Choosing the Right Liner
Corrosion Resistance
Brine ponds are particularly challenging when it comes to containment. Salt, especially in high concentrations, is very corrosive, while the presence of other dissolved minerals in the solution only intensifies the effect. Even metal storage tanks with protective coatings react to these corrosive properties, and metal fixtures in any kind of brine pond will eventually rust away.
Concrete and clay (bentonite) liners also degrade more quickly in the presence of concentrated brine. In fact, bentonite is doubly unsuitable, since it is highly prone to cracking as the water evaporates and it dries out. HDPE and LDPE, which are rated as “good” chemical resistance, are nevertheless unable to stand up to concentrated brine. In the presence of such highly corrosive fluids, both materials degrade quickly. Clearly, “good” resistance is inadequate this case.
A multi-layer material, like reinforced polyethylene (RPE) from BTS Liners, is rated “excellent” for chemical resistance. Clearly, ArmorPro's unparalleled ability to resist corrosion and its outstanding durability against abrasion, tears, and punctures, makes it the most effective choice for this type of containment challenge.
UV (Sunlight) Exposure
Brine and other types of evaporative ponds receive significant amounts of exposure to sunlight’s harmful effects compared to most kinds of storage or treatment ponds. Since the whole goal of the pond is to remove water through exposure to air and sunlight, a pond’s sides and bottom will naturally be exposed over time. Even the formation of crystals along the bottom and sides don’t provide protection from UV radiation - they reflect sunlight through to the liner and multiply the exposure.
Sun exposure is a significant concern for brine ponds because UV waves break down the molecules in many liner types - PVC is particularly vulnerable here - causing them to degrade rapidly. The liners typically become inflexible, weak, and particularly vulnerable to tears. Caustic and dangerous liquids should never be maintained in conditions like this - a leak or, worse, a significant spill is all but unavoidable.
Reinforced polyethylene liners use a multi-layer construction that’s extremely resistant to UV damage. In particularly challenging situations like these, additional coatings can be added that will further extend a liner’s life by several decades. When it comes to protection against the sun’s damaging rays, BTL’s ArmorPro products are the best choice.
Abrasion and Wear
Ponds intended for harvesting crystallized minerals and salts tend to experience more mechanical damage than most other ponds. The use of heavy equipment to gather and shape minerals into mounds and then remove them exposes the liner to significant wear and tear. Even newly installed PVC is simply too vulnerable to tears to use in this kind of application. Other materials may be tough enough at the outset, but over time are likely to weaken with wear and tear. RPE is constructed with a reinforcing scrim between layers of impermeable membrane, rendering it exceptionally tough, resistant to tears, punctures, and damage from stretching. This kind of durability virtually eliminates the need for multiple repairs every time product is harvested from your ponds.
Installation
Many simple containment ponds can be lined with concrete or with a relatively thin layer of clay or gravel in order to perform adequately for years. But because brine is such a hazardous liquid, the use of high-quality, flexible geomembranes is a must, regardless of the composition of that specific brine.
Typical challenges with flexible geomembranes like EPDM and HDPE are their weight, which makes shipping in large panels impossible, and further complicates the installation process simply because it’s hard to handle. Using smaller panels is the only option for those, but that increases the need to join many pieces together on-site. The necessity for on-site sealing not only delays installation (and associated costs) but significantly multiplies the chance that a seam will be improperly sealed or that it will eventually fail. Some materials can only be seamed using adhesives, which are one of the least reliable and most time-consuming methods.
RPE is lightweight and extremely flexible, so it can be fabricated and shipped in panels that cover hundreds of thousands of square feet. Any seams that are required on-site use thermal welding, a powerful bond that does not degrade over time. The seaming process is simple and quick, with fewer opportunities for human error. Even so, seams do always present a higher probability of leaks , so it’s important to minimize those seams whenever possible. As a leader in the industry, BTL Liners is known to fabricate the largest geomembrane panels in the industry, some in excess of 150,000 feet.
Special Situations
Backup Protection
Brine mixtures are toxic to many wildlife, agricultural land and freshwater ecosystems; even at relatively low concentration. Therefore, they require careful and effective containment to protect the local environment. However, the most toxic, contaminated, and concentrated brine mixtures need more than a single layer of liner for adequate protection. Anytime a spill or leak risks serious health or environmental damage, a double lining is your best option. Fortunately, this additional security is more sophisticated than simply laying one liner on top of another or covering it with cement. Instead, the process generally involves laying a highly durable liner directly on the ground, followed by a thick layer of fine dirt that will serve as a sort of sponge to absorb any leaked brine before it reaches the secondary liner. This absorbent liner should include continuously monitored leak sensors that will alert if the “sponge” is getting wet so that repairs can be performed well in advance of any leaks to the environment. These leak detection sensors are usually installed underneath brine pond liners in any case, but for ponds containing exceptionally risky liquids, a secondary liner is essential.
Concrete Storage Ponds
Larger ponds with a surface area of an acre or more, or in situations where the pond is planned for long-term storage, may be designed with a concrete liner, which helps keep the soil stable in situations where complete stability over time is a critical element. Still, concrete is surprisingly porous, so it requires an impermeable membrane between the soil and the concrete. This liner prevents concrete from soaking up moisture from the soil and transmitting it into the brine pond.
