11-2 Hazard Analysis

Principal unique hazards associated with air sparging/oxygen enhancement with air sparging include:

a. Physical Hazards

(1) Description: During the installation of groundwater wells, soil borings using hollow-stemmed augers may cause a fire or explosion during drilling into soils saturated with flammable or combustible materials. Sparks generated when a metal auger bit strikes against rocks, metal, or other underground objects may ignite a flammable atmosphere inside the bore hole. Fire or explosion may also result from drilling into soil contaminated with readily flammable/combustible wastes such as carbon disulfide, gasoline, or explosives such as metal fulminates. This hazard would typically be considered rare.

Control: The potential for a fire or explosion may be controlled by using mud or water rotary drilling methods, which add moisture to the cutting area, or by filling bore holes to prevent vapor accumulation. Always have adequate fire fighting equipment at hand to extinguish any fires generated. CONTROL POINT: Construction, Maintenance

(2) Description: Fire, explosion, or electrocution hazards may exist when using hollow-stemmed auger drilling methods if the rotating auger contacts and/or ruptures underground utilities such as electrical and gas lines, or contacts overhead electric lines.

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, conduct a utility survey, probe with a metal rod, prior to excavation, or hand excavate to determine the exact location of utilities prior to drilling. 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 guide. Do not move the drilling rig with the mast raised. CONTROL POINT: Design, Construction, Maintenance

(3) Description: Due to the presence of high levels of oxygen in an enhanced air sparge system, there may be an increased risk of starting a fire.

Control: Oxygen delivery systems should be regularly inspected for leaks and all sources of ignition. CONTROL POINT: Operations, Maintenance

(4) Description: Fires and explosions may occur due to emissions of flammable VOCs at the surface or in the SVE collection system. Sparks, heat sources, and static electricity may ignite explosive gases, causing rupture of the collection system.

Control: Verify that the hazardous area classifications, as defined in NFPA 70-500-1 through 500-10, are indicated on the drawings. All controls, wiring, and equipment used for the collection of flammable gases should be in conformance with the requirements of EM 385-1-1, Section 11.G and NFPA 70 for the identified hazard areas. Equipment should be grounded and/or provided with ground fault interrupter circuit (GFIC) protection if required by EM 385-1-1, Section 11 or NFPA requirements. Only trained, experienced workers should be permitted to work on the systems. The systems should be regularly inspected for leaks and all sources of ignition should be controlled. The areas should also be adequately ventilated to help prevent the accumulation of flammable gases. CONTROL POINT: Design, Construction, Operations, Maintenance

(5) Description: The rotating drilling auger poses a hazard to workers as loose clothing may become entangled with the revolving auger.

Control: Controls to help prevent workers from becoming entangled with the revolving augers include securing all loose clothing, using low-profile auger pins, and using long-handled shovels to remove soil cuttings from the borehole. CONTROL POINT: Construction, Maintenance

(6) Description: Blowers may be equipped with unguarded pulleys which may cause the entanglement of loose clothing.

Control: Unguarded pulleys and other moving or rotating mechanical devices on blowers should be guarded, and workers informed to only operate equipment with guarding in place. CONTROL POINT: Design, Operations, Maintenance

(7) Description: Piping systems which become plugged may induce failure of the vacuum pump, causing an electrical fire, or pipes or joints to burst from excessive pressure.

Control: Piping systems should be periodically inspected and cleaned to help prevent buildup of material which may cause blockage. CONTROL POINT: Design, Operations, Maintenance

(8) Description: Workers may be exposed to elevated temperatures due to excess heating of blowers and other process equipment. The exposure may induce heat stress.

Control: Blowers, motors, and other equipment should be correctly sized to prevent overheating. Vigorously train the workers in the signs and symptoms of heat stress, in combination with use of the "Buddy System" and easy access to water. CONTROL POINT: Design, Operation, Maintenance

(9) 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, Maintenance

(10) 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. CONTROL POINT: Design, Construction, Operations, Maintenance

b. Chemical Hazards

(1) Description: The use of oxygen or ozone enhancement may create an increased flammability potential or toxic (ozone) exposure.

Control: Adequately ventilate the affected area, and regularly inspect piping systems for leaks. CONTROL POINT: Design, Operations, Maintenance

(2) Description: During well installation, workers may be exposed to contaminants, such as VOCs, dusts, and metals, in soil and development water through the inhalation/ingestion/dermal contact routes.

Control: During well installation, workers may need to apply water or an amended water solutions to the area to help control the generation of airborne dusts, particulates, and VOCs. Workers may also use respiratory protection including the use of approved filter/cartridges (e.g. HEPA(N100, R100, P100) filters for particulates, OV cartridges for vapors, or combination filter/cartridges for dual protection). Personal exposure may be controlled by the use of personal protective equipment. An analysis of the work tasks and potential for chemical exposure should be performed to determine the correct personal protective equipment (PPE) and/or respirator cartridge(s), if needed. The analysis should include a chemical profile on the waste materials to help ensure the equipment specified will be appropriate for the respective chemical hazard. CONTROL POINT: Construction, Maintenance

(3) Description: During operation of the system equipment, workers may be exposed to chemical materials, such as hydrogen sulfide, VOCs, carbon dioxide, and intermediate byproducts by the inhalation/ingestion/dermal contact exposure routes.

Control: During operation, proper ventilation and PPE should be used (e.g. an air-purifying respirator with organic vapor cartridges; air-purifying respirators for H₂S exposure are for escape only). Closed systems, such as SVE, should be routinely checked for leaks with PIDs, air samples, O₂ meters, leak detection fluids, explosive gas meters, or specific gas tests such as Draeger-type tubes. Repairs of leaks should be done immediately. Vent stack heights should be adequate to disperse off gas. Designers should anticipate byproducts and products, and be certain that the technology selected for treatment (e.g. activated carbon, condensation, catalytic oxidation) of off-gas residuals is effective and safe. CONTROL POINT: Design, Operations, Maintenance

(4) Description: Ozone exposure may occur via the inhalation/dermal contact exposure routes from leaks in equipment used to generate ozone. Ozone is an irritant to skin, eyes and mucous membrane systems.

Control: Closed delivery systems for the addition of ozone should be used to help minimize worker exposure. The equipment used to generate ozone should be tested for leaks prior to use. Regular maintenance and leak tests should be performed according to the manufacturer's instructions. CONTROL POINT: Design, Operations, Maintenance

(5) Description: During handling of hydrogen peroxide, workers may be exposed to liquid hydrogen peroxide via the inhalation/ingestion/dermal contact exposure routes. Hydrogen peroxide is an irritant to the skin, eyes, and mucous membranes.

Control: Closed delivery systems for the addition of hydrogen peroxide should be used to help minimize worker exposure. The system should be tested for leaks prior to use. Regular maintenance and leak tests should be performed according to the manufacturer's instructions. CONTROL POINT: Design, Operations, Maintenance

(6) Description: Injection (sparging) wells may cause migration of VOCs into subsurface structures, such as basements and sewers. The VOCs may be toxic and/or flammable, resulting in chemical exposure or the potential for a fire or explosion.

Control: The system designer should determine the pressure range of the system and install hazard warning alarms to prevent over-pressurization. Periodic air testing should be performed in basements and other areas where VOCs may migrate to ensure safe levels. CONTROL POINT: Design, Operations, Maintenance

(7) Description: During entry into confined space, such as a manhole to collect condensate samples, workers may be exposed to airborne chemical hazards if the atmosphere in the confined space contains a toxic chemical or is oxygen deficient.

Control: A confined-space entry program, which includes worker training and air testing procedures, should be implemented prior to entering confined space. All atmospheres of confined space should be tested prior to and during entry. If a hazardous atmosphere is determined to exist, confined space should be ventilated and the hazards abated. CONTROL POINT: Operations

(8) Description: Biological degradation of certain chlorinated organic compounds may produce toxic intermediate products including vinyl chloride. Vinyl chloride exists as a gas and may accumulate to higher levels in boreholes or in the system. Workers may be exposed to intermediate products during operation or maintenance of the system.

Control: Controls to minimize exposure include local ventilation of the effected area. If ventilation or other engineering controls are not sufficient to maintain exposures to less than the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL), then select the proper respirator according to 29 CFR 1910.1019 or 29 CFR 1910.134 for other intermediate products. Check with the respirator manufacturer to ensure use in atmospheres containing vinyl chloride. CONTROL POINT: Design, Operations, Maintenance

c. Radiological Hazards

Description: In some geological settings, workers may be exposed to naturally occurring radon gas. The gas is drawn from the soil in the SVE stream. Radon gas and radon progeny do not present a significant external hazard. While breakdown products of radon (progeny) may present an inhalation/ingestion hazard, quantities of radon progeny normally present would not pose a significant exposure hazard.

Control: Proper operation of emission control technologies will limit exposure to acceptable levels. Should excessive levels be suspected from previous site knowledge, or should excessive levels or radon be encountered, a qualified health physicist should be consulted for proper guidance. CONTROL POINT: Design, Operations, Maintenance

d. Biological Hazards

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

Control: The generation of airborne microbe-contaminated dust during installation activities may be reduced by the periodic application of water, surfactant amended water, or emission-suppressing foams to the active excavation/drilling 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 erection of wind screens and portable surface covers, the use of the proper types of PPE (e.g. an air-purifying respirator with HEPA(N100, R100, P100) filter/cartridge and rubber gloves), use of experienced workers, repeated health and safety meetings, decontamination stations, and other standard procedures. CONTROL POINT: Construction, Maintenance

(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. Exposure to 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. Workers should check their skin and clothing for ticks periodically throughout the work day. CONTROL POINT: Construction, Operations, Maintenance