Storing slurry: slurry tank design

If you store slurry, you must follow certain regulations if your storage facilities were constructed or substantially altered after:

• 1 December 2003 in Northern Ireland
• 1 September 1991 in Scotland.

Older storage facilities are normally exempt from the regulations. However, you may have to carry out improvement work if your environmental regulator considers that your facilities could cause pollution.

You may not be able to use the structure until all necessary works are completed.

What you must do

Notify your environmental regulator in writing before you use new or substantially reconstructed or enlarged stores.

In Northern Ireland, the Northern Ireland Environment Agency (NIEA) requires at least 28 days' notice.

In Scotland, SEPA requires at least 28 days' notice.

Contact your environmental regulator

Site the slurry storage system at least 10m from any water including field drains or ditches into which slurry could enter if it were to escape.

You must construct new or substantially reconstructed or enlarged stores to last for at least 20 years with proper maintenance.

In Scotland you must not store slurry:

• within 10 metres of surface water or wetland
• within 50 metres of any spring or borehole.

SRUC: Slurry and manure

Capacity

When you add new storage or alter existing storage, you must normally provide storage capacity for:

• at least 26 weeks slurry production on farms with a pig or poultry enterprise, and 22 weeks for all other farms in Northern Ireland
• at least six months' slurry production in Scotland.

If you don't provide the required storage you must prepare a farm waste (manure) management plan.

DAERA: COGAP and farm waste management (Northern Ireland)

Scottish Government: Guidance on Farm Waste Management Plans

Ensure the reception pits and associated channels can normally hold at least two days' slurry production, including rainfall draining to the pit. If you use a sluice gate to control the flow of slurry to a reception pit, you must ensure the pit can hold the maximum quantity of slurry that can be released when the sluice is opened.

Do not overfill your slurry store. Keep the top 0.3m for above ground slurry stores and 0.75m for slurry lagoons empty.

Design and construction

Construct the base and walls of slurry tanks and any reception pits so that they can withstand the loadings specified in British Standard (BS) 5502: Part 50: 1993.

Protect the base and walls of slurry storage tanks, effluent tanks, channels, reception pits and pipes against corrosion, in accordance with (BS) 5502: Part 50: 1993.

Make the base of slurry storage tanks and the base and walls of effluent tanks, channels, reception pits and pipes impermeable, you can buy commercially available treatments for this purpose.

Extend the base of the slurry store beyond the walls and perimeter drains, and provide an effluent tank where the walls of the slurry store are not impermeable.

Provide two valves in series on any drainage pipe from the slurry tank and lock them shut when they are not in use.

Good practice

You can increase the available capacity of your slurry storage by preventing rainwater entering the system. You should:

• cover stores
• divert clean water from roofs or hard standing to discharge directly to surface water drains for treatment via sustainable drainage systems (SUDS).

Further information

The codes of good agricultural practice provide guidance on how to avoid polluting water with slurry.

In Northern Ireland, see section 2 of the DAERA code of good agricultural practice for water, air and soil.

DAERA: Code of good agricultural practice for the prevention of pollution of water, air and soil

NIEA: Silage, slurry and agricultural fuel oil information

In Scotland, see section 4 of the Prevention of Environmental Pollution from Agricultural Activity (PEPFAA) Code.

Scottish Government: Prevention of Environmental Pollution from Agricultural Activity (PEPFAA Code) 2005 (Scotland) (Adobe PDF - 1.34MB)

CIRIA: Farm waste storage - Guidelines for construction