Not All Secondary Containment Is Created Equal: Tricks and Treats of Leaving a Smaller Footprint

Editor’s note: This is the fourth in a series of posts discussing all of the various secondary containment solutions available, subsequent tradeoffs and/or maintenance associated with each, and how C.I.Agent Solutions offerings can enhance the different containment systems. Today’s post focuses on containment solutions with a small environmental footprint. Check out previous posts about composite walls, concrete, and natural containment.


We all want to do our part in taking care of this wonderful, sustainable eco-system known as Earth. As Halloween approaches and a kaleidoscope of colorful leaves slip toward the ground, we are reminded that our time wandering over her landscapes will be brief, in the grand timeline of the universe, but that doesn’t mean we should be inconsiderate as we pass through. As humans, limiting or minimizing the ecological footprints we create should be something we strive to do. After all, are we not but caretakers of our great-great-great-great grandchildren’s home?

While ensuring utilities maintain adequate secondary containment methods to comply with SPCC standards is important to preventing oil pollution and contamination of groundwater, it still has some negative effects on the environment. The construction equipment necessary to install a secondary containment system consumes a vast amount of energy, not to mention the manufacturing and transportation required for each system. Once we add human labor to the mix, we’re talking about paying a lot of GREEN (as in greenhouse gas emissions) for some Lebron James sized shoes (as in an XXL carbon footprint)!

We’ve worked with several companies over the past few years that requested a “smaller footprint” solution, due to either lack of space/land restraints or a goal of helping the environment in whatever ways possible. In some cases, a solution such as above-grade fiberglass composite walls may work, but they do come with certain tradeoffs. However, in lieu of Halloween, we’d like to share a “trick” for leaving a smaller footprint and the “treats” that come with it. A design and procedure developed by Burns & McDonnell tackled this problem head on by adopting the practice of using ADS perforated pipe (PVC works as well) in the floor of the containment units to increase the oil capacity … and reduce the size of the footprint of the containment area.

The trick to creating a smaller footprint is to utilize void space in whatever way possible – even if it means creating it yourself!


When originally drawing the design, we planned on using the C.I.Agent® Geomembrane Liner system on containment sumps of 75’ x 42’ x 54” for 345/138kV transformers with capacities of 30,000+ gallons. Using perforated ADS pipe with a 36” diameter reduced the containment dimensions to 38’ x 28’ x 54” – with the same capacity! This method has also been successful for smaller transformers using ADS pipe from 12” to 24” I.D.

This method has also been successful with using 12” to 24” perforated piping. The piping will then be covered with a minimum of 12” of stone.


The volume of oil capacity is increased exponentially using the pipes. Let’s go over the math. Normally, when calculating containment capacity for a Geomembrane Liner system or Oil Filtration Panel, we use the following:
1 cubic foot = 7.50 gallons of capacity
1 cubic foot of stone = 3 gallons of capacity at 40% void
However, in this case, because the area of a circle gives you the square footage times the length of the pipe times the gallons/liters, we get about a 99% void area rather than the 40% void we get in the stone. That’s a neat trick, right?

Now for the treats! Some of the many benefits of applying this method instead of other methods is that it requires less of the following:

  • Excavation: You’re not taking up as much space, so you’re dealing with less dirt than when using stone.
  • Disposal of dirt: This one is obvious – less excavation = less dirt.
  • CIAS materials: The containment area isn’t as spread out, so the Geomembrane Liner isn’t as big. You also won’t need as much Oil Filtration Panels because there will be fewer windows.
  • Gravel and stone: The piping provides the void space and then some. All you need is the backfill stone to cover the pipes, and a minimum of 12” of stone above the pipes.
  • Labor & Time: Less excavation, dirt disposal, materials to install and gravel obviously means it won’t require as many people to be involved or the install to take as long as one with containment twice the size.

The piping must be perforated to ensure the void space, otherwise you defeat the purpose of this technique. All of these installations were also covered with between 12” and 18” of clean, washed and screened stone to provide fire quenching.

Hope everyone has a safe and happy Halloween!


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