Table 3. Decontamination solutions for drilling equipment (from Moberly 1985).
Chemical
Solution
Uses/remarks
Sodium carbonate
4 lb/10 gal water
Neutralize organic acids, heavy metals, and
metal processing wastes
Sodium bicarbonate
4 lb/10 gal water
Neutralize either base or acid (baking soda)
contaminants
Trisodium phosphate
2 lb/10 gal water
Similar to sodium carbonate.
(TSP, Oakite)
4 lb/10 gal water
Good for solvents and organic compounds
(such as toluene, chloroform, TCE, PCBs)
Calcium hypochlorite
8 lb/10 gal water
Disinfectant, bleaching, and oxidizing agent.
(HTH)
Used for pesticides, fungicides, chlorinated
phenols, dioxins, cyanides, ammonia, and
other nonacidic inorganic wastes.
Hydrochloric acid
1 pt/10 gal water
Used for inorganic bases, alkali and caustic
wastes
Citric, tartaric,
4 lb/10 gal water
Used to clean heavy metal contamination.
and oxalic acids
(or their respective
salts)
Organic solvents
Concentrated
Used to clean equipment contaminated with
(e.g., acetone, metha-
organics or surface oils.
nol, methylene
chloride)
CURRENT PROTOCOLS FOR
Chemical neutralization methods
A number of chemicals can be used to neutral-
DECONTAMINATING
ize various organic contaminants. Although this
approach is not commonly used to decontaminate
SAMPLING DEVICES
sampling devices used for monitoring groundwa-
Commonly, guidelines for decontaminating
ter, the military has found this approach neces-
sampling devices (e.g., U.S. EPA 1992) suggest that
sary when decontaminating surfaces contaminat-
equipment be decontaminated by first washing
ed with neat chemical warfare agents. Moberly
with a nonphosphate detergent, then rinsing with
(1985) outlined a number of chemicals that could
tap water, rinsing with (high-quality) acids and
be used for decontaminating drilling equipment
solvents, rinsing with some type of high-quality
(Table 3). Bleaching agents include calcium hy-
water (e.g., distilled, deionized, organic-free re-
pochlorite (HTH), Super Tropical Bleach (STB),
agent water), and finally air drying. Washing with
and household bleach. Bleaches can degrade and
detergent and water removes gross contamina-
detoxify many of the more toxic contaminants,
tion and particles, an acid rinse desorbs inorganic
such as organo-phosphorus pesticides (Esposito
contaminants, a rinse with organic solvents re-
et al. 1985). Two problems with this type of ap-
moves less polar organic contaminants, and the
proach are that many of these decontaminants
final high-quality water rinse removes the acid
are hazardous to work with and they may de-
solutions and/or organic solvents.
grade the surface being decontaminated. For ex-
Almost all methods recommend either using a
ample, bleaches can corrode metal equipment.
nonphosphate (e.g., ASTM 1990, U.S. EPA 1992)
Thus, this approach is really only applicable for
or a laboratory detergent (e.g., U.S. EPA Region
extreme cases where one encounters high levels
of very toxic contaminants or where other clean-
IV 1991), or both. Although the surfactants used
in detergents can be cationic, anionic, amphoter-
ing methods have proven ineffective in reducing
ic, or nonionic, there has been little discussion of
contaminant levels.
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