Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations

Applies to Scotland

Title: Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations

Category: Scotland Regulation

Date: 1991

Reference: 1991/346 (S.35) [Full text]

General Description:

These regulations have now been replaced by The Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 2001; however, it still draws on the regulations established in 1991.

These regulations set legal minimum standards for silage, slurry and agricultural fuel oil installation in Scotland. These regulations have been made under the Water Act 1980.

Within the regulation controls are established which refer to the making of silage, the storage of slurry and fuel oil on farms, exemptions to the Regulations are listed and states the required notice for the start of building works, constructions etc.. The Regulation also lays out procedures for appeals and criminal offences.

Schedule 1 - Requirements for silos.

Schedule 2 - Requirements for slurry storage systems.

Schedule 3 - Requirements for fuel oil storage areas.

The Making of Silage

Baled and wrapped or bagged silage is not normally stored within a structure but care should be taken to collect and dispose of effluent to avoid pollution. A typical silage clamp (up 1500 cubic metres in capacity) must have the following features:

  • A base which extends beyond the walls and which includes a perimeter drainage channel.
  • A tank capacity of at least 20 litres per cubic metre of silo capacity, up to 100 cubic metres, and then 6.7 litres per cubic metre of silo capacity.
  • The silo base must be impermeable, as should the tank and drains.
  • The base and walls of the silo, tank and drains should be acid resistant.
  • No part of the installation will be within 10m of a watercourse.
  • Silo walls should be designed to BS5502 part 22.
  • The installation must be built to last at least 20 years.
  • Below ground effluent tanks should also be built to last 20 years without maintenance.

Silage effluent can be 100 times more polluting than untreated sewage and so care must be taken by farmers to minimise the risk of pollution.

The Regulations state that 'no person shall have custody or control of any crop which is being made into silage unless (a) it is kept in a silo as described in schedule 1 or is an exempt structure by virtue of regulations listed in the exemptions of regulations or (b) it is compressed in the form of bales which are wrapped in an impermeable material and is stored at least 10 metres from any watercourse into which effluent from the bales could enter. Nor shall any person open a bale as described in (b) less than 10 metres from any watercourse.'

Under the 1997 revisions the SEPA were given powers to serve notice in respect of any type of structure including silage making facilities (except silo towers to BS5061), if it presents a significant risk of causing pollution. If pollution should occur there are requirements for farmers to quickly install remedial measures and costs associated with legal action and clean up can be imposed.

Field silage and making of silage in Ag-bags is allowed since the 1997 revision, but farmers must notify  SEPA at least 14 days before first using a site.   Thus nitrification requirements is also a legal requirement for any new or altered installation.

Storage of Slurry

Slurry must be stored in a slurry storage system that meets the requirements in schedule 2, summarised below, unless it is being transported in tanker in which case the tanker must not exceed 18,000 litres.

  • The tanks, drains and reception pits must all be impermeable.
  • Base, walls, reception pits and drains should be protected against corrosion as described in BS5502 : Part 50.
  • The installation should be designed to BS5502: part 50.
  • The reception pit and associated channels should hold at least 2 days slurry production.
  • Minimum installation storage capacity should be 4 months production plus allowances for rainwater, yard and parlour washings and other dirty water plus the freeboard.
  • No part of the installation will be within 10m of a watercourse.
  • The installation should have a 20 year life with routine maintenance.

Storage of Fuel oil on Farms

Fuel oil must be stored in either in a fuel storage tank within a storage area which meets the requirements in schedule 3, summarised below. These regulations do not apply if the total fuel stored is less than 1500 litres.

  • Fuel oil storage must be surrounded by a bund
  • Bund and base must be impermeable and last for 20 years with routine maintenance.
  • Every part of the store must be within the bund.
  • Taps and pipes must point downwards and be locked shut when not in use.
  • No part of the store will be within 10m of a watercourse.


A silo, slurry storage system or a fuel storage tank is exempt for the time being if either it was used before the 1st March 1991, was constructed before 1st March 1991 or the contract was entered into and construction stared before 1st March 1991 and construction was completed before 1st September 1991.

Loss of Exemption

A structure which is exempt by virtue of the exemptions above will cease to be exempt if it is substantially reconstructed or enlarged.

In 1997 the Regulations were reviewed and amended such that:

  1. regulations 3  is extended so that it applies, subject to certain exceptions, to the storage of silage and the making of field silage;
  2. the exemption conferred by regulation 7 of the 1991 Regulations (exemptions) in relation to the making of field silage is removed and the new rules in regulation 3 apply instead (except that notice need not be given to the SEPA in cases which benefited from the exemption);
  3. SEPA's power to serve an anti-pollution notice under regulation 9 of the 1991 Regulations (notice requiring work etc.) where there is a significant risk of pollution of controlled waters from slurry, fuel oil and crops being made into silage is no longer confined to the use of exempt structures and the making of field silage but applies to anyone with custody or control of those substances (or silage) in the circumstances specified in the Regulations;
  4. the period for compliance with an anti-pollution notice under regulation 9 of the 1991 Regulations is extended so that it does not expire whilst an appeal is pending even when notice of appeal is given late;
  5. the SEPA is given power to relax the requirements of Schedule 2 to the 1991 Regulations (requirements for slurry storage systems)  - 
    (i)  in relation to the minimum capacity of temporary storage facilities for slurry where a smaller capacity is adequate to avoid any significant water pollution risk;
    (ii)  in relation to the minimum distance of storage tanks, effluent tanks, channels and reception pits from inland freshwaters or coastal waters where appropriate precautions are taken to avoid any significant water pollution risk.

Pertinence to Agriculture: Agricultural Pollution, Farm Buildings, Waste, Slurry, Silage, Oil.

ADLib logo Content provided by the Agricultural Document Library
© University of Hertfordshire, 2011