All pit liners break down eventually, but some geomembranes are more durable than others. Protecting produced water pit liners from damage is only possible once you understand the potential causes. Not all produced water pit liners are at risk for the same types of damage. Plan out proactive approaches to prevent each of these potential damaging effects to extend the life of the liner and save money on repairs for years to come.
UV rays degrade all of the polymers used for geomembranes and flexible liners, but they vary greatly in their resistance to this kind of damage. Even membranes that share similar polymer formulations can differ in UV resistance depending on the precise product. Coatings, additives, and treatments can greatly extend the lifespan of a liner installed in an exposed pit that has no cover. If it’s necessary to temporarily use a less UV resistant liner to control produced water loss, it may be best to add a layer of sand or concrete between the geomembrane and the wastewater. This prevents UV light from reaching the flexible liner and rapidly degrading it.
If there’s not enough care taken to match the liner material to the hydrocarbon content of produced water, the oil and gas residue will quickly break down the geomembrane. Some liners appear to have good compatibility with these compounds for years and then suddenly degrade at one point. Look for manufacturers that have long-term test results to show how their products perform when exposed to hydrocarbons and similar compounds. You don’t want to install a liner expecting 20 or 30 years of performance only to have it suddenly fail just 5 years after installation. Liners for produced water pits need both short and long-term resistance to these chemical compounds.
Other Chemical Reactions
Don’t underestimate the potential for other reactions with minerals and chemicals mixed in with the fracturing fluid. Heavy metals and volatile organic compounds (VOCs) are particularly prone to reacting with liner materials and causing damage. Treatment processes also produce new and unexpected chemicals and compounds to react with each other and the liner. Taking samples of the potential water and determining its chemical makeup is the best way to determine which liner can best handle the specific mixture you need to store.
Mechanical damage most commonly occurs during installation. This is due to the need to stretch and drag large and heavy sheets of liner over the ground to cover it. Cutting smaller rolls of liner allows for faster handling, but it slows down the covering and seam sealing process alike. Reducing the number of seams means using larger rolls. The heavy equipment required to carry and spool out these rolls can easily damage the liner itself by applying too much pressure or rolling over existing material. Plan out installation carefully to prevent these problems. Accessing and cleaning the pond or pit later can also damage the liner, especially if it’s exposed over the banks and edges. Consider paving over part of the bank so trucks and tankers can easily access the pit for pumping as needed without damaging the liner.
Roots and Rocks
Don’t forget about dangers from below when planning to protect a produced water pit from damage. Roots growing from nearby trees easily penetrate thinner and weaker liner materials. Reinforced materials like RPE are more resistant to this kind of damage than single layer liners. Even when care is taken to prepare the soil and remove existing rocks, new stones migrate to the surface over time. The frost and thaw cycle is particularly prone to bringing sharp new rocks to the surface. Much like with tree roots, reinforced liners are better at resisting damage from below than other materials.
Installing an underlayment for the liner is one of the best options to increase damage resistance in addition to choosing the right material. Underlayments are thicker membranes that aren’t designed to hold water but to cushion and protect the liner instead. These materials stop tree roots, rocks, and even burrowing animals from digging into the liner. BTL Liners reinforced products can easily be installed without underlayment, but we also provide compatible protection for challenging sites that demand it.