Not All Secondary Containment Is Created Equal: The Burdens of Earthen Berms

Deciding what sort of secondary containment to implement at your facility to comply with SPCC regulations can be tricky. There are many options available, and all have advantages as well as tradeoffs. Some companies choose to utilize solutions that have a more “natural” appeal, such as earthen berms, as well as a couple others.

In the simplest terms, an earthen berm can be described as a level, raised bench or barrier, composed of the earth. The term berm derives from the French word berme, which means brim. The engineering of berms came about to aid the military during medieval times. Berms were used to ensure level space between defensive walls and adjacent steep-walled ditches or moats, and were intended to reduce soil pressure on the walls of the excavated part to prevent it from falling down.

In most cases, earthen berms sites require excavation and special equipment to install, and are subject to water and wind erosion, as well as animal burrowing. They often utilize clay or bentonite mixtures as sealants.

Free of chemicals, additives or anything toxic, sodium bentonite is an environmentally safe natural sealant that, when wetted by water, swells to 15 to 18 times its dry size. Clay liners obviously crack if they get too dry, though cracking will depend on the proximity to the water table and the how much it rains. Also, while a liner may be cracked at the surface, the cracks may not penetrate the entire liner.

The effectiveness of a liner depends on a variety of factors. If clay liners are exposed to liquids, they will swell and the cracks will close. Once created, because they will likely hold water, earthen berms still require ongoing O&M, such as the use of manual valves, pumps, water inspection before pumping, or oil water separators.

One solution for this problem is to add a synthetic membrane or filtration media to the mix, such as Barrier Boom – Secondary Oil Contaimment. Barrier Boom allows the unimpeded flow of water during normal rainfall or snow event, but becomes an impervious barrier in the event of an oil release.

Constructed from non-woven geotextile materials filled with oil solidifying polymers, a proprietary blend of USDA food-grade polymers, and backed with Agent-X, a non-woven geotextile materials with polymers embedded in the fabric, Barrier Boom is an accepted full containment solution for providing secondary containment as required by 40 CFR 112.7 (C) SPCC.

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Plus, if properly installed, it requires little or no maintenance and eliminates the need for other types of containment, sump pumps, oil-water separators, pits, manual valves and hydrocarbon detectors.

If the subsoil around the area to be contained is sandy or non-impervious, you may also need a liner for full protection, such as our Geomembrane Liner with Barrier Boom System. This containment system allows storm water to flow through the Barrier Boom side walls while removing hydrocarbons. In the event of a catastrophic spill, the side walls solidify and capture the oil, keeping it from escaping.

Another major drawback of earthen berms is that maintenance workers have to step over the mound or dike, and they can’t drive their trucks over them. For these situations, we recommend constructing a vehicle ramp of finely crushed, packed limestone on the earthen berm, so workers can easily drive up to the equipment. Driving over a berm without the ramp could crush the Barrier Boom panels and cause product failure. Just be sure to discuss this request with your engineer during the initial planning phase.

In this natural solution, dubbed "water gate," Barrier Boom panels are strategically placed only at the bottom of a grade to process runoff through a water gate. River rip rap is placed on both sides to protect the gate, then covered with stone to complete the installation.

Water is processed through Barrier Boom and a water gate

River rip rap placed on both sides protects the gate

The finished application is covered with stone

Contact BCI Today for More Info About our Secondary Containment Solutions

More than 10,000 substations worldwide use BCI oil containment systems. Click here to learn more about our integrated solutions. We can also help repair existing containment. Contact us to learn how we can help meet your secondary containment needs.