22-2 Hazard Analysis

Principal unique hazards associated with ion exchange (liquid/vapor)/resin adsorption (liquid/vapor) include:

a. Physical Hazards

(1) Description: Workers may be exposed to electrical hazards when working around resin beds. Permanent and temporary electrical equipment, which is not ground-fault protected and comes in contact with water or other liquids, may cause electrocution.

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, including adequate ground-fault protection, should be in conformance with the requirements of EM 385-1-1, Section 11.G; NFPA 70; and CEGS 16415: Electrical Work, Interior for the identified hazard area. CONTROL POINT: Design, Construction, Operations, Maintenance.

(2) Description: Improperly selected materials of construction, such as untreated steel, can corrode or dissolve to a point of failure and cause damage to the facilities or expose workers to crushing hazards associated with falling or collapsing equipment.

22-1 Ion Exchange/Resin Adsorption

Control: Liquid transfer equipment (pumps, piping, pipe fittings, valves and instruments) in contact with process liquids or chemicals should be fabricated from materials that are chemically-resistant to the liquid streams. Hydraulic Institute standards HI 9.1-9.5 discuss appropriate materials for pumping various fluids. Typical chemical resistance charts can be found through the National Association of Corrosion Engineers (NACE). CONTROL POINT: Design, Construction, Maintenance

(3) Description: Ion exchange systems consist of pressurized beds (e.g. tanks, pumps and piping). Pressurized systems can leak or fail, causing exposure to the contaminated influent stream and/or backwash or reconditioning chemicals.

Control: For systems requiring pressurized beds, design tanks and piping for the maximum operating pressure expected. Hydro test all systems in accordance with CEGS 11250 (Water Softeners, Cation-Exchange [Sodium Cycle]) before the system is put into operation. Where leaks may occur, containment drip pans or receivers may be included in the design. Design features should prevent the commingling of chemicals. Spill and/or leak detection instruments can be installed to monitor for leaks or spills and set off alarms when appropriate. CONTROL POINT: Design, Construction, Operations

(4) Description: Some systems have automatic backwash cycles during which the resin is regenerated by flushing with an acid or base. Failure of these automated backwash systems may expose workers to possible physical hazards associated with a disrupted process or to a chemical exposure.

Control: Backwash automatic controls should be designed into the system. Back-up control logic should be included to alarm and shut down systems if primary controls fail to shut down the system. CONTROL POINT: Design, Operations, Maintenance

(5) Description: Workers may be exposed to a fire or explosion hazard if, during regeneration of the resin, the heat of the reaction is sufficient to ignite VOCs which may have accumulated within the vessel.

Control: In vapor-phase systems, the vessel's atmosphere may be swept or purged with inert gas prior to, and/or during, the regeneration phase to help prevent an explosion or fire. CONTROL POINT: Design, Operations, Maintenance

(6) Description: Workers may be exposed to an explosion hazard during the mixing of incompatible chemicals. The resulting reaction may generate heat and pressure buildup causing an explosion.

Control: The system design should include process controls which shut down the system during over-pressurization. These controls may include emergency warning alarms and pressure-relief valves and vents that discharge away from the work area. CONTROL POINT: Design

(7) Description: Permanent or semi-permanent treatment buildings may present life safety hazards such as inadequate egress, fire suppression systems, and/or emergency lighting systems.

Control: Permanent and semi-permanent treatment system buildings should be constructed in accordance with ANSI 58-1: Minimum Design Loads for Buildings and Other Structures; the National Fire Code, the National Standard Plumbing Code; Life Safety Code, and the Uniform Building Code. Depending on where the project is located, the structures must also comply with either the Air Force Manuals on Air Force bases, the USACE Technical Manuals on Army installations, or Local Building Codes on Superfund, BRAC, or FUDS project sites. CONTROL POINT: Design, Operations

(8) Description: Emergency shower/eye wash equipment required per 19 CFR 1910.151 is not always provided with adequate floor drains, thereby creating potential electrical hazards or walking surface hazards during required testing/use.

Control: Showers/eye wash equipment should be equipped with accompanying functional drains to isolate and collect the shower/eye wash water from unprotected electrical equipment and walking surfaces that, when wet, create slipping hazards.

(9) Description: Ion exchange resins are generally fabricated from flammable materials that can be ignited under certain operating and storage conditions.

Control: The appropriate resin Material Safety Data Sheets and resin manufacturers= recommendations should be consulted and adhered to regarding proper resin use and storage. CONTROL POINT: Design, Construction, Operations

b. Chemical Hazards

(1) Description: Resins (solid or semi-solid organic materials) used in ion exchange treatment technologies may have specific storage requirements regarding heat and moisture content and may deteriorate, producing potentially hazardous conditions (such as acidic conditions). Acids (sulfuric and hydrochloric) and bases (such as sodium hydroxide) used during backwash or regeneration are incompatible with each other and should be stored separately or separated in the containment area. Inadequately contained reagents or spills of incompatible reagents in common storage areas may generate fumes or cause fires.

Control: Resins should be stored under the conditions required by the Material Safety Data Sheets. The quantity of resin stored should not exceed the amount of resin that can to be used within the acceptable storage period. Incompatible materials, such as acids and caustics, should be stored separately, or in individual secondary containment. Storage systems should be designed based on these incompatibilities using known process chemistry and MSDS information. It is important to design facilities that keep incompatible chemicals isolated from each other. Each chemical storage tank or drum should have adequate spill containment. Spill and/or leak detection instruments should be installed to monitor for leaks or spills and set off alarms when appropriate. Proper loading and chemical handling procedures are required. The backwash liquids should be handled with the same operational procedures as the process liquids. CONTROL POINT: Design, Operations, Maintenance

(2) Description: Workers may be exposed via the inhalation/ingestion/dermal exposure routes when adding chemical reagents and resins to the system. The chemical reagents may include sulfuric and hydrochloric acid. This activity may occur either at the initial loading of the materials or during the regeneration stage. The resulting exposure may cause burns, irritation, or more severe tissue damage.

Control: Handling of the chemical reagents and resins should be conducted under ventilated conditions and with the use of appropriate personal protective equipment (PPE) (e.g. an air-purifying respirator with acid gas cartridges and butyl rubber gloves). An eye wash/chemical spill shower should be located in proximity to the chemical handling areas. CONTROL POINT: Design, Operations, Maintenance

(3) Description: Eludation of the captured heavy metals from the resin bed will produce a filtrate solution that contains elevated concentrations of the heavy metals in an acidic or basic solution.

Control: The backwash fluid solution should be handled with the same procedures and protocols as those used for process fluids (e.g. proper containment precautions and observing all personal safety measures when handling the fluid material). CONTROL POINT: Operations, Maintenance.

c. Radiological Hazards

Description: Because the ion exchange treatment technology may remove radionuclides from aqueous waste solutions, the potential exists for worker exposure to radionuclides during treatment of radioactive wastes. In some geological settings, dissolved naturally occurring radioactive materials (NORM) or radioactive contaminants may be drawn up with the groundwater. Depending on the chemical form, the radioactive contaminant may be trapped by the ion exchange resin and concentrated to a point where a radiation hazard may develop.

Control: The contents of the waste stream may be determined using process knowledge or testing. If present, the nature and extent of the radiation and/or radioactive materials should be determined. If any radioactive material above background levels is found, a qualified health physicist should be consulted to determine the exposure potential and any necessary engineering controls or PPE. CONTROL POINT: Maintenance

d. Biological Hazards

Description: Piping systems may become blocked with the buildup of microbial mass within the system. Pipes which become plugged may cause tanks to overflow, or the pressure may increase and exceed the design pressure of the system, causing leaks.

Control: Vessels and piping should be cleaned on a specified schedule, and inspected for plugging and restrictions. The system should be designed to indicate excess pressures, indicating restriction of flow. Relief valves should be designed into the system and maintained. CONTROL POINT: Design, Maintenance