Not All Secondary Containment Is Created Equal
Deciding what sort of secondary containment to implement at your facility to comply with SPCC and EPA regulations can be difficult. There are many options possible, and all have advantages as well as tradeoffs. Some businesses choose to employ solutions that have a more “natural” application, such as earthen berms, as well as a couple of others.
In the most simplistic terms, an earthen berm can be defined as a level, raised bench or barrier, comprised of the earth. The term berm derives from the French word berme, which means brim. The engineering of berms was developed to aid the military during the medieval ages. Berms were used to assure level space between defensive walls and adjacent steep-walled trenches or moats and were designed to reduce soil stress on the walls of the excavated part to stop it from falling.
In most cases, earthen berms sites need excavation and specialized devices to install and are subject to water and wind erosion. They often employ clay or bentonite mixtures as sealants.
Free of synthetics, additives or anything toxic, sodium bentonite is an environmentally harmless natural sealant that, when wetted by water, swells to 15 to 18 times its dry size. Clay liners split if they get too dry, though fracture will depend on the proximity to the water table and the how much it rains. Also, while a liner may be broken at the surface, the cracks may not penetrate the entire coating.
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 Containment. Barrier Boom allows the unimpeded flow of water during average rainfall or snow event but becomes an impenetrable barrier in the event of an oil discharge.
Constructed from non-woven geotextile materials filled with Justrite oil solidifying polymers, a proprietary blend of USDA food-grade polymers, and backed with Agent-X, non-woven geotextile materials with Justrite 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.
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.
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Another major disadvantage of earthen berms is that maintenance workers have to walk over the mound or dike, and they can’t drive their vehicles over them. For these circumstances, we recommend assembling a vehicle ramp of finely crushed, compressed limestone on the earthen berm, so operators can promptly drive up to the equipment. Driving over a berm without the incline could break the Barrier Boom boards and cause product failure. Just be sure to discuss this request with your engineer during the initial planning phase.
In this natural solution, dubbed “Watergate,” Barrier Boom panels are strategically placed only at the base of a grade to process flow through a watergate. River riprap is placed on both sides to protect the entrance, then covered with stone to complete the installation.