Not All Secondary Containment Is Created Equal: Aesthetically-Pleasing Composite Walls




Editor’s note: This is the first 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.

 

Utilities have many options for secondary containment solutions, but not all containment is created equal! You’ll find there are pros and cons with all of them. For instance, installing fiberglass composite walls around a substation or transformer may be an aesthetic solution, but their beauty comes with certain tradeoffs. According to Dan Parker, President of C.I.Agent Solutions, based on feedback he’s received from our men in the field, composite walls are often harder to install than concrete. And they’re only slightly less expensive (usually just by 10% or less). Plus, once installed, the utility workers don’t really like having to step over them all the time.

But it’s not all negatives. Composite walls are strong, corrosion resistant and lightweight, and require little maintenance. And certain utilities believe the benefits of this application outweigh the tradeoffs.

That’s where we come in, with a variety of enhancements to make sure you get the maximum benefits out of a composite wall system. We want to share three scenarios in which our solutions are used in conjunction with composite walls for complete secondary containment assurance. However, we’d only recommend one of the following three applications.

 

Composite Wall with C.I.Agent® Oil Filtrion Panel side wall: Bad Solution

 
 

As you can see in the picture, they’ve added C.I.Agent® Oil Filtraion panels to the left of the composite wall. This is not a solution we’d recommend. The Oil Filtration Panel specs require a water flow rate of a minimum of 3 GPM per square foot of material with one foot of head pressure. It has a UV resistance of 70%, but only when covered with clean stone. Sitting out in the sun day after day deteriorates the geotextile, decreasing its life expectancy from 200 years to 5 years. It’s just not a suitable application for Oil Filtration Panels.

 

 

Composite Wall with C.I.Agent® Oil Filtration Panel Windows: Better Solution

 
 

For this substation, C.I.Agent® Oil Filtration Panel windows were added to the bottoms of the composite walls to allow water to flow through them but remove any hydrocarbons present. These walls were placed into trenches cut into the ground and partially covered with stone. Essentially, this system design is similar to the Geomembrane Liner and Oil Filtration Panel System, just utilizing composite walls instead of a polyvinyl blanket (though there’s still the issue of having to constantly step over those darn walls sticking out of the ground). While this solution is better than the previous because the Oil Filtration Panel windows in the trench allow for the one foot of head pressure required to maintain the water flow rate of 3 GPM per square foot material, they’ll still have to rake the stone around the walls regularly to ensure UV protection.

 

Composite Wall with a C.I.Agent® HFF (Oil-Stop Filter) in a Vault: Best Solution

 
 

Now here’s the perfect enhancement to complete a composite wall secondary containment system. There’s a drain in the left-hand corner of the wall that flows into a concrete vault housing an HFF. The location of the HFF in correlation to the walls provide more than a foot of head to ensure a steady water flow rate. If it detects a major oil release, the HFF automatically shuts off the flow. Not pictured is a grate that covers the vault. Even though you still have the walls protruding from the ground, this is the ideal solution when using composite walls for secondary containment.

 

Check back for next week’s post on concrete containment.

 

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