What are Containment Structures?
Containment structures are any type of structure designed to contain leaks or spills of oil, fuel or chemicals from reaching the ground or reaching a water way and therefore prevent possible environmental impacts.
Examples of containment structures are concrete pads with concrete or block walls high enough to contain a leak. Plastic containment pads are also readily available for small containers such as 55 gallon drums. These structures are known as secondary containment.
What are the Regulations for Secondary Containment?
Secondary containment requirements are found in title 40 of the Code of Federal Regulations (CFR). Part 112 covers containment for oil and fuel, known as SPCC regulations, while Part 264, covers waste and chemical storage known as RCRA regulations.
The SPCC, Spill Prevention Countermeasures and Controls, regulations have been around for over 40 years. The regulations are found in the Code of Federal Regulations, Chapter 40, part 112. The main thrust of the regulations is to protect our water ways from oil or fuel spills. The regulations require that industries that store fuel or oil, in excess of 1,320 gallons, have a containment structure in place that is designed to hold the fuel or oil in the event of a leak or accident.
An SPCC Plan is also required. We can write your SPCC Plan. See SPCC Plans.
The RCRA, Resource Conservation Recovery Act, regulations govern chemicals and hazardous waste materials. The regulations are found in Chapter 40, Part 264 of the code of Federal Regulations.
What is the General Design Criteria for a Containment Structure?
EPA says that a containment Structure must be designed and operated as follows:
- The containment structure must be free of cracks or gaps and sufficiently impervious to contain leaks, spills and accumulated precipitation until the collected material is detected and removed.
- The containment structure must be sloped to allow for draining and removal of liquids resulting from leaks, spills or precipitation.
- The containment system must have sufficient capacity to contain rainwater. This is left up to the Engineer designing the system and considering where the system is located. Using 25 year rainfall event is a conservative approach that is commonly used. Also used is the 10 % rule, meaning that the containment structure should hold the volume of the tank plus 10 % for rainfall.
- Run-on into the containment area must be prevented.
Note: A roof over the containment structure is an option to building a higher containment wall.
Note: Check the soil type and loading requirements for any load bearing structure. Also, check compatibility of the materials of construction with the fluids being stored.
Wilson Environmental has structural engineers, licensed to practice engineering, that can help design and build your containment system.
What about Leak Detection?
Leak Detection may be as simple as a daily walk by to look for signs of fluid in the containment area. More sophisticated leak detection options are also available. A simple float switch that activates a warning light is an inexpensive option.
My Containment is Old and Cracked
Consider a spray in liner to seal the structure and prevent leaks. We can help with selecting and applying the correct spay in liner.
Wilson Environmental uses a 100% solids Polyurea liner coating that can be applied over concrete or cinder block containment dikes. The Polyurea forms a chemical resistant coating for most containment applications. Polyurea is the same material you see used in truck bed liners. It is extremely tough. For cinder block containment walls, the loose cinder blocks and cracks can be set and secured in place by coating with Polyurea material. The Polyurea material is sprayed in multiple passes to achieve a film thickness of 90 to 100 mils thick. For large voids or cracks, first fill with grout then apply the coating.
Always check with your local fire marshal for additional local requirements.
Understanding Your Containment Structures
Many containment structures that we inspect are essentially useless, and many do not meet regulations leaving the owner in a risky position. Even some containment structures made out of concrete that look good on the out side are worthless for containing the liquids they were intended to hold because of cracks. With containment structures, the amount of cracking that is permitted in standard structures or ordinary pavement may constitute a significant containment failure. As a result, alternative concrete design and construction standards which have been developed specifically for environmental concrete structures should be applied. These alternative standards are not included in typical engineering design curricula and, therefore, are widely unknown by most site design engineers. Building it right the first time will save you money over the long term.
Qualified Wilson Engineers
The principal engineers of Wilson are uniquely qualified to provide containment design engineering. These engineers have over 25 years of experience in:
- Industrial and petrochemical site development;
- Containment facility design;
- Geotechnical and structural design;
- Forensic investigations for failed containment structures;
- Wastewater and storm water collection, conveyance and treatment;
- Wastewater treatment plant design and operations; and
- Contaminated soil and sludge delineation, treatment and disposal.
A common misconception is that large, monolithic concrete pours which minimize the number of construction joints will result in improved containment integrity. In fact, studies of these large, monolithic pours have demonstrated a reduced containment integrity due to shrinkage cracking during the concrete cure and differential settlement after the concrete has cured.