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The storage of packaged dangerous substances in substantial quantities may create serious risks, not only to people working at the warehouse but also to the general public and to the environment. The precautions should be taken achieve a reasonable standard of control of the properties of the substances to be stored, eg flammable, corrosive, and toxic. Different substances create very different risks and it is important that the standards adopted at the warehouse are based on an understanding of the physical and chemical properties of the substances concerned and the potential reactions between substances.
Other important factors are the overall quantities of the substances to be stored and the maximum size of individual packages. The incidents that cause the greatest concern are generally those that involve fire. Such fires expose employees, the emergency services, and members of the public to the threat of heat, harmful smoke and fumes, flying missiles etc. Fires can also cause the substances to be spread over a wider area through smoke and water used to fight the fire, thereby being harmful to the environment.
Common causes of these incidents include,
- lack of awareness of the chemical properties of substances
- ignorance due to a lack of training
- inappropriate storage conditions with regard to the substance hazards and substance reactions with other substances stored nearby
- poor control over ignition sources, including those introduced by maintenance work
- vandalism and arson
- inadequate building design, equipment installation, maintenance
- exposure to heat from a nearby fire
At all warehouse, the manager should assess the following, to control risks.
- identification of substance(s) present or likely to be present
- evaluation of risks posed by these substances
- prevention and control of risk
- mitigation of risk
It is recommended that the company safety policy should include all this. The risk assessment should be periodically reviewed when the types of substance, total quantities or storage conditions change.
Identification and assessment
Information
The hazards of packaged dangerous substances should be identified by discussion and/or correspondence with the supplier before the substances are accepted for storage. Manufacturers and suppliers have a legal duty to provide adequate information about any risks to health or safety to which the inherent properties of a dangerous substance may give rise and about any conditions necessary to ensure that the substance will be safe and without risks to health when it is being used, handled, stored or transported.
Actions pre-arrival on-site of hazardous substances
Some substances will require special conditions for storage such as segregation, separation, not to be stored under sprinkler systems, store at a defined temperature range etc. These should be identified before the goods are accepted. The additional information obtained from the manufacturers and suppliers may identify specific examples of non-compatibility, and storage locations should take account of this. Substances requiring special conditions should only be accepted for storage when the required conditions can be made available, and maintained, at the warehouse.
Actions on arrival on-site of hazardous substances
On arrival, the contents of each consignment or individual package should be checked, identified and assessed against the shipment documents to verify acceptability. The goods should be checked to ensure they match the original agreed consignment as well as the lorry drivers’ delivery ticket. Dangerous substances should usually be identifiable by the transport labeling attached to the outer layer(s) of the packaging. It should be remembered that these labels and markings refer to the transport of dangerous goods and not to the storage considerations. Warning labels and information pertaining to the safe storage, handling and use of substances will be found on the MSDS and on the inner packages.
If the contents of any package are not immediately identifiable, it should not be sent to store. Such packages should be held in quarantine and only for the minimum time necessary to obtain information, or the supplier should be required to have them removed from the site promptly. Once the storage location for a consignment has been allocated, and before the materials are put into the store, a physical check should be made to confirm that adjacent materials are those shown on stock records. This is to ensure that the materials are compatible for storage and will not adversely react if exposed to one another. If all or part of a consignment is moved during its period of storage, the check procedures should be repeated to ensure that the new storage location will still be valid.
Risk prevention and control strategy
Package integrity
The primary protection against the dangers arising from storing dangerous substances is the integrity of the packaging. Individual containers may leak, break or be punctured, causing a small escape of material, and you should have arrangements in place to deal with this eventuality. Much greater risks arise where a large number of containers fail in a short time, and the principal means by which this may occur is fire.
Segregation
Often the first material ignited in a fire is not itself a dangerous substance. For this reason, stocks of combustible materials, such as easily ignitable packaging, should not be kept in storage areas with dangerous substances. Separate storage areas should be provided. Similarly, even small quantities of dangerous substances stored in a warehouse for general goods may seriously increase the consequences of any fire, and add to the dangers for the fire brigade. Dangerous substances should preferably be stored in dedicated compartments of the warehouse, which are effectively fire-separated from the rest of the building. The intensity of a fire, or its rate of growth, may be increased if incompatible materials are stored together. In addition, a fire may grow and involve dangerous substances which of themselves are not combustible. As a result of fire, toxic materials may be widely dispersed, either due to the nature of the individual substances, the mixture of unconfined substances, or as a result of incomplete combustion. To prevent this type of escalation, or adverse reactions, a system of segregation is necessary in a warehouse storing dangerous substances.
Ignition sources
All possible sources of ignition (eg smoking, maintenance work, electrical power supplies, arson, heating systems, warehouse vehicles and battery charging facilities etc) should be strictly controlled to reduce the risks to an acceptable level.
Handling
All packages containing dangerous substances should be handled carefully to avoid damage to the containers, or spillage of the contents. Damaged or leaking containers should not be placed in store, but should be repacked or disposed of safely in accordance with arrangements made with, or information provided by, the supplier. The requirements of Hazardous Waste Regulations should also be met when disposing of damaged packages. Repacking should be carried out in an area remote from the main storage areas and following risk assessment. Leaking containers should be placed in, or on, a suitable bund or tray to enable any leaking product to be captured while awaiting repacking or disposal.
Stock control
Storerooms and compounds should not be overstocked, and permanent instructions should specify a maximum storage capacity for each location. Gangways should be kept clear of obstructions, especially those designated as means of escape. At least 1 m of clear space should be left between all stock tops and the warehouse roof, roof beams or light fittings. Where sprinklers are fitted, spacing should be in accordance with the design code for the system. This information should be available from the system installers. Care should be taken with stores fitted with sprinkler systems as some products should not be stored in such areas.
Where a number of different types of dangerous substance are stored, a comprehensive record of stocks, providing details of the quantity, nature and exact location of all dangerous substances in a store, should be made and carefully updated each time a stock movement occurs. Keep a copy of the records available at a point on the site that is unlikely to be affected in an emergency, so that they can be used by both management and the emergency services when dealing with an incident.
Storage stability
Some types of substances may degrade or become unstable during prolonged storage or if stored at incorrect temperatures. These substances should be identified by information from the supplier, manufacturer or MSDS. Maximum recommended storage times should not be exceeded and this should be achieved by careful stock rotation. The advice of the supplier should be sought if material is found which has reached, or is about to reach, the recommended latest storage date.
Any stock held for a prolonged period should be inspected at intervals to detect any damaged or degrading packaging. Records of inspections should be maintained. Temperature ranges should be carefully managed to ensure that ambient temperatures in the defined storage area do not fall below or exceed the specified range. Have an escalation procedure in place to provide guidance if something wrong happens.
Spillages
Ensure that there is a safe system of work to deal with spillages. When dealing with spillages, all non-essential or untrained staff should be evacuated from the danger area. Provide sufficient equipment at strategic locations to enable trained personnel to manage foreseeable spillage incidents. Highlight the risk of incidents during risk assessment, along with any control measures required.
Liquid spillages
Where liquids are stored, provide methods for containing spillage. Barrier materials such as sand bags or proprietary absorbent pads/socks/granules are recommended, depending on the nature of the substance and the quantities involved. The chosen absorbent should not adversely react with the substance to be absorbed.
Solid spillages
Spillages of dangerous substances in a fine dusty form should not be cleared up by dry brushing. Vacuum cleaners should be used in preference, or damp sweeping, and for toxic materials.
Personal protection
Personal protective equipment will be necessary for dealing with accidental releases of dangerous substances. Protective footwear, gloves and eye protection are likely to be the minimum requirements. In some cases, additional items will be needed, eg respiratory protective equipment. When corrosive materials have been spilled, take care to ensure that people dealing with the spillage wear clothing with the necessary protection. Clothing contaminated with any dangerous substance should be removed immediately. Spare overalls should be available on site. Contaminated clothing should not be sent with other general laundry, nor taken home. It may be cleaned by arrangement with a specialist laundry, or disposed of as hazardous waste.
Warning signs
Post warning notices or signs at entrances to a warehouse storing dangerous substances. Where 25 tonnes or more of dangerous substances are stored, the Dangerous Substances Regulations make specific requirements for posting hazard warning signs and the design of signs used. The fire brigade should be consulted about requirements for the sitting of signs.
Management and training
Appoint a senior member of staff to be directly responsible for the identification, assessment, handling and safe storage of all dangerous substances on site. The appointed person should have suitable qualifications, training and experience and be familiar with the legislation relevant to the activities undertaken. Written operating procedures should be adopted covering matters such as selection of storage locations, dealing with spillages and security arrangements. Instructions for dealing with an emergency should include the steps necessary to enable staff to easily identify and deal with damaged and leaking packages and containers. Training should be given in the use of safety and spill control equipment provided and in the actions to be taken in the event of fire, spillage etc identified during risk assessment.
