Storage of liquid digestate

This General Binding Rule (GBR) applies to the storage of liquid digestate unless the storage is authorised by a permit or registration under these Regulations.

Authorisation level

General Binding Rule (GBR)

Rules

Storage of liquid digestate is covered by General Binding Rules. If you intend to carry out this activity, and you comply with the rules set out below, your activity will be authorised. You don’t need to apply to SEPA for an authorisation.

If you carry out an activity under this authorisation you must comply with the rules. It is an offence if you do not comply with the rules.

If you cannot comply with the rules, you will need a different type of authorisation.

General Binding Rule (GBR) for storage of liquid digestate

1. Where liquid digestate is produced on the farm, it must be stored in a liquid digestate storage system, slurry storage system or slurry bag which has sufficient capacity to accommodate the volume of liquid digestate produced during periods when application is not authorised under activity 18 of column 1 of this schedule or would not comply with the requirements of the Action Programme for Nitrate Vulnerable Zones (Scotland) Regulations 2008,

2. where liquid digestate is imported onto a farm, it must be stored in a liquid digestate storage system, slurry storage system or slurry bag which has sufficient capacity to store the quantities imported during periods when application is not authorised under activity 18 of column 1 of this schedule or would not comply with the requirements of the Action Programme for Nitrate Vulnerable Zones (Scotland) Regulations 2008,

3. in calculating the required storage capacity, the following figures must be included—

   1. the quantity of any rainfall (including any fall of snow, hail or sleet that is likely to enter the system or slurry bag (directly or indirectly) including from dungsteads, silage pits or dirty yards,
   2. the quantity of any cleaning water that is likely to enter the system or slurry bag,
   3. the quantity of any slurry from housed livestock,
   4. the likely quantity of any imported slurries and liquid digestate added to the system or slurry bag,
   5. the quantity of any liquid digestate exported off farm,

4. a liquid digestate storage system must—

   1. comply with paragraphs (e) to (k),
   2. if new (including systems constructed from used materials), or substantially reconstructed or enlarged, on or after 1 January 2022, have a life expectancy of at least 20 years, with proper maintenance, from its construction, reconstruction or enlargement,

5. the base and walls of the liquid digestate storage tank and the walls of any feedstock tank, channels and pipes must be impermeable,

6. the base and walls of the liquid digestate storage tank and feedstock tank, valves and the walls of any pipes must be protected against corrosion in accordance with paragraph 7.2 of the Code of Practice on Buildings and Structures for Agriculture published by the British Standards Institution and numbered BS 5502-50:1993+A2:2010(a), 

   (a) Publication date: 15 April 1993. ISBN 978-0-580-71245-6.

7. the base and walls of the liquid digestate storage tank and any feedstock tank must be capable of withstanding characteristic loads calculated on the assumptions and in the manner as set out in paragraph 5 of the Code of Practice on Buildings and Structures for Agriculture published by the British Standards Institution and numbered BS 5502-50:1993+A2:2010,

8. the liquid digestate storage system must not be situated within 10 metres of any surface water or opening into a surface water drain which liquid digestate could enter if it were to escape,

9. the liquid digestate tank, pipes, valves and feedstock tank must be operationally maintained to be free of any structural defects during their lifecycle,

10. where the liquid digestate storage tank is fitted with a drainage pipe—

    1. there must be two valves in series on the pipe and each valve must be capable of stopping the flow of liquid digestate through the pipe and must be kept shut and locked in that position when not in use,
    2. sub-paragraph (i) does not apply in relation to a liquid digestate storage tank which drains through the pipe into another liquid digestate storage tank of equal or greater capacity or where the tops of the tanks are at the same level,

11. where a liquid digestate storage system includes a lagoon with walls which are made of earth, the lagoon must not be filled to a level which allows less than 750 millimetres of freeboard, and in all other cases the liquid digestate storage tank must not be filled to a level which allows less than 300 millimetres of freeboard,

12. where a liquid digestate storage system constructed, or substantially reconstructed or enlarged, on or after 1 January 2022 includes a lagoon with walls which are made of earth, the lagoon must be lined with an impermeable sheet material which, with proper maintenance, liquid digestate cannot permeate for a period of at least 20 years,

13. a slurry bag may only be used to store liquid digestate if—

    1. the bag is constructed of impermeable material, is of sufficient strength and structural integrity, and is unlikely to burst or leak in its ordinary use, and
    2. it is situated in a bund which complies with the following requirements—
       1. the bund must be of at least equivalent capacity to the slurry bag,
       2. the bund must be lined with an impermeable sheet material which, with proper maintenance, liquid digestate cannot permeate for a period of at least 20 years,
       3. the bund must have a means of removing rainwater from it,
       4. other than as necessary to allow rainwater to be removed, the base and walls of the bund must not be penetrated by any valve, pipe or other opening,

14. where a liquid digestate storage system is to be constructed or to be substantially rebuilt or enlarged—

    1. the operator must give notice to SEPA of the works no later than 30 days prior to commencing the works,
    2. the notice under sub-paragraph (i) must be accompanied by an engineering plan for the works to be carried out, and
    3. the operator must retain for the lifetime of the liquid digestate storage system, for inspection by SEPA on request, the engineer’s final sign-off certificate for the works,

15. liquid digestate may be stored in a slurry storage system which complies with the requirements in column 2 of activity 32 of this schedule in relation to the storage of slurry,

    Reference to “activity 32 of this schedule” means Chapter 2, Schedule 9 of the Environmental Authorisations (Scotland) Regulations.

16. waste liquid digestate must only be stored at the place where it will be used.

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