Different types of slurry stores

There are several slurry storage options available, all of which have their pros and cons.

See below for some of the different options available. More detailed information can be found in the Construction Industry Research and Information Association (CIRIA) guide to Livestock manure and silage storage infrastructure for agriculture.

Earth-banked lagoons

Earth-banked lagoons can be a cost-effective way of storing slurry but are only appropriate to construct in sufficiently impermeable soil. This means that permeability does not exceed 10^-9m/s, typically with a clay content of 20–30% and with sufficient material to ensure there is an impermeable layer at least 1 m thick. Soils can be lab-tested to determine permeability. It requires a 750 mm freeboard.

Earth-banked slurry lagoon. Copyright AHDB.

Positives and negatives of earth-banked lagoons

Positives	Negatives
Cheapest form of storage to construct	Surface to volume ratio is high, so it will collect a lot of rainwater
Simple approach	Large lagoons can be difficult to agitate, making it hard to present slurry in a suitable condition for spreading
Versatile – easily extended, capable of storing slurries of different DM content	Occupies large land area
Repair and maintenance is inexpensive	Requires suitable soil type and low water table
Structure life will easily exceed 20 years if maintained properly	Vulnerable to damage by vegetation and burrowing mammals
	Machinery operation can damage lagoon’s structural integrity
	Leak detection systems are difficult to fit and often unsatisfactory
	Difficult to cover with impermeable material

Lined earth-banked lagoons

Lined lagoons function like an earth-banked lagoon but can be used where the permeability requirements (for earth banked lagoons) cannot be met. A synthetic sheet, secondary liner or imported clay interior liner can be used within an earth-banked lagoon to make a lined lagoon. It requires a 750 mm freeboard.

Lined earth-banked lagoon. Copyright AHDB.

Positives and negatives of of lined earth-banked lagoons

Positives	Negatives
Relatively cheap form of storage compared to concrete or steel	Surface-to-volume ratio is high, so it will collect a lot of rainwater
Liner allows storage in permeable soils	Large lagoons can be difficult to agitate, making it hard to present slurry in a suitable condition for spreading
Liner can be combined with access ramps and concrete flooring, which increases the range of material that can be stored	Occupies large land area
	Liner is vulnerable to damage, especially when emptying
	Synthetic liners will have a limited lifespan
	Vulnerable to damage by vegetation and burrowing mammals
	Machinery can damage lagoon’s structural integrity
	Leak detection systems needed
	Unsuitable for areas with high water table as liner will float on groundwater

Above-ground tanks

An above-ground tank can be used in areas where a lagoon may not be appropriate such as where land may have a high-water table or where the land availability is limited. This option is more expensive than earth-banked lagoons.

Above-ground tanks will usually require a reception pit where the slurry can be scraped to a transfer pump to mix and lift the slurry into the store.

Above ground slurry tank. Copyright AHDB.

Positives and negatives of above-ground tanks

Positives	Negatives
They are tall structures with minimal land take, so there is less surface area to collect rainfall, lowering spreading costs and capacity requirements	Reliant on pumps so not suitable for manures with high dry matter content
Depending on structural requirements, they can be fairly simple to extend. This will increase capacity without increasing footprint	Complex pumping system will increase the possibility of mechanical failure
Relatively inexpensive and simple to cover	Costs more than earth-banked lagoons
Suitable for high water table areas	No safe access inside so unsuitable for bedding that settles
Regular maintenance is inexpensive	Synthetic liners will have a limited lifespan
Periodic refurbishment such as resealing, re-bolting or replacement of panels is possible	Danger of impact damage

Concrete stores

Concrete stores are constructed from reinforced concrete panels or mass-poured. These types of stores can be constructed above or below ground level, and filling can be done by pump, gravity discharge or mechanical scraper.

Positives and negatives of concrete stores

Positives	Negatives
They are tall structures with minimal land take, so there is less surface area to collect rainfall, lowering spreading costs and capacity requirements	Reliant on pumps so not suitable for manures with high dry matter content
Depending on structural requirements, they can be fairly simple to extend. This will increase capacity without increasing footprint	Complex pumping system will increase the possibility of mechanical failure
Relatively inexpensive and simple to cover	Costs more than earth-banked lagoons
Suitable for high water table areas	No safe access inside so unsuitable for bedding that settles
Regular maintenance is inexpensive	Synthetic liners will have a limited lifespan
Periodic refurbishment such as resealing, re-bolting or replacement of panels is possible	Danger of impact damage

Underfloor slatted stores

An underfloor slatted store will sit underneath part of the housed livestock building. This is typically in areas where the livestock circulate or under feeding areas. It will usually only receive the manure from the housed livestock and little to no rainfall. It is typically constructed with poured concrete to minimise the risk of leakage. The design requires a minimum of 300 mm freeboard.

Positives and negatives of underfloor slatted stores

Positives	Negatives
Usually underground but can be above natural ground level	May require access to remove solids
Periodically emptied by pump	There will be health and safety issues if entering an enclosed store
Little maintenance needed
Range of construction materials available
Suitable for most bedding types except chopped straw and sand

Weeping wall stores

Weeping wall storage provides separation of slurries as well as storage. It typically consists of a concrete floor with one or more semi-permeable walls. The walls allow the liquid part of the slurry to drain out and be collected into an additional store. The retained solids can be removed via a ramp, lift out panels or excavator. The liquid collected from the weeping wall is classified as slurry and is subject to standard regulations and requirements.

Positives and negatives of weeping wall stores

Positives	Negatives
Size and shape can be designed to suit site layout	Suitable for only a limited range of slurry DM types
Separates slurry into pumpable liquid and semi-solid manure for ease of spreading	Construction cost is high
Covering is possible with ease depending on size and shape	Repairs to concrete panels can be expensive
Maintenance costs are generally low
Generally hardwearing, moderately vulnerable to damage
Not dependent on soil type or water table
Store is long lasting providing panels do not get damaged

Slurry bags

Slurry bags are a less common form of storage. They can be as large as 7000 m³and are constructed with reinforced impermeable artificial membranes such as PVC. They can be fitted with several inlets to facilitate emptying and filling. They can also incorporate electric or hydraulic agitators. They are only suitable for slurries that are pumpable but are highly effective at capturing and containing ammonia emissions.

Positives and negatives of slurry bags

Positives	Negatives
Similar cost to concrete or steel storage	May need additional support structure or secondary containment (such as a lined lagoon)
Highly effective at stopping nitrogen loss in the form of ammonia emissions	A leak detection system will likely be required
Possible to incorporate stirrers	Synthetic liner has a limited lifespan (around 20 years) and can be damaged by exposure to light and extreme temperature
Excludes rainwater	Only suitable for pumpable slurries (solid-free)
Minimal maintenance required	Moderate to high land take
	Less suitable for areas with a high water table
	Bunding required in case of split
	Vulnerable to damage by mammals, so must be fenced off from livestock

Topics:

Storage

Sectors:

Beef & Lamb Dairy Pork

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store slurry storage