Posted by Eric Boullenois - 09 December, 2019
Today, operators of processing plants such as petrochemical and other chemical plants must have plans and measures in place to contain a hazardous spill of chemicals that can contaminate soil and water under most countries’ environmental regulations. While the fastest response teams are often in place, basins should hold the substance for a certain acceptable period and resin-based lining systems can help increase the holding times. In this article I am going to describe why hot spray systems are particularly well suited to fulfill the specific requirements of secondary containment and offer long-lasting protection even if cracks appear in the structure.
The primary containment is considered to be the vessels in which liquids are stored. The main function of the secondary containment is to temporarily and safely contain any accidental liquid spill in a second basin until response teams arrive and the plant has been safely shut down. Figure 1 shows a schematic and simplified approach to spill containment. In addition, tertiary safety measures such as emergency shut down systems and quick-response plans by the fire departments can help reduce the environmental impact of any spills which may occur.
In the case of a spill or leak, the liquid can then be safely collected from the basin and disposed. Local codes and regulations define standard response or chemical exposure times which a basin must be designed to withstand. In the past, techniques such as retention basins consisting of reinforced concrete slabs and walls were very common, but over time cracks may occur in any concrete structure posing the most common problem for inspectors and operators. Today modern resin based lining solutions can offer more effective cleanup and protection from spills, if these solutions are designed correctly.
Long-term durability may not always be essential in the case of contact with the retained liquid or spill substance. The lining is typically only required to last hours or days but not weeks and according to the operating plants clean-up response times. A sacrificial cost-efficient lining could be the ideal solution depending on your plans and willingness to handle this risk.
When specifying chemically resistant resin-based lining systems, it is important to remember that no one product will be resistant to all chemical products or substances likely to be present.
The most typical product requirements for linings can be divided in the following three categories: performance, design & installation, service.
How to select the right solution for secondary containment waterproofing?
We can summarize the key steps for a reliable secondary containment project in the following list:
- Site survey of existing conditions (or periodic site checks)
- Concept development including constructability review
- Chemical resistance and performance criteria selection – also the temperature of chemicals stored must also be carefully considered, for a practical example please see the article Hot stored chemicals: calculation of surface temperature and reduction of up to 30% in repair costs
- Approval of concept by operator
- Detailed design and cost estimate
- Tendering and contract award
- Installation including stringent quality control/acceptance
- Return to service time calculation or estimation
Last but not least a review of performance criteria and the risk of failure in the event of a chemical spill are extremely important for successful project implementation.