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 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.

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.

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.

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.

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.

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.

Slurry bags are a less common form of storage. They can be as large as 7000 m³ and 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.