Science of Risk Management


By Dr Moses Amweelo

Risk management in water and sewerage operations

Risk management in community development planning is a salient feature of industrial progress though often ignored by some entrepreneurs who stand to benefit to the detriment of the worker.

The largest section of our population is rural based and in this sector the subject of risk management and environment are posed in completely different terms.

The degree of awareness and of organization of rural workers is still insufficient. The risks arising from working conditions and the environment are complex in nature and require sophisticated methods of approach in dealing with them.

Water treatment involves physical, chemical and biological changes that transform raw water into potable water. The chemicals used mostly for water treatment are aluminium sulphate, chlorine gas, lime and soda ash or sodium carbonate.

The handling storage and use of these chemicals requires careful attention. Chemicals are sources of explosions, violent reactions, burns, loss of eyesight and occupational illnesses.

Aluminium sulphate handling and storage:

– Store in a clean dry place.

– Do not use compressed air to clean, dry-feed machinery and auxiliary equipment.

– Chemical solution pumps must be shielded to protect personnel from splatter.

– Mechanical dust collecting equipment should be used to minimize dust.

– Respiratory protection and chemical goggles must be used when personnel are handling or exposed to the chemical. Loose dustproof, long-sleeved clothing should be worn and a cap. Trousers should be tied at the ankles. Exposed skin surfaces should be covered with a protective cream.

– Exposure to the dusts must not exceed eight hours.
Lime handling and storage:

– Store in dry place.

– Do not mix dry quick lime with dry alum or similar materials. An explosion hazard can be created.

– Wherever dust is a problem, a dust collection system should be provided.

– When exposed to dust, persons must wear goggles and respiratory protection. Skin exposure should be minimized by protective clothing.

– A shower should be taken after lime is handle
Soda ash (sodium carbonate) handling and storage:

– Store in a cool dry place.

– Ventilation and/or dust collection systems should be used to minimize dust.

– Pumps and equipment handling solutions should have spray and splash guards.

– Danger areas should be posted with warnings signs.

– Persons exposed to dust must wear chemical safety goggles and respiratory protection.

– Exposed skin surfaces should be covered by protective creams.
Chlorine handling and storage:

– Handle cylinders carefully. Do not permit them to collide with one another.

– Store cylinders in a secured place where they cannot be struck by other objects.

– Except when the cylinder container is in use, keep the protective cap in place.

– Store the cylinder in a cool place.

– Inspect the cylinders regularly for leaks.

– Use the oldest cylinder first.

Laboratory work

In laboratories including those involved in animal research, workers are exposed to various chemicals in addition to accidents which may result while carrying experiments and tests. Main occupational risks in this field include:

– Bodily injuries caused by explosions, broken apparatus and chemical burns.

– Poisoning by inhalation of toxic gases released during testing.

– Diseases transmitted by animals. The pathogenic organisms concerned include bacterial, viruses and protozoa.

Sewerage disposal

In sewage works, the main occupational hazards include high temperatures and humidity inside the sewage system. There are also toxic gases such as carbon monoxide, methane, hydrogen sulphide, benzene and other aromatic hydrocarbons, ammonia and carbon dioxide which can be produced from the interaction of industrial influents and poorly ventilated sewers. Other hazards of concern in this fields are such diseases as leptospirosis (Well’s disease), cardiovascular degeneration indicated by elevation of blood pressure, dermatitis caused by chemical irritants in the sewage system and conjunctivitis due to contact with fumes.

Water and Waste Water Analysis
One of the most used pieces of equipment in water and waste analysis is an atomic spectrophotometer. These use compressed gases, e.g. oxygen and acetylene. The laid down standards for handling these gases are:

– Cylinders must be legibly marked (at least 1 inch letters) identifying the gas content.

– Cylinders must be stored in assigned places away from elevators, stairs or gangways and in a well-protected place, ventilated and dry.

– Cylinders must be inspected to determine that they are in safe condition.

– Cylinders must have approved pressure relief devices installed and maintained.

– Cylinders must be kept in an upright position and chained, tied or otherwise securely held in this position while stored in use or transported by power vehicles.

– Except while in use, the valve protection cap must be in place.

– Valves must be closed when work is finished and also on empty cylinders.

– Cylinders, cylinder valves, coupling, valves, regulators, hoses and other apparatus must be kept free of oil and grease.

– Valves must be open by hand. Hammers and wrenches must not be used.

– Cylinders must be kept as far away from the welding and cutting operations as is necessary to ensure that the sparks or flames do not reach them.

– Cylinders must be moved by fitting and rolling.

– Do not drop or bump violently.

– Oxygen, acetylene and fuel gas cylinders must not be taken into confined spaces.

– Damaged or defective cylinders must not be used.

In conclusion, it should be noted that it is the policy of the government to reduce or minimize human suffering and economic waste due to the occupational risks and accidents or diseases associated with working conditions and environment. It is also government policy that all environmental considerations be incorporated in development planning implementation at all levels of decision making.


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