16-2 Hazard Analysis
Principal unique hazards associated with precipitation include:
a. Physical Hazards
(1) Description: Solids from the precipitation process may plug
waste lines if the rate of precipitation exceeds the rate of solids removal.
16-1 Typical Process Flow for Precipitation
Plugged waste lines may cause tanks to overflow, causing slippery
conditions. Also, due to the wet environment and the use of electrical equipment, workers
may be exposed to electrocution. Overpressure in lines may also rupture piping or pumps.
Control: Equipment to help prevent lines from plugging, such as
auger-equipped waste lines or flow controls, may be used to help prevent plugged lines and
overflowing tanks. Hazard warning alarms may be installed to alert operators of system
over-pressurization. Adequate spacing should be left between equipment so that it can be
safely maintained. 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, both temporary and permanent, 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 70 requirements. Only trained and
experienced workers should be permitted in the areas. CONTROL POINT: Design, Operations,
Maintenance
(2) Description: Emergency shower/eye wash equipment required per 29
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. CONTROL POINT: Design
b. Chemical Hazards
(1) Description: Precipitation treatment may expose workers to
corrosive chemical reagents (e.g. HCL, lime, sodium hydroxide, carbonate salts, sulfide
salts, etc.) used in the process. The reagents may be in powder or liquid form, and may
pose an exposure hazard through either inhalation, dermal and/or ingestion routes. These
reagents may corrode piping system components. Some chemicals used in the precipitation
process are hygroscopic (water absorbing), and may develop unwanted reactions in the
presence of moisture.
Control: Controls to help minimize worker exposures may include the
delivery of chemical reagents (e.g. lime, sodium hydroxide solutions, etc.) through a
closed system, and/or the use of personal protective equipment (e.g. an air-purifying
respirator using cartridges appropriate to the reagents). Material Safety Data Sheets
(MSDS) should be consulted prior to handling reagents to determine the specific chemical
hazards associated with the chemicals. Hygroscopic chemicals should be stored separately
from other chemicals in air-tight containers. Design considerations should also
include the appropriate materials for piping and system components. CONTROL POINT:
Design, Operations, Maintenance
(2) Description: If the addition of chemical reagents in
oxidation/reduction reactions is not properly controlled, then the reaction may proceed
uncontrollably, causing a buildup of heat and pressure that causes a release from the
system. The release may involve worker exposure to chemical reagents or waste material.
Exposure may cause irritation or chemical burns to eyes, skin, and respiratory tracts.
Control: Flow controls may be needed to help prevent addition of
excessive amounts of chemical reagents (e.g, hydrochloric acid, sodium hydroxide, lime,
etc). The oxidation/reduction reagents should be stored in separate areas under cool, dry
conditions. Pressure-relief systems and over- pressurization alarms must be part of the
process design. An automatic shutoff should be installed to prevent the overflowing of
storage tanks. Chemical piping should be located low to the ground, if possible, in case
of rupture. If pipes are subject to moisture buildup, provide insulation on pipes to
prevent slipping hazards. CONTROL POINT: Design
(3) Description: Sludge from the treatment process may have a high
pH, which may cause skin burns for workers handling the material.
Control: Controls for this hazard may include neutralization of the
sludge prior to handling, or the use of personal protective equipment such as rain gear,
rubber gloves (e.g. butyl rubber for hydrochloric acid or sodium hydroxide), and splash
shields. CONTROL POINT: Design, Operations, Maintenance
(4) Description: The process may form metal sulfides, which may
generate toxic gases (including hydrogen sulfide), or the sulfide sludge may spontaneously
combust.
Control: Controls to help prevent worker exposure to hydrogen
sulfide include local ventilation to remove the gas from the work area, process tanks and
vessels, pH control to keep the sulfides alkaline, and water control systems to keep
sulfide filter cakes moist. Due to the potentially fatal consequences of overexposure to
hydrogen sulfide gas, a hydrogen sulfide monitor should be installed in these areas where
the generation of H2S is most probable. Monitors should be set to alarm at 10
ppm. Emergency escape respirators should be available for all operators in the event of a
catastrophic system rupture or uncontrolled reaction that would liberate excessive amounts
of H2S. CONTROL POINT: Design, Operations, Maintenance
(5) Description: Workers may be exposed to acids or bases used for
pH adjustment.
Control: The secondary containment storage areas for acids and bases
should be constructed of materials compatible with storage of these materials and clearly
marked. Acids and bases should be stored in separate areas. Emergency showers and eye wash
stations that comply with 29 CFR 1910.151(c) and the design requirements specified in ANSI
Z358,1 (1990) should be located near the reagent storage areas. Handling of pH agents
should be automated to the extent practical. An emergency plan should be prepared and
facility personnel should be trained to safely handle acids and bases. Manual handling of
acids and bases should be done by personnel familiar with their properties and equipped
with personal protective equipment (PPE), such as leather or rubber acid-resistant boots,
chemical-resistant coveralls, goggles and face shields, air-purifying respirators (as
indicated by the reagent), and rubber or other acid and base resistant gloves (e.g.
nitrile) or gauntlets. CONTROL POINT: Design, Operations, Maintenance
(6) 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 sites. CONTROL POINT: Design, Operations
c. Radiological Hazards
Description: Many radioactive materials and naturally occurring
radioactive materials (NORM) are metals, and if present in the water may be precipitated
out and concentrated. This hazard may be considered out of the ordinary for this
technology. Some radioactive materials may present an external exposure hazard. All
radioactive materials may present an internal exposure hazard through inhalation or
ingestion.
Control: Should elevated levels of radioactive contaminants be
present in the groundwater, a qualified health physicist should be consulted to determine
the exposure potential and any necessary engineered controls or PPE. CONTROL POINT:
Maintenance
d. Biological Hazards
Description: NONAPPLICABLE
Control: NONAPPLICABLE
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