Water run-off can cause a whole host of issues for a silage pit if left unattended, so what are the signs, and methods to prevent this issue in the first place?
In this blog, we will explore the question ‘How to prevent water run-off around a silage pit’
At PPC Concrete Products, we are here to provide solutions for your construction needs, from the person working their own part-time project, to commercial clients, and everyone in-between.
What is water run-off at a silage pit?
Water run-off around a silage pit, is essentially water that has become contaminated by contact with the silage or its byproduct, silage effluent. It is a key environmental concern in agriculture and can be broken down into two main components:
1. Silage effluent
This is the most potent and polluting part of the run-off.
Effluent is a liquid that naturally seeps or leaches from the forage crop (grass, maize, etc.) as it is compacted in the silage pit. It’s an inevitable byproduct of the ensiling (fermentation) process, especially when the crop has a high moisture content.
Silage effluent is extremely aggressive and highly polluting, often cited as having a Biochemical Oxygen Demand (BOD) up to 200 times that of raw domestic sewage. If it enters a watercourse, it rapidly strips the water of oxygen, killing fish and other aquatic life.
2. Contaminated rainwater/groundwater
This is water from rain or the surrounding area that mixes with the effluent or silage material. Any rainwater that falls directly onto the uncovered silage, or onto the exposed floor area when the silage is being fed out, will become contaminated and must be treated as “ water”
Clean rainwater that falls on the yard area in front of the silage pit can mix with any escaping effluent, significantly increasing the total volume of contaminated run-off that needs to be collected and stored. Furthermore, water or surface run-off from the surrounding ground that seeps into or around the silo structure can also become contaminated.
3. The visual cues: How to spot a leak
Look for any liquid around the pit that is not clear water.
Cue | What to Look For |
Colour and streaks | Dark brown or olive-green liquid running down the side of the concrete walls or across the floor. It can look sticky or syrupy. |
Cracks and joints | Dark, wet patches, or bubbling liquid coming out of cracks in the floor or the wall/floor joint. |
Scorched plants | If the liquid hits the soil or a grassy area, it will often leave a path of dead, brown, or burnt grass because the effluent is so acidic and strong. |
Smell | A very strong, distinctive, sour, or sometimes sickly-sweet, pungent odour in the immediate area or near a ditch. |
What does contaminate water run-off do?
If run-off becomes contaminated, and isn’t contained/ disposed of accordingly, there are a number of harmful circumstances that can take place in the surrounding environment and pit itself, they are:
Environmental damage
- Kills aquatic life: As touched on previously, it is extremely polluting If it enters a watercourse, microorganisms feed on its high concentration of sugars and rapidly consume the dissolved oxygen in the water. This rapid depletion of oxygen suffocates and kills fish, plants, and other aquatic organisms, often for long distances downstream.
- Contaminates water sources: The high nutrient content (nitrogen and phosphorus) can lead to eutrophication (excessive growth of algae) in surface waters. It can also contaminate drinking water wells and groundwater.
- Acidic pollution: Its high acidity (pH typically 3.5−5) can alter soil chemistry and promote the leaching of metals into the environment.
Damage to silage pit
- Corrosion: Silage effluent is highly acidic due to the lactic and other acids produced during fermentation. This acidity makes it corrosive to steel and damages concrete surfaces, including silage pit floors, walls, collection channels, and tanks.
- Structural deterioration: The corrosion attacks the alkaline concrete, causing deterioration, cracks, and fractured joints. This makes it challenging to maintain a watertight structure, leading to leaks and the potential for environmental pollution.
How to prevent water run-off
Dealing with water run-off at a silage pit is about two simple things: making the grass drier and catching everything that leaks.
Here is a simplified guide on how to stop the liquid (effluent) from escaping
1. Stop the water before It starts (Prevention)
The effluent is just water squeezed out of the grass. Less water in the grass means less leakage later.
Action | Why It Works |
Wilt the grass | This is the most important step. After cutting the grass, let it dry in the field for about 12 to 24 hours. This gets the moisture level down to your target. If the grass is dry enough, it produces almost no effluent. |
Cover well | When the pit is finished, make sure the plastic cover sticks out far past the walls and drainage channels. This sends clean rainwater away from the pit, so it doesn’t mix with and increase the amount of contaminated effluent you have to collect. |
Consider a roof | A roof keeps all rain off the pit, which is the easiest way to prevent clean water from turning into contaminated effluent when the pit is open for feeding. |
2. Catch what leaks (Containment)
You must be ready to catch any liquid that the grass still produces.
Your pit must be built on a leak-proof concrete floor that won’t crack or let liquid seep through. It must be supported through the floor, which should contain channels (like gutters) around the edges. These are the main system for collecting the liquid.
Once collected, all the channels must drain into a specially built, leak-proof collection tank. You must check this tank daily for the first week or two and empty it before it overflows.
Can interlocking concrete blocks help against water run off?
The short answer is yes, they are very helpful for constructing the walls of a robust silage pit, but they are not the sole solution for preventing leakage. Interlocking concrete blocks, are a popular choice for silage pit construction because of their strength and flexibility.
How ICB’s help
- Structural strength: The blocks interlock to create very strong and secure walls that can withstand the immense outward pressure exerted by the compacted silage. This minimises the risk of wall collapse or bulging.
- Durability: Concrete is resistant to the corrosive silage acid and harsh weather, leading to a long lifespan with minimal maintenance.
- Flexibility: They are quick to install, can be easily reconfigured or expanded, and require less time than poured concrete walls, which require curing and setting once poured.
By securing a consultation with a service like PPC concrete products, you can rest assured that your silage pit will have the best resources possible, ensuring a reliable, durable, long-lasting silage pit.
PPC concrete products for silage pits and more
As an established supplier all over the UK, PPC Concrete Products is always happy to help, which is why we encourage you to get in touch with any questions you may have or have a look at our FAQ.
In this blog, we hope to have shown you how to prevent water run-off around a silage pit.
Take a read of our case studies to truly understand how we have provided solutions for business in the past with the use of our interlocking concrete blocks, and ultimately, how we can help you today.
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