Dirt is a Risky Proposition
It’s the question every landowner asks, and it’s a fair one: “Do I really need to spend the money on a liner?” For a simple farm pond where you’re just hoping to hold some rainwater, the answer might be no. But for a high-performance waterfowl impoundment, the answer is an emphatic yes.
Even for a simple farm pond, relying on native soil to consistently hold water in almost any situation is a gamble. After all, “good” soil can still have hidden sand lenses, develop cracks, or be riddled with animal burrows. For a high-performance waterfowl impoundment that depends on precise, active water management, a soil liner is an unforced error.
No matter where you get it, water is your most valuable resource, and trying to make up for seepage losses is as fruitless as trying to keep a punctured tire inflated. It wastes money, strains your water source, and undermines your ability to manage the habitat effectively.
The Bottom Line
A liner for a waterfowl impoundment has one job, and it should do it perfectly: it should separate your water from the dirt, making the question of whether your soil has good soil or hidden sand lenses completely irrelevant. The impermeable foundation a liner provides keeps what you’ve collected or paid to pump right where you need it, giving you complete control over your most valuable resource.
The Traditional Method: Compacted Clay
For thousands of years, the only way to create a durable, waterproof material—from drinking vessels to pipes—was with baked or unbaked clay, and today it (the unbaked version) remains a common solution for lining ponds. It requires finding a source of high-quality plastic clay, hauling in thousands of tons, and then carefully spreading and compacting it in thin, controlled layers (called “lifts”) to create a dense, low-permeability seal.
Pros
Clay liners use “natural” materials, and their creation is a well-understood earthmoving practice.
Cons
Clay liners are inherently risky and come with hidden costs, making them a poor choice for a high-performance impoundment.
Materials
Material sourcing is a gamble: good, clean clay isn’t available everywhere. If you don’t have a suitable source on-site (and most properties don’t), the cost of hauling it in can be astronomical, often exceeding the price of a modern geomembrane.
Installation
Installation is slow and technical: properly compacting a clay liner is a highly skilled, weather-dependent process. A sudden rainstorm can turn your site into a slippery, mucky swamp, and achieving the correct moisture and density requires constant on-site testing. A single wet day can significantly delay your construction timeline while you wait for the clay to dry.
Vulnerability
Clay liners are prone to failure. If the impoundment ever fully dries out, clay can develop cracks, crumble, and erode. They are easily compromised by burrowing animals like muskrats. And a single mistake during compaction can create a permanent weak spot that will leak for the life of the project.
The Modern Solution: Reinforced Polyethylene (RPE)
Reinforced Polyethylene (RPE) is the modern, engineered solution for impoundment linings. It’s an advanced composite material created by laminating durable polyethylene film over a strong, woven reinforcement grid (or “scrim”). This design directly solves the primary weaknesses of traditional methods and older geomembranes: inconsistent performance, heavy weight, and inefficient installation.
Pros
The advantages of RPE are best understood in terms of performance, installation, and overall cost-effectiveness.
Performance
RPE’s greatest strength is its exceptional strength-to-weight ratio. The internal scrim provides incredible tear and puncture resistance, making it significantly tougher than non-reinforced liners (like standard HDPE or PVC) that must be much thicker and heavier to provide the same durability. This durability makes it highly resistant to damage during installation and from the operational stresses of an impoundment, including burrowing animals and maintenance activities.
Installation
Unlike clay, which is slow and weather-dependent, RPE installation is speedy and efficient.
- Because it is so strong and lightweight, RPE can be factory-fabricated into massive, custom-sized panels—often over an acre in size—that are accordion-folded or rolled for shipping and easy deployment.
- This dramatically reduces on-site seaming by up to 80% compared to materials (like HDPE or EPDM) that ship in small rolls.
- Fewer seams mean faster installation, lower labor costs, and a much higher level of quality control, as most seams are completed in a controlled factory environment.
Cost
While the per-square-foot material cost of RPE may be higher than some basic liners, its Total Installed Cost (TIC) is almost always significantly lower. The considerable savings in labor, on-site equipment time, and a compressed construction schedule make it the more cost-effective choice for a high-performance project.
Cons
The challenges for RPE are less about the material’s performance and more about market perception and education.
Track Record
While RPE has a multi-decade track record of proven success in demanding applications like mining, agriculture, and industrial containment, it may be less familiar to engineers who have only ever specified traditional materials like clay or basic geomembranes. This means you may need to make the case for RPE by demonstrating its decades of success in equally demanding applications.
Specialized Fabrication
RPE isn’t a material you can buy in rolls at a local store and quickly piece together yourself. Because its main advantage comes from using large, custom-fabricated panels, you’ll need to work with a qualified, experienced fabricator. This ensures a high-quality product but requires planning and partnership with a reputable supplier.
Designing for a Geomembrane
Using a geomembrane effectively means taking a few specific considerations into your design and construction plan. Here are the most important principles:
Start with a Smooth Subgrade
Your liner is tough, but it’s not armor. The ground beneath it must be smooth and free of any sharp rocks, roots, or debris that could puncture it under the immense pressure of the water. A final “walk-through” to clear the site of any sharp objects before deployment is a critical, can’t-skip step.
You Must Have an Anchor Trench
You can’t just drape the liner over the top of the berms—the weight of the water will easily pull it down, and wind will displace it, so it needs to be securely locked into place. Dig a continuous trench (typically 12x12 inches or larger) a few feet back from the top edge of the slope, lay the edge of the liner in it and across the trench bottom, then backfill the trench with compacted soil to permanently anchor it.
Mind Your Slope Angles
While modern liners are strong, gentle slopes are always better than steep ones. Aim for an interior berm slope of 3:1 (horizontal:vertical) or flatter. Gentler slopes reduce stress on the liner, make installation safer for the crew, and create a more stable and usable shoreline for wildlife.
Protect the Exposed Liner
A liner is most vulnerable after it’s been installed but before it’s covered by water. Be mindful of damage from deer or other hoofed animals walking across it, and never drive equipment directly on an exposed liner. Your installation plan should include getting the liner covered with a protective soil layer or water as soon as is practical after deployment.
