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

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)!

The trick to creating a smaller footprint is to utilize void space in whatever way possible

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 the spirit 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 (or any type of corrugated HDPE pipe) in the floor of the containment units to increase the oil capacity … and reduce the size of the footprint of the containment area.

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

This method has also been successful with using 12- to 24-inch perforated piping. Cover the pipes with a minimum of 12 inches 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 with Barrier Boom system, we use the following:

1 cubic foot = 7.50 gallons of capacity
1 cubic foot of stone = 3 gallons of capacity at 40 percent void

But, 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 percent void area rather than the 40 percent void we get in the stone.

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.
  • Containment installation materials: The containment area isn’t as spread out, so the Geomembrane Liner isn’t as big. You also won’t need as much Barrier Boom because there will be fewer windows.
  • Gravel and stone: The pipes provide the void space and then some. All you need is the backfill stone to cover the pipes, and a minimum of 12 inch of stone above the pipes for fire quenching.
  • Labor and 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 pipes must be perforated to ensure the void space, otherwise you defeat the purpose of this technique. All installations were also covered with between 12 and 18 inches of clean, washed and screened stone to provide fire quenching.

Contact Justrite for Secondary Containment Solutions for a Smaller Footprint

If you want below-grade secondary oil containment but have space or depth constraints that require a smaller footprint, we can help maximize your containment capacity. Justrite offers multiple systems to fit your site-specific needs - contact us for a quote or more information today.

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