Issues

Hazards by Area or Operation and Their Control

Hazards by Area

Laboratory

Laboratory workers in sewage treatment plants commonly come into contact with toxic chemicals. They are required to comply with OSHA’s Laboratory Standard (29 CFR 1910.1450); the Hazard Communication Standard (29 CFR 1910.1200); Comprehensive Environmental Response, Compensation and Liability Act and SARA (Superfund Amendments and Reauthorization Act) rules and regulations. Laboratory workers must be trained in safe laboratory procedures. A written safety program should be established and the procedures should be followed carefully.

General Procedures

  • Only authorized and trained workers should be allowed in the laboratory.

  • Wear coats or aprons while in the lab, and remove them when leaving the area. Gloves should be worn by all laboratory workers. Remember, not all gloves protect against all solvents. Choose the correct glove. Goggles or face shields and chemical shower/eye wash stations should be supplied when working with corrosives or acids that could splash.

  • All laboratory chemicals should be labeled in accordance with the Hazard Communication Standard and Chemical Hazard Plan with the chemical name and formula, information regarding the purity, and safety precautions for storage and handling. Record the date that chemicals are opened and safely dispose of expired or questionable chemicals. Material Safety Data Sheets should be easily available to all lab workers.

  • Do not eat, drink, chew gum or smoke in the lab or other areas where work is performed on infectious materials or where chemicals are present. Separate lunch areas should be provided. Food and beverages should not be stored in lab refrigerators or anywhere in the lab.

  • Never pipette by mouth. Automatic equipment or suction bulbs should be provided.

  • All chipped, cracked or broken glassware and sharp metal objects should be placed in a special puncture-resistant container for disposal.

  • Carbon dioxide or ABC type fire extinguishers must be provided and properly mounted and maintained. The areas around these extinguishers must be kept clear at all times for immediate use.

  • Centrifuges should be properly shielded. If a specimen breaks in the centrifuge, it should be washed and thoroughly disinfected after/before re-use.

  • Garbage cans should be covered and should be large enough to hold all refuse without spilling over.

  • Keep flammable materials in approved safety containers. Keep no more than one day’s supply in the work area outside of an approved storage cabinet. Refrigerators used for the storage of flammables must be of the explosion-proof type.

  • Oxygen cylinders should be stored in a separate, well-ventilated section of the laboratory, away from electrical and heat sources.

  • All electrical equipment (including radios, fans, etc.) must be effectively grounded. The disconnects for all equipment must be properly marked, and the areas around the breaker boxes must be kept clear.

Laboratory Hoods and Ventilation

Exhaust ventilation hoods are required in laboratories where toxic chemicals — solvents, bases or acids — are handled. Hoods should be designed to capture a contaminant at its source. Exhaust fans should carry fumes away from the worker, not draw fumes past the workers’ breathing area. Ventilation hoods should be checked monthly for proper operation.

Aerosols

Infectious diseases are often spread in laboratories due to aerosols or airborne droplets of infectious materials. Aerosols are generated by opening containers, blowing out pipettes, test tube mixers, centrifugation, open pouring, automatic pipettes, high-speed blenders, spills and accidents. Creating aerosols can be avoided by:

  • draining pipettes instead of blowing out;

  • capturing falling drops upon disinfectant gauze during transfers;

  • careful maintenance of equipment such as high-speed blenders;

  • sealing centrifuge buckets; and

  • prohibiting mouth pipetting.

Garage facilities

Poorly ventilated garages allow carbon monoxide and other harmful exhaust to build up when truck and equipment motors idle in the facility. Short-term exposure to carbon monoxide can cause fatigue and irritability, while long-term exposure may cause circulatory problems and increase the likelihood of heart problems.

To protect workers from carbon monoxide exposure, management should maintain adequate ventilation of garage facilities. Hoses that exhaust directly outside or are connected to mechanical ventilation should be connected to the tailpipes of vehicles. Management should make sure that vent pipes for underground gas tanks are located so vapors do not enter doors or windows.

All jacks and hoist equipment should be checked at regular intervals. Management should also institute a regular procedure for securing, blocking or cribbing vehicles on jacks.

Maintenance/Machine shops

Skilled maintenance workers risk injury from a variety of chemical exposures in and out of the shop.

  • Paints, thinners and other volatile material should be stored in Underwriters Laboratory (UL) approved storage cabinets. Storage rooms must have explosion-proof lights and ventilation with a minimum of six air changes per hour. Paint thinners and solvents should be stored in fire-resistant safety containers; proper containers should have clear labels, flash screens and self-closing lids.

  • To protect workers from vapors and to prevent fires, all flammable liquids must be kept in closed containers when not in use as well as tanks and pans used for cleaning parts.

  • Oily shop rags and paint rags should also be stored in specially marked safety containers and disposed of regularly.

  • Compressed air equipment can be extremely dangerous; compressed air can cause harm if it enters cuts or skin openings. Management should properly guard all rotating pulleys and belts on compressor motors. All air tanks must meet A.S.M.E. (American Society of Mechanical Engineers) Code (Boiler and Pressure Vessel Code Section VIII Division I) and have adequate safety relief valves.

Pumping stations

Toxic and flammable gases can also collect in pumping stations. A properly operating ventilation system is essential, particularly in underground stations where heavier-than-air gases may collect. Pumping station equipment also throws dust, oil and loose metal — especially when starting up after a shut-down. Workers should be alert to this potential hazard.

Pumping station floors and stairways can become very greasy and gritty and, therefore, must be cleaned routinely to avoid dangerous falls and accidents. Lighting should also be cleaned frequently to avoid poor visibility.

Wet wells

Flammable liquids may also enter wet wells due to discharge from industries or highway accidents. Where possible, the material should be traced and the sewer ventilated. Explosive gas detection devices should be permanently installed.

Since wet well floors may flood rapidly when pumps or power fail, special battery operated alarms should sound in the event of high water and whenever pumping action is inadequate. Workers should vacate the areas immediately. Until emergency pumping is available, workers should not re-enter the area.

For wet wells with fixed bar screens or bar racks (for removal of string materials or bulky waste), management should install slip-proof platforms for workers who manually rake and clean the debris from the bars.

Trickling filter plants

Older plants with trickling filter systems often provide an excellent breeding ground for “trickling filter flies.” Not only do workers have to contend with annoying or biting flies but they also risk injury from exposure to pesticides used to control the flies. Management must institute a safe procedure for applying pesticides and notify workers of the names and associated health hazards of all pesticides. Workers should be provided with respirators when necessary.

Imhoff tanks

Workers working around the Imhoff tanks should be aware that the Imhoff’s special design makes it an extremely dangerous tank to fall into. Most workers who have fallen into these tanks have died or been seriously injured due to the cyclone-like action of the Imhoff. The danger of this tank is increased by the fact that Imhoffs are older and many plants have permitted walkways and guardrails around the tanks to deteriorate.

Around Other Tanks

Life-preservers are essential around all tanks. Lives have been saved because these devices were available. In addition, there should be two ladder exits from every tank attached to the rail. Workers should wear safety lines in case of flooding.

Incineration

Sludge workers who operate incinerators are also exposed to hazardous dusts, ashes and soot. Chronic exposure to this dust and smoke may cause lung diseases such as bronchitis, emphysema, asthma and cancer. Incineration work areas should be enclosed and adequately ventilated. Also, because of the buildup of coal and oil leaks and danger of fire, good housekeeping is essential.

Manhole covers

Extreme care must be taken when removing manhole covers to avoid back injuries and explosions caused by sparks reaching explosive sewer gases in the manhole. If the cover sticks, a long pry bar may be used to loosen it. Tapping the cover around the outer edge with a non-sparking sledgehammer may help. Safety lenses should always be used when using a sledgehammer.

Once the cover has been loosened, an approved manhole hook should be used to raise the cover. To prevent back strains, avoid using tools that require workers to bend over. Safety shoes, hardhats and gloves should be worn when working with covers and in sewers. A ladder should always be used to climb in and out of manholes if there is any doubt about the integrity of the manhole steps.

Crawling through the sewers

Sewers are confined spaces. Sewer maintenance workers must routinely inspect the conditions of sewers. Along with the precautions described in the confined space section of this pamphlet, sewer maintenance workers should avoid entering older sewers where vitrified clay has collapsed into an “egg shell” configuration; when necessary, temporary shoring should be installed to protect workers from crumbling, deteriorating sewers.

For extended operations, a stable, well-lighted and identifiable manhole cage over the manhole shaft is desirable. It provides protection and serves as a handhold for climbing into and out of the manhole.

Workers should never enter sewers without a standby crew and adequate communications devices and safety lines. They should be in complete compliance with OSHA’s Permit-Required Confined Spaces standard. All equipment required for safe sewer work — air blowers, atmosphere testing equipment, harnesses, hardhats and life lines, protective clothing, communication equipment and tools needed for lifting manholes — should be provided before leaving the work yard.

Pests

Workers in the sewer system are annoyed and sometimes threatened by a wide variety of pests. Sewer maintenance workers often encounter biting flies and other insects as well as large rats which spread disease. Wild dogs and other potentially dangerous animals also roam plant grounds. In fact, 3 percent of all disabling injuries in sewage treatment plants result from animal or insect bites. To protect workers, management should institute programs that provide protection from rodents, insects and wild dogs and their bites.

In addition, management should:

  • eliminate animal and insect habitats;

  • eliminate standing water, cut weeds, remove trash and brush piles;

  • provide rabies shots to workers bitten by animals, where necessary, and all biting animals should be captured and held for investigation; and

  • provide protective clothing and equipment when pesticides are applied.

Asbestos

Asbestos is one of the most dangerous materials that can be found in any workplace. Older sewage treatment plants are full of deadly flaking asbestos. It can be found in fireproofing, pipe and boiler insulation, flooring materials, gaskets and many other building materials.

The health risk comes from the asbestos fibers that have come loose and are too small to see. These microscopic dagger-like fibers get lodged deep in the lungs and other internal organs. Exposure is known to cause serious diseases such as asbestosis (an irreversible scarring of the lung tissue) and cancer of the lungs, stomach, large intestine, rectum, and linings of the lungs and other body organs (mesothelioma).

Asbestos can cause cancer 20 or even 40 years after exposure. If workers carry asbestos dust home with them, their families can also become contaminated. If you are exposed to asbestos and you smoke, your chances of developing lung cancer are many times higher.

The first step to protecting workers from asbestos is to find out where it is. The facility should be surveyed by a certified asbestos inspector to identify which materials contain asbestos. Almost any material in a plant built before 1980 that is not metal, wood or glass could contain asbestos, and should be treated as such. The only way to know for sure if a material contains asbestos is to have a sample tested by a qualified laboratory.

Damaged and exposed asbestos-containing materials (ACM) should be removed, enclosed (encapsulated), or otherwise repaired. These tasks are forms of asbestos abatement, and can only be performed by properly trained, equipped and certified asbestos abatement workers.

Every facility that has asbestos, or presumed asbestos-containing materials (PACM), must have an operations and maintenance plan (O&M). The purpose of an O&M is to keep asbestos in good condition and to prevent damage to materials that contain asbestos. Special procedures must be used for cleaning, repair and maintenance on and around these materials. Workers must be provided with protective clothing and respirators, and special vacuums equipped with HEPA (high-efficiency particulate air) filters. HEPA-respirator cartridges have a purple or magenta-colored band.

The OSHA standards to protect workers from asbestos exposure are 29 CFR 1910.1001 and 29 CFR 1926.1101. The Environmental Protection Agency (EPA) also has laws against release of asbestos into the air and improper disposal.

Hazards by Operation

Welding

Welding can be an extremely hazardous activity. Only workers who are prop-erly trained, qualified and designated as welders should be permitted to operate welding equipment.

Welding “smoke” is a mixture of very fine particles (fumes) and gases. Many of these substances are extremely toxic. Welding fumes and gases are produced from the base materials that are being welded, filler materials, coatings, shielding gases, and chemical reactions between heat and energy from the arc and the surrounding air.

Health Effects of Welding

Exposure to welding smoke can have short-term and long-term health effects:

Metal Fume Fever

Exposure to metal fumes (such as zinc, magnesium, copper and copper oxide) can cause metal fume fever. Symptoms may occur 4 to 12 hours after exposure, and include chills, thirst, fever, muscle ache, chest soreness and nausea.

Smoke and Fumes

Welding smoke can also irritate the eyes, nose and respiratory tract. Some components of welding fumes, such as cadmium, can be fatal in a short time. Gases given off by the welding process can also be extremely dangerous. For example, ultraviolet radiation given off by welding reacts with oxygen and nitrogen in the air to form ozone and nitrogen dioxide. These gases are deadly at high doses, and can cause irritation of the nose and throat and serious lung disease.

Phosgene Gas

Ultraviolet rays given off by welding can also react with chlorinated hydrocarbon solvents, such as trichloroethylene, 1,1,1-trichloroethane, methylene chloride, and perchloroethylene, to form phosgene gas. Even a small amount of phosgene may be deadly. Early symptoms of exposure — dizziness, chills and cough — usually take 5 or 6 hours to appear. Arc welding should never be performed within 200 feet of degreasing equipment or solvents.

Ultraviolet Light

The intense light associated with arc welding can cause eye injuries. In addition, even a brief exposure (less than one minute) to invisible ultraviolet light (UV) from the arc can cause “arc eye” or “welder’s flash.” The symptoms of arc eye usually occur many hours after exposure to UV light, and include a feeling of sand or grit in the eye, blurred vision, intense pain, tearing, burning and headache.

Lung Disease

Studies of welders, flame cutters and burners have shown that welders have an increased risk of chronic lung disease, lung cancer and other respiratory cancers. Welders may experience a variety of respiratory problems, including pulmonary edema (fluid in the lungs), bronchitis, emphysema, coughing, wheezing, shortness of breath and siderosis (a dust-related disease caused by iron oxide dust).

Controlling Welding Hazards

Since welding poses many dangers to welders and their co-workers, the following procedures should be strictly followed.

  • Where welding is done in an enclosed space, local ventilation (hoods, exhausts, etc.) should be provided. Where ventilation is not adequate to keep levels of toxic gases to safe levels, workers should be provided with a respirator.

  • Proper protective equipment should be provided. This includes welder’s helmets, a flame-proof gauntlet, gloves, flame-proof aprons and goggles.

  • In electric arc welding, the electrical cables should be checked frequently to be sure they are not frayed, cracked or broken. The welding machine should be grounded — but not to a pipeline which may contain flammable gases.

  • All cylinders of compressed gas must be properly stored in dry, well-ventilated areas at least 20 feet from combustible materials. Acetylene cylinders should never be placed horizontally because of the possibility of leakage.

  • Welding is strictly prohibited in confined spaces unless the employer has implemented a permit-required confined space entry program and all procedures for “Hot Work” have been properly established. Because the nature of the hot work may alter the atmosphere in the confined space, all welding and cutting operations in confined spaces make them permit-required spaces. Tanks, wet wells, digesters, silos, hoppers and all other confined spaces must be monitored both before and during entry especially when hot work is being performed.

  • When welding is performed in confined spaces (such as tanks, digesters, wet wells, etc.), cylinders and valves must be kept outside the confined space so the attendant can shut them off in an emergency. A trained attendant must be stationed outside and equipped with appropriate gear (including a fire extinguisher and any other emergency equipment) needed to assist or summon rescue services for the entrant.

  • Compressed gas cylinders, all pressure relief valves and all lines should be checked before and during the welding operation.

  • Gasoline-powered electric welders are a hazard in enclosed areas because they create carbon monoxide. Adequate exhaust ventilation must be provided while the engine is in operation.

  • Never weld on containers that have held a flammable or combustible material unless the container is thoroughly cleaned or filled with an inert (non-reactive) gas. Otherwise, explosions, fires or release of toxic vapors may result. Containers with unknown contents should be assumed to be flammable or combustible.

  • The welder should be enclosed in an individual booth or by non-combustible screens that are painted with a finish of low-reflectivity.

  • Appropriate protective clothing should be worn by all welders and nearby workers during welding operations.

  • Cutters and welders must be trained in the safe operation of equipment.

Trenching/Excavating

Excavation of sewer lines can pose a major hazard to workers. Improper excavation and shoring of walls can lead to serious injuries if walls collapse or if surface water is allowed to penetrate the area.

To protect workers from trenching hazards, management should have a strict procedure that provides:

  • proper shoring, installed from the top down and removed from the bottom up, on trenches 5 feet deep or more;

  • placement of excavated soil at least 2 feet from the trench edge;

  • daily inspection of the excavation site for evidence of possible cave-ins or slides and after every rainstorm or freeze;

  • ladders every 25 feet in trenches over 4 feet deep, and the side rails of the ladder should extend at least 3 feet above the landing; and

  • warning vests for workers who emerge from excavation into traffic areas.

  • a standby person on the bank to remove dirt, and to watch and warn of the danger of a cave in.

Process Safety

OSHA has a regulation covering process safety management (PSM). PSM applies to wastewater treatment facilities that deal with more than 130 toxic and reactive chemicals. It also includes flammable liquids and gases in quantities of 10,000 pounds or more (except products used only for heating or fuel). This standard primarily covers AFSCME members who work in water and sewage treatment facilities that store chlorine in excess of 1,500 pounds or chlorine compounds in excess of 1,000 pounds.

According to OSHA, the term “process” in PSM means an activity involving a highly hazardous chemical including using, storing, manufacturing, handling or moving such chemicals at the site, or any combination of these activities. Any group of vessels that are connected or a separate vessel that is located in a way that could involve a highly hazardous chemical in a potential release, are considered a single process.

Process Safety Information

Employers must compile process safety information that includes:

1. Information about the hazards of chemicals used or produced by the process:

  • toxicity

  • permissible exposure limits

  • physical data

  • reactivity data

  • corrosion data and

  • thermal and chemical stability data, and hazardous effects of inadvertent mixing of different material.

2. Information on the technology of the process:

  • a block flow diagram or simplified process flow diagram;

  • process chemistry;

  • maximum intended inventory;

  • safe upper and lower limits for such items as temperature, pressures, flows or compositions; and

  • an evaluation of the consequences of deviations, including those affecting the safety and health of workers.

3. Information on the equipment in the process:

  • materials of construction;

  • piping and instrument diagrams (P&IDs);

  • electrical classification;

  • relief system design and design basis;

  • ventilation system design;

  • design codes and standards employed;

  • material and energy balances for processes built after May 6, 1992; and

  • safety systems (e.g., interlocks, detection or suppression systems).

Process Hazard Analysis

Employers must conduct a hazard analysis for each covered process. The analyses must be updated and validated at least every 5 years, and records of the most recent analyses must be maintained.

Process Hazards Analysis Methods

The employer must choose an appropriate method from:

  • WHAT-IF: A review of relatively uncomplicated processes from the raw materials to the product that is produced.
  • CHECK-LIST: A checklist for more complex processes used by the committee members having the greatest experience or skill in a particular part of the process.
  • WHAT-IF/CHECKLIST: The what-if/checklist combines the creative thinking of a team of specialists and a prepared checklist. The result is a comprehensive hazard analysis that is extremely useful in training operating personnel on the hazards of the particular operation.
  • HAZARD AND OPERABILITY STUDY (HAZOP): HAZOP is a method that examines each element of a system to identify areas where the system may not operate as designed and the hazards that could result.
  • FAILURE MODE AND EFFECT ANALYSIS (FMEA): The FMEA is a study of component failures. This review starts with a diagram of the operation, and includes all components that could fail and possibly affect the safety of the operation.
  • FAULT TREE ANALYSIS: A fault tree analysis can be a description or estimate of the danger that would result if a toxic gas was released or there was an explosion or other event.

The analysis must address:

  • hazards of the process;

  • previous hazardous incidents;

  • engineering and administrative controls;

  • consequences if engineering and/or administrative controls fail;

  • facility siting; and

  • human factors and evaluation of effects of failure of controls on workers.

The team performing the analysis must have expertise in engineering and process operations. The team must include one worker with experience and knowledge of the process and someone who knows about the hazard analysis method used by the team.

Operating Procedures

The operating procedures of the facilities must be in writing and provide clear instructions for safe operation. The procedures must be readily accessible to workers and be updated when necessary. The procedures must cover special circumstances such as lockout/tagout and confined space entry. The procedures must address at least the following elements:

  • Steps for each operating phase:

    • initial startup

    • normal operations

    • temporary operations

    • emergency shutdown (This includes the conditions under which emer-gency shutdown is required, and the assignment of shutdown responsibility to qualified operators to ensure a safe and timely shutdown.)

    • emergency operations,

    • normal shutdown, and

    • startup following a turnaround, or after an emergency shutdown.

  • Operating limits:

    • consequences of deviation, and

    • steps required to correct or avoid deviation.

  • Safety and health considerations:

    • the properties and hazards of chemicals used in the process;

    • precautions necessary to prevent exposure, including engineering controls, administrative controls, and personal protective equipment;

    • control measures to be taken if physical contact or airborne exposure occurs;

    • quality control for raw materials and control of hazardous chemical inventory levels;

    • any special or unique hazards; and

    • safety system (e.g., interlocks, detection or suppression system) and their functions.

Training

Employers must train workers for specific safety and health hazards emergency operations and safe working practices. The initial training must occur before assignment or employers may certify that workers involved in the process as of May 1992 have the required knowledge, skills and abilities to safely perform duties and responsibilities specified in the operating procedures.

Refresher training must be offered at least every three years or more as necessary to workers involved in operating a process to ensure that they understand and follow the current operating procedures of the process. The training must be documented in writing.

Worker Involvement

Employers must develop a written plan of action regarding worker participation. They must consult with workers and their representatives on the conduct and development of process hazard analyses and on the development of other elements of process safety management required under the rule. Workers and the union have the right to access process hazard analyses and all other required information under the rule.

Employers must establish a system to:

  • address hazard analysis findings and recommendations;

  • document planned actions;

  • complete actions as soon as possible in accordance with a written schedule; and

  • notify affected operating, maintenance and other workers of planned actions.
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