Building a successful fish hatchery is a complex undertaking, and getting your pond liner right is probably the most important part. Whether you’re using above-ground tanks and raceways or building in-ground ponds, a well-installed geomembrane liner is essential for keeping the water where it belongs, maintaining healthy conditions, and protecting your investment.
While in-ground and above-ground systems each have their quirks, this chapter focuses on the core principles of geomembrane liner installation that apply to both. We’ll walk through the key steps – from prepping the site to seaming and anchoring – to set you up for a long-lasting and effective lining solution.
Try This: Before you start, familiarize yourself with the liner manufacturer’s instructions for a straightforward, error-free installation.
Essential Pre-Installation Steps (Common to All)
Before you even unroll your geomembrane liner, start with a few preliminary (but critical) steps to ensure a successful installation.
Subgrade/Substrate Preparation
Whether it’s the soil at the bottom of an in-ground pond or the interior surface of an above-ground tank, the surface that your liner rests on needs to be:
Smooth: Sharp rocks, roots, debris, or protrusions can puncture or damage the liner.
Stable: Let’s face it: thousands of gallons of water make for a pretty heavy load! The surface of your site must be stable and solid enough to support the weight without settling or shifting. A concrete pad is a good idea, but carefully compacted soil can work just as well.
Clean: The area should be free of any contaminants that could react with or degrade the liner. If in doubt, conduct a few soil tests, particularly if your land is near a former industrial or mine site.
For In-Ground Ponds
- Be attentive in locating and removing all rocks, roots, and sharp objects, even if they’re mostly buried.
- Grade and compact the soil to create a smooth, even surface.
- Consider using a geotextile underlayment for added protection, especially in areas with rocky soil.
For Above-Ground Ponds
- Ensure the tank’s interior surface is smooth and free of rough edges or weld points.
- Carefully clean the surface to remove any dirt, oil, or debris. Some geomembranes are sensitive to hydrocarbons, so pay particular attention to oil and grease.
Liner Handling and Storage
While reinforced geomembrane liners are pretty durable, they can be damaged if not handled and stored correctly before installation.
Preventing Damage
Avoid dragging the liner over rough surfaces or dropping heavy objects on it.
Proper Folding and Rolling
Follow the manufacturer’s instructions for folding and rolling the liner to avoid creases or stress points.
UV Protection
Store the liner in a shaded area or cover it with a tarp to protect it from prolonged sunlight exposure, which can degrade some materials.
Extreme Temperatures
Avoid storing the liner in very hot or extremely cold temperatures, as this can sometimes affect its flexibility and workability.
Try This: Upon delivery, carefully inspect the liner for any signs of damage and follow the manufacturer’s guidelines for on-site storage.
Tools and Equipment
Having the right tools and equipment on hand will make the installation process much smoother and more efficient.
Measuring Tools
Accurate measuring tapes and other tools are essential for precise liner placement and cutting.
Cutting Tools
Sharp utility knives or specialized liner cutters are needed for trimming the liner, especially for thick or reinforced geomembranes.
Seaming Equipment
If on-site seaming is required, you’ll need the appropriate welding equipment (for polyethylene liners) or adhesive applicators (for EPDM liners).
Anchoring Tools
Power tools for creating anchor trenches (for in-ground ponds) or attaching the liner to tank walls (for above-ground ponds) will speed up installation and ensure secure attachments.
Safety Equipment
Wear appropriate safety gear, such as gloves, safety glasses, and sturdy footwear.
Try This:
- Work with your supplier to establish what cutting and seaming may be needed at installation. A custom-fabricated liner will minimize this, but pipe boots and other perforations still need to be handled on-site.
- Before starting the installation, create a checklist of all necessary tools and equipment to avoid delays and ensure you have everything you need.
Liner Installation Techniques (Common Principles)
Once your site is prepped and your liner is on-site, it’s time for the main event: installation. While in-ground and above-ground ponds have slightly different approaches, the core techniques for handling and securing the geomembrane liner are the same.
Deploying the Liner
Start by getting the liner into the correct position.
- Unfold or unroll the liner according to the layout instructions provided by your supplier, avoiding sharp folds or creases that could weaken the material.
- Try to smooth out any wrinkles as you unroll it. Small wrinkles are relatively harmless, but large ones can create stress points.
- Don’t stretch it too tightly. Geomembranes expand and contract with temperature changes and may shift with ground movement, so allow some slack.
Try This: Work with a team to carefully position the liner, especially for larger ponds. Moving a large liner that’s askew can be a lot of work and risks damaging it.
Seaming and Sealing
For large ponds, multiple liner panels may need to be seamed together on-site (these are referred to as field seams). Pipes and other liner penetrations also require durable, high-quality seams to prevent leaks.
- Ensure panels, pipe boots, and other sealing tools have adequate overlap, as specified by the manufacturer (typically 4-6 inches).
- Make sure the liner surfaces to be seamed are clean and dry.
- Adhesives (for EPDM) require consistent pressure across the entire overlap to eliminate air bubbles for a strong, waterproof seam.
- For welded seams (for polyethylene), maintain a consistent speed and temperature to create a strong, continuous seam.
- Always test your seams for integrity, following the manufacturer’s recommended procedures. This might involve air pressure testing or destructive testing on a small sample.
Try This: If you’re new to geomembrane seaming, practice on scrap material first to get a feel for the technique.
Anchoring and Termination
When in service, a liner must remain in place, no matter what’s happening around it. Anchor it securely at the pond edges or along the tank walls to prevent it from slipping or being pulled out.
- Use the recommended anchoring method for your pond type (anchor trenches for in-ground, mechanical fasteners, or adhesives for above-ground).
- Ensure the anchor is continuous and uninterrupted around the entire perimeter of the pond to avoid uneven stress on the liner material.
- Don’t pull the liner too tight during anchoring—it needs a small amount of flexibility to handle water movement and thermal changes.
Try This: Pay close attention to corners and other areas where the liner may be stressed. These are often the weakest points in the system, and a little bit of extra slack can make a big difference.
Specific Considerations
While we’ve outlined the core principles of geomembrane liner installation that apply to in-ground and above-ground ponds, their configurations are unique and have different requirements.
In-Ground Ponds
In-ground ponds present unique challenges related to excavation, soil conditions, and potential groundwater issues. Proper site preparation, including grading, compaction, and potentially using a geotextile underlayment, is especially important. Anchor trenches dug around the pond’s perimeter are usually the preferred anchoring technique.
Try This: For detailed, step-by-step guidance on in-ground pond liner installation, please refer to our comprehensive guide: Pond Liners: The Complete Guide.
Above-Ground Ponds
Above-ground ponds are generally simpler to deal with when it comes to liner installation. Since they’re usually built from prefabricated tanks or raceways, the primary focus is ensuring a smooth, clean interior surface for the liner to rest against. The liner is generally attached directly to the tank walls with mechanical fasteners or adhesives.
