Building Standards technical handbook 2017: non-domestic buildings

Silage effluent is the most prevalent cause of point source water pollution from farms in Scotland. A high proportion of serious pollution incidents occur each year through failure to contain or dispose of effluent satisfactorily.

Collection, storage and disposal of farm effluent and livestock wastes are all stages when pollution can occur. These materials are generally classified by type of stock and physical form. This may be solid, semi-solid or liquid. Solids are stored in dungsteads that must be properly drained and the effluent collected in a tank while liquids are stored in tanks above or below ground. The container must be impermeable.

The guidance to this standard should not be read in isolation. Appropriate sections of other legislation, such as the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 2003 and The Water Environment (Controlled Activities) (Scotland) Regulations 2011, as amended would also normally require to be met. The Scottish Environment Protection Agency is the body responsible for enforcing these environmental regulations and further information may be obtained from their website www.sepa.org.uk.

The Code of Good Practice for the Prevention of Environmental Pollution from Agricultural Activity is a practical guide for farmers, growers, contractors and others involved in agricultural activities, on whom there is a statutory obligation to avoid causing pollution to the environment. The Code provides helpful guidance on the planning, design, construction, management and land application of slurries and silage effluent that can give rise to pollution of water, air or soil environments. SEPA is the body responsible for enforcing these regulations.

Explanation of terms – the following terms are included to provide clarity to their meaning in the guidance to this standard.

Dungstead means a permanent storage facility for all farmyard manures including solid and semi-solid animal excreta. The construction should allow for any liquid to be contained within the store or be allowed to seep out for collection in a leak-proof storage tank.

Farm Effluent Tank means a leak-proof storage facility for liquid animal excreta (slurry), dirty water (water contaminated with slurry) and silage effluent that is of a consistency that allows it to be pumped or discharged by gravity at any stage of the handling process.

Conversions - in the case of conversions, as specified in regulation 4, the building as converted shall meet the requirement of this standard (regulation 12, schedule 6).

Every dungstead or farm effluent tank, including a slurry or silage effluent tank should be constructed in such a manner so as to prevent the escape of effluent through the structure that could cause ground contamination or environmental pollution.

The construction should also prevent seepage and overflow that might endanger any water supply or watercourse.

Every dungstead or farm effluent tank, including a slurry or silage effluent tank should be located at a distance from a premises used wholly or partly for the preparation or consumption of food so as not to prejudice the health of people in the food premises. The dungstead or farm effluent tank should be located at least 15m from the food premises.

Where there is the possibility of injury from falls, a dungstead or farm effluent tank should be covered or fenced to prevent people from falling in. Covers or fencing should be in accordance with the relevant recommendations of Section 8 of BS 5502: Part 50: 1993.