5-2 Hazard Analysis

Principal unique hazards associated with solidification/stabilization (ex-situ/in-situ) include:

a. Physical Hazards

(1) Description: During soil excavation, workers may be seriously injured or killed by heavy equipment such as front-end loaders, tillers, scrapers, and other equipment.

Control: Heavy equipment should be equipped with a backup alarm that alerts workers. When approaching operating equipment, the approach should be made from the front and within view of the operator, preferentially making eye contact. CONTROL POINT: Construction, Operations

(2) Description: Installation of auger/caisson systems poses mechanical hazards due to the use of large rotating augers. During the in-situ stabilization process, heavy equipment and materials, such as augers and caissons are periodically raised overhead and placed into position. Workers may be exposed to swinging equipment or crushing hazards if the equipment were to fall.

Control: A work zone should be established and only those personnel required to perform the task should be allowed in the zone. Lifting equipment should be inspected regularly and operated safely. Equipment should be raised only as high as needed. The movement of raised equipment should be minimized. Operators should avoid contact with auger edges, cables, and pipe, and should wear appropriate personal protective equipment (PPE) including hard hats, steel-toe shoes, instep guards, and appropriate clothing. CONTROL POINT: Construction, Operations

(3) Description: Rotating augers or backhoes pose hazards to workers as loose clothing may become entangled with the revolving augers.

Control: All loose clothing should be secured. Workers should stay clear of rotating and moving equipment. CONTROL POINT: Construction, Operations

(4) Description: Fire and explosion hazards may exist when using augers or other drilling methods if the auger contacts and/or ruptures underground utilities such as electric or gas lines or underground tanks. Also, underground obstructions, such as sewers and foundations, may cause drilling equipment to abruptly stop, resulting in unsafe drilling conditions. Electrocution hazards may also exist if large stabilization augers come in contact with overhead electrical wiring during placement or operation.

Control: To control utility contact hazards, identify the location of all below- and above-ground utilities prior to drilling. Contact local utilities and public works personnel to determine the locations of utilities. When there is any doubt or uncertainty, carefully excavate with a backhoe, probe with a metal rod, or hand excavate to determine the exact location of utilities. Once utilities are located, careful excavation by backhoe may be allowed. When raising a drill mast, always have an observer to the side to observe and direct the activity. Do not move the drilling rig with the mast raised. CONTROL POINT: Design, Construction, Operations

(5) Description: Pug mills and similar equipment used to mix soils may be equipped with unguarded drive shafts, sprockets, chains, pulleys, or other revolving/rotating mechanisms. Exposure to the unguarded equipment may result in workers becoming entangled.

Control: All moving mechanisms must be guarded to prevent accidental contact. Workers should operate the equipment only when guards are in place, and wear appropriate PPE and clothing. No loose clothing should be worn, shirt tails should be tucked in, and long sleeves should be buttoned. Long hair should be tied up, and restrained under hard hats. CONTROL POINT: Design, Construction, Operations

(6) Description: Solidification/stabilization can sometimes cause off gassing of dangerous substances. As an example, when quantities of magnesium are present, solidification/stabilization with cement will cause off gassing of hydrogen from a water-magnesium reaction and present a fire/explosion hazard. This can be a problem with stabilization in drums and other containers.

Control: The work areas where stabilization is taking place should be well ventilated and monitored as necessary for explosive gasses. CONTROL POINT: Construction, Operations

(7) Description: Steam pressure washing of equipment may expose workers to thermal or burn hazards, eye hazards due to flying projectiles dislodged during pressure washing, slip hazards from wet surfaces, and noise hazards.

Control: Thermal burns may be prevented by using insulated gloves (e.g. silica fabric gloves). Eye injuries and hearing loss may be prevented by wearing safety goggles and hearing protection during pressure washing activities. Slip hazards may be controlled by workers wearing slip-resistant boots and draining water away from the decontamination operation into a tank or pit. Walking surfaces should be drained and free of standing liquids or mud. CONTROL POINT: Construction, Operations

(8) Description: Depending on soil types, exposure to respirable quartz may be a hazard. Consult geology staff to confirm the presence of a respirable quartz hazard (e.g. to determine if soil types are likely to be rich in respirable quartz). As an aid in determining respirable quartz potential, sample and analyze site soils for fines content by ASTM D422, followed by analysis of the fines by X-Ray Diffraction to determine fine material quartz content.

Control: Worker exposure to dust rich in respirable quartz may be minimized by periodically wetting the soil with water or amended water or by the use of respiratory protection, such as a air-purifying respirator equipped with a HEPA(N100, R100, P100) filter/cartridge. CONTROL POINT: Construction, Operations

(9) Description: During site activities, workers may be exposed to direct and indirect sunlight and the corresponding ultraviolet (UV) radiation. Even short-term exposure to sunlight can cause burns and dermal damage. Exposure to hot and humid conditions may also result in heat stress, which can manifest itself as heat exhaustion and heat stroke.

Control: Exposure to direct and indirect sunlight should be minimized where possible in the summer months. Workers can minimize direct sun exposure by wearing long-sleeve shirts and full-length pants, and by applying UV barrier sunscreen. If possible, the work and break areas should be shaded. Exposure to heat stress conditions can be minimized by taking frequent breaks, drinking adequate fluids, and performing work during the early morning and late afternoon hours. CONTROL POINT: Construction, Operations

(10) Description: Workers may be exposed to electrocution hazards when working around electrical utilities such as overhead power lines.

Control: The location of overhead power lines, either existing or proposed, should be noted in the pre-design phase. All lifting equipment, such as cranes, forklifts, and drilling rigs should remain at least 10 feet from the power line according to Occupational Safety and Health Administration (OSHA) regulation 29 CFR 1926.550 and EM 385-1-1, Section 11.E. CONTROL POINT: Design, Construction, Operations

(11) Description: The heavy equipment (small and large) used for site operations may roll over on steep slopes or unstable ground, crushing the operator.

Control: The angle of the slope should be designed to minimize the potential for roll-over. The construction contractor must maintain safe operating conditions for equipment during construction. Heavy equipment should be equipped with roll-over protective devices (ROPS) and should not be operated on steep slopes or unstable ground. CONTROL POINT: Design, Construction, Operations

(12) Description: During the implementation of field activities, equipment and workers may come in close proximity to traffic. Also, drilling rigs and other equipment may need to cross or use public roads. The general public may be exposed to traffic hazards and the potential for accidents during loading and transporting soil.

Control: Where equipment is to cross roads, warning signs should be used according to the criteria of the Department of Transportation Manual on Uniform Traffic Devices for Streets and Highways. A traffic management plan should be developed before remediation activities begin to help prevent accidents involving site trucks and automobiles. EM 385-1-1, Section 21.I.10 provides plan details. CONTROL POINT: Design, Construction, Operations

(13) Description: Manual lifting of heavy objects may expose workers to back, arm and shoulder injuries.

Control: Workers should not be required to lift heavy loads manually. Some loads may require two people. Proper lifting techniques include stretching, bending at the knees, and bringing the load close to the body prior to lifting (see EM 385-1-1, Section 14.A). Mechanical lifting equipment, such as forklifts, should be used to lift or to move loads whenever possible. CONTROL POINT: Design, Construction, Operations, Maintenance

(14) Description: The operation of both in-situ and ex-situ solidificatin/stabilization systems may present a noise hazard to workers.

Control: Workers should wear hearing protection in accordance with 29 CFR 1910.134 requirements as necessary, around operating equipment. CONTROL POINT: Construction, Operation

b. Chemical Hazards

(1) Description: During excavation and mixing operations (in-situ or ex-situ), workers may be exposed to inhalation/ingestion/dermal hazards from airborne contaminated dusts, volatile organic compounds (VOCs) and waste materials. These materials may include: Portland cement, quicklime, hydrated lime, kiln dust, fly ash, sodium silicate and gypsum. Also, the addition of cement may result in chemical release to the air due to chemical reactions with waste materials. Eye exposure to airborne dusts and chemicals may occur, resulting in irritating, scratching and scarring of eyes. High-pressure injection of stabilizing compounds can spray or splatter chemical agents which may also cause eye damage.

Control: The generation of airborne contaminants may be reduced by the periodic application of water to the active excavation and mixing areas. Injection equipment should have pressure-trip interlocks to prevent operation at excessive pressures. Other exposure controls include the selection of the proper types of PPE (e.g. an air-purifying respirator equipped with approved filter/cartridges [HEPA filters for particulates, OV cartridges for vapors, or combination filter/cartridges for dual protection] and eye protection). Worker exposure can also be minimized by frequent health and safety awareness meetings, use of experienced workers, and decontamination stations. CONTROL POINT: Design, Construction, Operations

(2) Description: During the excavation process, accidental rupturing of underground utilities, such as sewers and pipelines containing gases and liquids, may result in worker exposure to chemicals.

Control: Techniques to help prevent the rupture of underground utilities include locating the below-ground utilities and probing with a metal rod prior to excavating. CONTROL POINT: Construction, Operations

(3) Description: Enhanced off gassing of VOCs may occur as a result of the heat generated during the stabilization process. Also, ammonium compounds may release ammonia when mixed with cement. Workers may be exposed to VOCs via inhalation or dermal exposure routes.

Control: The generation of airborne VOCs may be reduced by the periodic application of water or emission-suppressing foams to the active excavation and mixing areas. The addition of foam to control vapors may also create a slip and fall hazard. Workers should not walk on areas to which foam has been applied. Other controls may include minimizing the amount of soil agitation during mixing operations, the erection of wind screens and portable surface covers, the use of the proper types of PPE (e.g. an air-purifying respirator equipped with approved filter/cartridges [HEPA filters for particulates, OV cartridges for vapors, or combination filter/cartridges for dual protection]), frequent health and safety awareness meetings, use of experienced workers, decontamination stations, and other standard procedures. CONTROL POINT: Design, Operations

c. Radiological Hazards

Description: Contaminants in excavated or in-situ soils, sludge, and associated water may pose a rare radiation hazard. Naturally occurring radioactive material (NORM) may be present in the soils, sludge and groundwater. Some radioactive materials are pyrophoric. Radioactive materials of uranium or thorium may spontaneously ignite and pose a fire hazard and an airborne radioactivity hazard. Radioactive materials buried in existing landfills being excavated may present an external hazard. All radioactive materials may present an internal hazard through inhalation or ingestion.

Control: The nature of the soil, sludge, and water contaminants may be known or tested to eliminate exposure during excavation, classification, and disposal. The presence of radiation or particulate radioactive materials, and their nature and extent, should be determined by a qualified health physicist. The appropriate engineering, PPE, and other controls should also be used to prevent exposure. Decontamination facilities should be available to help minimize exposure. Dust and other emissions should be suppressed using periodic applications of water or amended water. CONTROL POINT: Design, Operations

d. Biological Hazards

(1) Description: At those sites involving medical wastes or sewage sludge, microorganisms in the soil may pose exposure hazards during soil mixing and waste stabilization activities. Workers may be exposed to inhalation/ingestion/dermal contact with pathogens such as Coccidioides sp., Histoplasma sp., and Mycobacterium sp.

Control: Microorganisms present in the soil may be known or tested, and the appropriate PPE used to help control exposure. The generation of airborne contaminants, including microbes and particles (dust), may be reduced by the periodic application of water or emission-suppressing foams to the active excavation and mixing areas. The addition of foam to control vapors may also create a slip and fall hazard. Workers should not walk on areas to which foam has been applied. Other controls may include the use of the proper types of PPE (e.g. an air-purifying respirator equipped with approved filter/cartridges [HEPA filters for particulates, OV cartridges for vapors, or combination filter/cartridges for dual protection]), frequent health and safety awareness meetings, use of experienced workers, decontamination stations, and other standard procedures. CONTROL POINT: Design, Construction, Operations

(2) Description: Workers may be exposed to a wide array of biological hazards, including snakes, bees, wasps, ticks, hornets, and rodents, during any phase of remediation. The symptoms of exposure vary from mild irritation to anaphylactic shock and death. Deer ticks may cause Lyme disease.

Control: Periodic inspections of the site should be performed to identify stinging insect nests and for the presence of snakes. Professional exterminating companies should be consulted for removal. Tick and insect repellents may be used for exposure control. However, workers should check their skin and clothing for ticks periodically throughout the work day. CONTROL POINT: Construction, Operations, Maintenance