Farm Waste Structures: Guidance on Construction, Repair and Maintenance

Chemical and pesticide stores

Note No: CGN 007, July 2000
Prepared by ADAS National Building Design Team. Funded by The Department for Environment, Food & Rural Affairs.

This leaflet is a guide to the design and construction of farm chemical stores on agricultural and horticultural premises with a storage capacity of up to 1000 litres. The information is not applicable for the storage of veterinary medicines, fertilizers, fuels and other flammable material.

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Site Suitability

  • Consult the Environment Agency and the Local Planning Authority before constructing a new store. Refer to the Water Code and Environment Agency guidelines (See References 1 & 2).
  • Avoid sites in a flood plain and with a high water table.
  • Site at least 10 metres from a water-course and 50 metres from a borehole.
  • Site more than 4 metres away from any areas that present a risk of fire including fuel stores, straw, hay and other combustible materials. Site away from sources of ignition such as domestic dwellings or grain driers.
  • Do not site cabinet stores within domestic dwellings, staff-rooms, offices or any place where food is stored.
  • Make sure that the site is accessible for the fire emergency services and that staff are aware of how to deal with a chemical spillage or fire.


  • Refer to the Green Code and the Yellow Code for information on store design (See References 3 & 4).
  • Small stores and cabinets holding less than 200 litres of chemicals should conform to BS 5502 Part 81 and Health and Safety Executive AIS notes. (See References 5 & 6).
  • Stores must be of fire resistant construction at least 30 minutes resistance for the structure including doors. Roofs should be non-combustible and fitted with smoke ventilation.
  • Build the store to conform to BS 5502 Parts 22, 23 and 81. Part 23 of BS 5502 gives information about fire precautions (See Reference 6).
  • Construct the store and adjacent areas to contain any leaks or spillage.
  • Provide an impermeable bund with a capacity of at least 110% of the total contents of the store. Increase to 185% if in a sensitive area (See References 1 & 5).
  • Do not interrupt the bund across external doorways and other openings. Provide a threshold bund. External doors should open outwards.
  • Bund or contour external areas to contain spillage where tanks are filled with chemicals.
  • Provide a below ground watertight containment tank for storage of spills when filling or washing out tanks on yard areas.
  • Make containment tanks large enough to contain the contents of the bund and contaminated wash water and rainwater.
  • Provide a canopy roof to minimise rainwater collection.
  • Provide gullies and leak-proof drainage channels to collect and convey spillage to the tank.
  • Provide a sump within the store to contain spills and wash water.
  • Ensure that materials used for construction are robust, durable and watertight.
  • Use RC 40 concrete mix to BS 5328 to build the floors. The bund walls are best built as part of the wall foundation and constructed integrally with the floor slab using RC 40 mix concrete. Engineering brickwork used for bunds should be covered with two coats of waterproof render that is resistant to attack from chemicals e.g. epoxy based cement sand.
  • Ensure that all joints in floors and walls are made watertight by using a sealant that is resistant to attack from chemicals.
  • Lay floors to a fall of 1 in 40 towards the collection sump or tank collection drainage channel.
  • Provide off-floor shelves of adequate strength to carry storage containers.

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  • Provide, adjacent to the store, a washroom with shower, washbasin and hot and cold water.
  • Provide an area of 50,000 mm2 of ventilation opening at both high and low levels, for every 20 cubic metres of store volume.
  • Provide adequate lighting within the store (See Reference 6).
  • Provide a piped water supply for wash water and for dilution. All supplies including hosepipes must be fitted with valves to prevent back siphonage.
  • Provide lockable doors.
  • Provide and fix prominently, permanent warning notices (See References 5 & 6).


  • Obtain a professional design and employ an experienced building contractor to construct the store.
  • Advice on building contracts is given in the associated leaflet No CGN 100.

Repair and maintenance


  1. The Code of Good Agricultural Practice for Water; MAFF (Free publication).
  2. Environment Agency Pollution Prevention Guidelines.
  3. Code of practice for the safe use of pesticides on farms (Green Code)MAFF Free Publication.
  4. Code of practice for suppliers of pesticides to agriculture (Yellow Code) MAFF Free Publication.
  5. Health and Safety Executive: AIS No 16, Guidance on storing pesticides.
  6. British Standard 5502: Buildings and structures for agriculture; British Standards Institution.
  7. British Standard 6213: Selection of construction sealants; British Standards Institution.

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