Perth is famous for its beautiful sandy soil, but what is great for the beach can be a nightmare for your underground infrastructure. During heavy rain, urban runoff carries fine silica sand and silt directly into your drainage system. When this mixture enters a storage tank, it doesn’t just sit there—it turns into a liquid sandpaper that can grind away at your concrete and destroy your pumps.
If you are managing a property in Western Australia, understanding how to deal with this “abrasive erosion” is the key to avoiding a total system collapse.
The “Sand-Paper Effect” on Concrete
Most people think of concrete as an indestructible material, but it is actually quite porous. When storm water rushes into a tank, it carries heavy loads of sediment. As the water swirls around, the sand grains rub against the walls and floor with immense pressure.
This leads to abrasion damage, where the smooth protective surface of the concrete is literally sanded away. Over time, this exposes the aggregate (the stones inside the concrete) and can even lead to concrete carbonation. This is a chemical change that makes the concrete weaker and can cause the steel reinforcement inside the walls to rust. If you see “bumpy” or sandy-feeling walls inside your tank, it is a sign that you need a professional assessment.
Why Silt Pits are Your First Line of Defence
The best way to stop sand from damaging your tank is to catch it before it even gets there. This is why most Perth systems use a silt pit. Think of a silt pit as a “trap” where the water slows down so the heavy sand can sink to the bottom while the cleaner water flows into the main tank.
However, a silt pit only works if it has space. If it is full of mud, the sand will simply sail straight over the top and into your storage tank. This is why pump maintenance perth must always include a thorough inspection and cleaning of these pits. By using silt pit vacuuming to remove the buildup, you stop the abrasive cycle before it starts.
High-Tech Repairs with High-Strength Epoxies
When a tank has already suffered from scouring and erosion, a simple cement patch won’t last long. The new surface needs to be even tougher than the original concrete to survive the next storm.
For modern storm water tank repairs perth, we use specialised high-strength epoxies and resin-modified mortars. These materials are designed for “structural patching.” They bond incredibly tightly to the old concrete and create a glass-hard surface that resists abrasion. These epoxies are also waterproof, meaning they stop any leaks while simultaneously reinforcing the structure of the tank.
Protecting Your Pumps from Impeller Scouring
It isn’t just the tank walls that suffer. The pumps sitting at the bottom of your storm water system are extremely sensitive to sand. When a pump sucks up silty water, the sand grains hit the spinning internal blades—known as the impeller—at high speeds.
This causes impeller scouring, where the sharp edges of the blades are rounded off and eaten away. A scoured pump has to work twice as hard to move the same amount of water, which leads to higher power bills and eventual motor failure. Regular water tank repair perth and cleaning ensure that your pumps are only moving water, not liquid sandpaper.
The Solution: A Proactive Maintenance Plan
Dealing with storm water in Perth is a constant battle against the elements. The most cost-effective way to manage your assets is to combine regular cleaning with technical repairs.
A standard maintenance visit should involve:
- Silt Pit Vacuuming: Removing the accumulated sand from the entry points.
- Tank Cleaning: Clearing the sludge from the floor of the main tank.
- Surface Inspection: Checking for signs of abrasion or exposed aggregate.
- Pump Health Check: Ensuring the impellers aren’t being ground down by sediment.
If your property has been through a few heavy winters without a check-up, it is time to look at the health of your storm water system.
For property owners and managers looking for reliable drainage solutions, PMP Fire Services provides the expert maintenance and repair work needed to protect your underground assets.
Frequently Asked Questions
How do I know if my storm water tank is damaged by silt?
The most common signs are “dirty” water overflowing from the system, the pump running longer than usual, or visible sand and grit at the bottom of the tank. A professional inspection can confirm if the concrete walls are thinning.
Can you repair a tank without digging it up?
Yes. Most storm water tank repairs perth are done from the inside using “trenchless” methods. This means we can clean, patch, and seal the tank through the existing manhole or access hatch.
Why is Perth sand worse for tanks than clay?
Perth’s “Spearwood” or “Bassendean” sands are made of silica, which is very hard and sharp. Clay is much softer and tends to clog things, whereas sand acts as an abrasive that wears away metal and concrete.
How often should silt pits be vacuumed?
Ideally, you should have your silt pits cleaned at least once a year, usually in autumn before the heavy winter rains arrive. If your property is near a construction site or has lots of open garden areas, you may need it twice a year.
Is the epoxy used in repairs safe for the environment?
The industrial epoxies used for water tank repair perth are “solvent-free” once cured. This means they don’t leach chemicals into the storm water system and are safe for the surrounding soil and groundwater.