These guidelines have been drawn up to assist all who design and operate dairies and other milk and milk product handling operations in the avoidance of water pollution and the minimisation of waste. They should be read with the Agencies' general
guidance on preventing pollution on industrial sites (PPG11). They have been produced by the Environment Agency for England and Wales, the Scottish Environment Protection Agency and the Environment and Heritage Service in Northern Ireland, referred to as the Agency or the Agencies. Every site is different and will need to be considered accordingly. If a new operation or major alterations are planned, early consultation with the Agency is advisable. Contact details will be found at the end of these guidelines.
These guidelines focus on pollution risks which are specific to the dairy industry. They supplement the general guidance provided in the Agencies' document "Preventing pollution on industrial sites" (PPG11 -Reference 1) and should, therefore, be read in conjunction with it. They are not intended for small scale, farm based operations, although much of the content will be relevant. In addition to the existing legislation which applies to industrial sites, milk handling facilities producing more than 200 tonnes per day will come under the Integrated Pollution Prevention and Control regime as from 31st October 1999.
2. POLLUTING POTENTIAL OF DAIRY OPERATIONS
a. Milk and milk products
It is not often recognised that milk can have a significant polluting effect on water if allowed to reach rivers or streams. It can be as much as 400 times more polluting than untreated domestic sewage. Naturally occurring bacteria break down milk entering a watercourse, using up oxygen in the water more quickly than it can be replaced. As a result of falling oxygen levels, fish and other creatures can suffocate. The high fat content of milk and its products can also cause physical problems within drainage systems. Solidified fat can cause blockages, resulting in overflows from the system and possible pollution of watercourses.
b. Chemicals and cleaners
Sodium hydroxide (caustic soda), disinfectants, acids and cleaning agents all have the potential to cause serious pollution and to impair effluent treatment. In addition, cooling and refrigeration systems often contain ammonia or biocides which can be damaging to the water environment.
c. Fruit juices
Fruit juices, particularly when handled as concentrates, may have the same de-oxygenating effect on a watercourse as milk. In addition they are often highly acidic and may also contain preservatives.
3. SITE DRAINAGE
a. Surface water drainage
It should be remembered that surface water drainage discharges to a watercourse, which may be remote from the site, or to water contained in underground strata (groundwater) via a soakaway.
Surface water should therefore be clean and uncontaminated. The spillage of milk products in yard areas connected to the surface water drain will result in pollution. Devices used to measure pH, turbidity
or conductivity can be used to continuously monitor the quality of surface water in the system and trigger alarms. However, these are not a substitute for sound practices which will avoid spillages in the
first place and should not be relied upon as the sole means of preventing pollution.
b. Trade effluent discharges to the foul sewer
Discharges of waste water should pass to the public foul sewer if available, or be treated, subject to the agreement of the sewerage undertaker. In most cases, a trade effluent consent will be required.
Sewerage undertakers will normally wish to minimise the amount of rainwater entering the foul sewer and it may be necessary to provide a roof for loading bays, cleaning areas and waste compactors. Due
to the high organic content of dairy effluents, discharges to sewer must be carefully controlled to prevent overloading of the sewage treatment plant. Trade effluent staff from the local sewerage
undertaker should be able to give further, site-specific, advice.
c. Discharges to controlled waters
Where no public foul sewer is available, the site will require effluent treatment facilities designed to deal with the anticipated strength, nature and volume of waste water generated from all site operations.
Treatment plants must be closely monitored by a suitably qualified person and it is essential that maintenance is carried out regularly. Alarms should be provided to alert staff to plant failures.
The treatment required may include fat removal, flow and load balancing, biological treatment and pH correction. An Agency consent is required for any discharge of trade effluent into a controlled water
(which includes all watercourses, lakes, lochs, coastal waters and groundwaters) and may also be required for discharges into or onto land. Such consents set out the quality and quantity of effluent
that may be discharged. They are not granted automatically, and early consultation with the Agency is advised before any discharge is considered.
In some situations, an alternative to on site treatment may be to drain designated areas to a sealed tank for off site disposal by a licensed waste disposal contractor.
d. Drainage systems
A high proportion of water pollution incidents from dairies occur as a result of problems with the site drainage system. These arise as a result of damage to the fabric of the drains, blockage due to fat accumulation or solid debris, wrong connections and failure of pumping systems. It is therefore vital that there is a clear management responsibility for site drainage and that adequate, up-to-date records are maintained. A regular programme of inspection and maintenance should be undertaken. Daily visual inspection of surface water drains at key points is a simple way to assess their condition and quickly identify faults.
Cleaning materials used in dairies are highly corrosive and drains must be constructed using suitably resistant materials.
Waste-water drainage systems should be equipped with appropriately designed grease traps and gratings to prevent sewer blockages. It is particularly important that these are regularly inspected,
emptied and maintained, with cleaning taking place in an area draining to the foul sewer.
Gullies, grids and manhole covers should be identified as foul or surface systems using colour coded arrows indicating the direction of flow. Use blue for surface water, red for foul drains and ensure these are understood by staff.
Care should be taken to ensure that all drainage from welfare facilities such as toilets, sinks, showers and canteens is correctly connected into the site's foul drainage system. Such connections may require approval from the sewerage undertaker.
e. Pre-treatment, flow and load balancing
Pre-treatment and flow and load balancing may be required whether foul drainage passes to on site treatment facilities or the public foul sewer. Sudden changes in volume and composition can affect the efficiency of a treatment plant and are likely to have a detrimental effect on the quality of effluent discharged. Pre-treatment will reduce the strength of the effluent passed forward for treatment and on-line balancing tanks will deal with normal daily fluctuations. An off-line tank may be used as a holding or dump tank in emergencies. pH, conductivity or turbidity measuring devices in the drainage system can be used to automatically divert effluent to such a tank.
f. Discharges from plant rooms, air conditioning and heating systems and chillers
Under no circumstances should chemically treated water or condensate from any refrigeration, air conditioning or heating system be discharged into the surface water system. Particular care should be taken that discharges at roof level do not enter the surface water system via down pipes. Such waste waters should be discharged to the foul drainage system or collected and disposed of by a registered waste disposal contractor. Internal floor drainage systems for associated plant, chemical storage or dosing areas must not be connected to surface water drains.
4. CLEANING ACTIVITIES
Large volumes of polluted water are produced in cleaning operations in dairies. All cleaning agents are potentially polluting and cleaning effluents must not be allowed to enter surface water drainage systems or soakaways. This is also the case for effluent arising from the use of pressure or steam cleaners. Guidance on these is available (PPG13 -Reference 2). In certain environmentally sensitive areas, phosphorous free detergents should be used.
a. Process area cleaning
Waste waters from cleaning activities are polluting and must be discharged to the site's foul drainage system at a designated location. Ensure all staff and contractors working on site are aware of the disposal facilities for wash waters, and that surface water gullies should not be used for the disposal of wastes, by using clear signs.
b. Equipment and vehicle cleaning
A designated and clearly marked washbay, discharging to the site foul drainage system, should be provided for the cleaning of dairy equipment and utensils. Similar facilities should be provided for any vehicle washing. Vehicle wash recycling systems are available.
c. Cleaning of loading and parking areas
The cleaning of yard and parking areas is not encouraged by the Agencies. Cleaning should not be carried out unless the effluent generated can be contained by isolating the area from the surface water drainage system. Such waste waters must be discharged to the foul drainage system or collected for disposal by a licensed waste disposal contractor.
d. Roof areas
Waste water produced when cleaning roofs should be collected for treatment. Care should be taken that it is not allowed to discharge to the surface water system via roofwater down pipes. Roofs in the proximity of spray driers must drain into the site's foul drainage system.
5. DELIVERY AND HANDLING OF MATERIALS
a. Loading and unloading areas
The risk of spillage and pollution is high in these areas and they should, therefore, be connected to the foul sewer and clearly marked. They should be isolated from the surface water system. This may be achieved using bunding in the form of "roll over" bunds, ramps or stepped access.
All deliveries of milk, oil and potentially polluting materials such as chemicals and cleaners must be supervised by a responsible person. Tankers should discharge via a lockable fixed coupling within a bunded area. If a spillage does occur, it should be contained and reported immediately. DO NOT HOSE IT DOWN.
Where possible pipelines should be sited above ground and protected from collision damage. If a pipeline is to be installed underground, it should be placed in a leak-tight protective sleeve or duct and subject to regular inspection and testing. Pipeline ducts should not be connected to the surface water drainage system.
6. STORAGE AND PLANT FACILITIES
a. Above ground storage
All above ground storage tanks, drums and containers, including those containing fruit juice, should be sited on an impermeable base within a bund. Particular care is needed for Intermediate Bulk Containers (IBCs) containing chemicals such as hypochlorite or acid. The bund should consist of a base and surrounding walls which must be constructed or lined with a material impermeable to the liquid stored and designed to contain a minimum of 110% of the tank capacity. Pipework should be constructed to pass over the bund rather than through it. Tanks should be clearly marked with their contents and volume. An eye glass or gauge should be fitted to indicate volume and prevent overfilling. Detailed guidelines on oil storage are available (PPG2 -Reference 3). Storage of potentially polluting liquids at or above roof level should be avoided.
b. Milk silos
Milk silo areas should either be bunded as above or drained to the foul drainage system. The latter should only be adopted if holding or dump tanks are available to prevent overloading of downstream treatment facilities.
c. Boiler house
Boiler house sumps should have high level alarms and should not be connected to the surface water system. Automatic pumps should not be used.
d. Refrigeration and air conditioning plant
Refrigeration and air conditioning units often contain CFC coolants which must not be released to the atmosphere. Maintenance and repairs should be undertaken by a specialist contractor equipped to deal with these.
7. WASTE MANAGEMENT
Waste management is a complex area of legislation which the Agencies are responsible for implementing. In addition to the guidance in PPG11, the following areas are particularly relevant to the dairy industry.
E M E R G E N C Y HOT L I N E
0800 80 70 60
The 24-hour emergency hotline number for reporting all environmental incidents relating to air, land and water in England, Wales, Scotland and Northern Ireland.
ENVIRONMENT & HERITAGE SERVICE SCOTTISH ENVIRONMENT
Peterborough PE2 5ZR
Tel: 01733 371 811
Fax: 01733 231 840
550 Streetsbrook Road
Solihull B91 1QT
Tel: 0121 711 2324
Fax: 0121 711 5824
21 Park Square South
Leeds LS1 2QG
Tel: 0113 244 0191
Fax: 0113 246 1889
Richard Fairclough House
Warrington WA4 1HG
Tel: 01925 653 999
Fax: 01925 415 961
The Castle Business Park
Stirling FK9 4TR
Tel: 01786 457 700
Fax: 01786 446 885
World Wide Web: http: // www. sepa. org. uk
NORTH REGION HQ
Dingwall Business Park
Dingwall IV15 9XB
Tel: 01349 862 021
Fax: 01349 863 987
WEST REGION HQ
5 Redwood Crescent
East Kilbride G74 5PP
Tel: 01355 574 200
Fax: 01355 574 688
EAST REGION HQ
Heriot-Watt Research Park
Edinburgh EH14 4AP
Tel: 0131 449 7296
Fax: 0131 449 7277
23 Castle Place,
Tel: 028 9025 4868
Fax: 028 9025 4777
Rio House, Waterside Drive, , Aztec West
Almondsbury, Bristol BS32 4UD.
Tel: 01454 624 400 Fax: 01454 624 409
World Wide Web: http: // www. environment-agency. gov. uk
West Sussex BN11 1LD
Tel: 01903 832 000
Fax: 01903 821 832
Exeter EX2 7LQ
Tel: 01392 444 000
Fax: 01392 444 238
Kings Meadow House
Kings Meadow Road
Reading RG1 8DQ
Tel: 0118 953 5000
Fax: 0118 950 0388
St Mellons Business Park
Cardiff CF3 0EY
Tel: 029 2077 0088
Fax: 029 2079 8555
A number of serious incidents involving dairies have occurred as a result of dairy products such as milk and yogurt which have passed their "sell-by" date being put into compactors. A compactor is not suitable for disposal of food wastes or liquids, and any cartons should be fully drained before compaction. Even when used for solid refuse, compactors often leak polluting liquids. They should, therefore, be isolated from the surface water drainage system, using a spill tray, raised kerbs or "roll-over" bunds, preferably covered, to avoid rainwater accumulation, and connected to the foul sewer if possible. Any leakage should be cleaned up straight away, using sand or absorbent material. Compactors are exempt from the need for a waste management licence, but must be registered with the Agency.
b. Treatment and pre-treatment plants
Adequate provision should be made for storage and handling of sludge produced from such plants. At times of adverse weather, discharge to land may be inappropriate and storage facilities should be sized to take this into account. The work of any contractors should be closely monitored, as you could be held responsible should they cause pollution. If sludge is to be spread beneficially on land, it may be exempt from waste management licencing. However, contractors should comply with relevant regulations (Reference 4) and codes of practice (Reference 5). The formulation and implementation of Farm Waste Management Plans at farms used for spreading will minimise the risk of pollution. Contact your local agricultural advisor for advice on Management Plans.
1. PPG11: Preventing pollution on industrial sites
2. PPG13: High pressure water and steam cleaners
3. PPG2: Above ground oil storage tanks
4. Sludge (Use in agriculture) Regulations 1989: The Stationery Office: Telephone 08706 005522
5. Code of good agricultural practice for the protection of water: MAFF Publications, telephone: 0645 556000
Code of good practice for the prevention of environmental pollution from agricultural activities: Scottish Executive Rural Affairs Department( SERAD): Telephone 0131 556 8400, Edinburgh
Water -Preventing pollution, series of 11 leaflets: Department of Agriculture for Northern Ireland
References 1-3 are available free of charge from your local Agency office. The Agencies produce a number of further guidelines and leaflets to help industry to avoid pollution, including a video -Pollution
Prevention Pays. For a full listing, contact your local Agency office. 4