance dredging on an annual basis, with all dredged material deposited in a licenced area. Silt sampling also takes place regularly in dredge areas to make sure that there is no contaminated material.

Contaminated waterways can be caused by oil or other liquid pollution. “If an oil spill occurs in the waterways due to a leak from a liquid terminal or a ship, the port and/or terminal must have oil spill equipment to contain and collect or disperse the oil,” says Laurence Jones.

Human intervention

A final question remains: how much of the contamination risk comes from simple human error? And what can be done about this?

“Whether automatically loading or unloading bulk cargo to or from automated stockpiles, or manually handling with trucks, hoppers and portable conveyors on the quay, human error can result in mixing of different cargoes,” says Mr Jones. “Automation can reduce the chance, but it still relies on human intervention to confirm the correct train or truck with correct cargo.”

Mr Gielissen concludes that human error within valve alignment remains a concern. A solution is to completely automate valve opening and closing, but this can still have drawbacks. “It can be difficult to implement into plants that have limited existing infrastructure and automation and control. This is a high-end solution that works best in plants that are already largely automated, though most plants are not.” Additionally, the adoption of full automation comes at a “phenomenal” cost, he says.



ADDRESSING VALVE CONTAMINATION ISSUES

For tank-stored cargo, possible contamination risks can arise during product transfer. Contamination can result from the wrong line-up of valves between storage tanks and jetty.

Sofis' solutions allow the integration of manual valves into control systems. Real-time manual valve position indicators are mounted on top of a plant's existing valves detecting the position, which through a wired or wireless connection transmit the position of the valve to the control room. “This direct connection between the VPI and control room gives operators real-time feedback on the position and indicates when it is safe to commence product transfer,” explains marketing director Frank Gielissen.

A manual valve line-up system provides further control. “Mechanical interlocks offer real-time feedback on valves and prevents unauthorised operation in the field,” says Mr Gielissen. “Manual valve interlocks are mounted onto the plant's existing valves and require a key, unique to the individual valve, to open and close the valve. The keys are housed in the key management system which detects the presence of the keys, allowing complete visibility of manual valve operation.”

Right first time manual valve operations see the distributed control system determine the manual valve operation required. The chosen keys for release are communicated to the key management system.

“The key management system manages the release of a key to an authorised operator,” comments Mr Gielissen. “No key can be taken from the cabinet unless this has been authorised by the distributed control system for the specified valve operation. After operating the valves, the operator returns the keys to the key management system. Only when the valves are in the right position and keys are returned to the cabinet will transfer commence, allowing for no inadvertent operation in the field.”

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