How To Use Geofabric in and Around Your Dam

It’s easier than ever to install your very own pond in your backyard. And it’s all thanks to new technology. But you still need to be careful about it; research is vital. You need to know how to prevent erosion, protect the environment, and prevent moisture loss. There’s so much to consider! Luckily, geofabric can make this job easier, even if it’s just a little bit.

So, what’s geotextile fabric all about?

What Is Geofabric and What Is It Used for?

Geotextile fabrics, or geofabrics, are a type of material. They’re permeable fabrics used for a variety of activities concerning soil and agriculture.

Whenever soil is exposed, it’s at risk of erosion due to rainwater and wind, or any other elements. This is part of the problem of building a dam. While it looks pretty, it can quickly damage the environment due to the water on top of the soil.

Geotextiles are here to prevent this. Typically, they’re made using polyester and polypropylene. They can be woven or non-woven, made into staple fibre (short fibres locked together through needling) or a continuous filament (long, continuous strands of thread).

Geofabric is naturally porous, so it’s not the same as a pond liner. However, it has a variety of uses including reinforcement, filtration, separation, sealing, and preventing erosion.

1. Separation

The ground rarely has the same type of soil throughout. When there are multiple types, agriculturists can install geogabric between the two to separate them.

This has a range of uses, including road construction. It makes it easy to keep fine subgrade aggregates away from the top layer of coarse aggregates. This is important to maintain proper drainage in the soil, because it stops the delicate aggregate from filling the gaps between the coarser stuff.

2. Reinforcement

Geofabric can also reinforce the soil, which is important for erosion control but also several other applications. For example, it can help with:

• Supporting loads
• Bearing failure plane alterations
• Restraints that restrict movement

These applications are useful for dams, where soil erosion can be a problem.

3. Filtration

You can also use geofabric to create a filtration layer. The highly porous nature of geotextiles allows water flow in both directions, and the right fabrics also help with soil retention. As a result, they’re ideal for use in filtration because they prevent fine aggregates from getting between the layers of the soil.

What’s more, they can contribute to effective filtration by dissipating kinetic energy from the rise in capillary pressure of the groundwater. As a result, geofabric promotes water flow lateral to the surface.

It’s important to choose the right drainage geotextiles for this use, though, if you want to reap the maximum benefits from the product.

4. Sealing

Some geofabric can be reinforced with asphalt or another material to make it waterproof. This restricts the flow of liquids in both directions.

By the way, for this to work, you’ll need nonwoven geotextiles. The fabric can prevent water loss due to contamination and evaporation, or stop pollutants from entering the groundwater.

5. Soil Protection

Perhaps most importantly, geotextiles are a cost effective form of erosion control. Groundwater and other water flow can erode soils, but geofabrics can provide a barrier that prevents this, and prevents fine materials from leaching.

In some cases, you can place geofabric at the bottom of a dam, underwater, to prevent the erosion of soft soils on the bed. With waterproof geotextiles, you can even protect the soils beneath your pond lining, allowing water to remain safely in your dam at all times.

Woven vs. Non-Woven Geotextiles

The two types of geo fabric have different applications.

Woven geo fabric has a high tensile and load capacity. It has a lot of landscaping applications, including use in retaining walls.

Nonwoven geotextiles have even wider common applications. They’re ideal for stabilisation, reinforcement, and subsoil drainage. They can be highly porous or semi-permeable, which means they have a wider range of applications as natural filters. But woven geo fabric has a low flow-through rate, which means it’s less useful for things like soil migration.

Using Geotextiles for Your Dam

If you want to use geotextiles in your dam, you’re in luck. They make a great, cost-effective underlay to go beneath your pond liner. They also are a great way to install a dam in agriculture, controlling the flow of water.

However, you need to know how to install it properly.

1. Location: Choose a dam where geofabrics will actually be useful, such as areas with soft soil or suitable ground. If you’re trying to seal water in, you’ll need to work with the natural conditions of the land, not against them. Be careful not to block any drainage points with your fabric, including roadside drains or your neighbour’s drain.
2. Notching: Cut a notch into the bank on each side of the dam, approximately 10-15cm. This is where the fence posts will go.
3. Fencing: Install fence posts vertically into the notches, tight to the bank.
4. Wiring: Cut wire fencing approximately 20-30cm wider than the distance between the installed posts, and 10cm longer than the desired height of the dam. Staple the wire securely to the upstream side of the posts, leaving an equal length on each side. Fold the 10cm excess along the bed of the watercourse toward the upstream of the dam. No water should be able to flow between the bank and the posts, or this will cause instability.
5. Adding geofabric: Cut the fabric to the same width as the wire fencing, but with an extra 50cm-1m. Fix this to the wire by folding approximately 2cm over the top and fixing it in place with wire fasteners or small cable ties. Again, leave equal excess on each side.
6. Centre notch: Make a cut in the geofabric, creating a notch that is the same depth as one square of the wire fencing, and 1-2 squares wide. Fold the material around the wire and fasten it securely.
7. Sealing: Press the excess wire and geotextile into the bed and banks using a spade. Weigh it down with large stones. You should be able to spot any leaks; seal them where possible. Finally, add some boulders downstream from the dam to prevent the scouring of the bed.

When your dam is complete, you should inspect it regularly to ensure it’s intact.

Geofabric FAQs

Here are some common questions about geofabric.

1. Can water pass through geofabric?

Yes. Depending on the type of fabric, water can pass through, but other fine particles and soils cannot. This is why they are a great option for filtration. Note, however, that some geofabrics can be reinforced to be waterproof.

2. Does geofabric stop weeds?

No. Geotextiles slow down and prevent the growth of weeds, but they cannot stop them entirely. Weeds can still grow on top if animals or wind drops seeds onto the membrane.

3. How long does geofabric last?

Geofabric generally lasts much longer than polypropylene and other materials, with the fibre lasting over 50 years. However, even synthetic geotextiles can last around 20 years with the proper care and maintenance.