862 PCBs AND ASSOCIATED AROMATICS
November 1, 1978: Federal Register 43 , 50905 (1978):
Interim rules-applications for exemption from PCB manu-
facturing ban.
December 20, 1978: Federal Register 43 , 59432 (1978):
List of approved PCB disposal facilities.1979February 16, 1979: Federal Register 44 , 10266 (1979):
Definition of “Discharge” under Clean Water Act.
February 16, 1979: Federal Register 44 , 10271 (1979):
Defines reportable quantities of PCBs spilled into water-
ways, reporting requirements and fines.
March 12, 1979: Federal Register 44 , 13575 (1979):
Request for comments on citizens’ petition to give Regional
Administrators authority to approve alternate disposal
methods.1981August 15, 1983: Versar report “Exposure Assessment
for Incidentally Produced PCBs: Appendix D: Prediction
of Human Exposure for Hydraulic and Heat Transfer
Authorized Uses:- The USEPA’s May 1979 regulation on PCBs,
entitled “Polychlorinated Biphenyls Manufacturing,
Processing, Distribution in Commerce, and Use
Prohibitions” (40CFR 761.30 Subpart B, Autho-
rizations), authorizes the use of PCBs until July 1,
1984, in hydraulic systems, in heat transfer systems,
for research and development (small quantities),
and as a microscopy mounting medium. - After discontinuing production of their heat trans-
fer oil in 1972 (Therminol), Monsanto notified all
known Therminol users that hazards were asso-
ciated with PCB use, offered to accept all fluid
drained from PCB-containing heat transfer sys-
tems, and suggested that systems be refilled with
non-PCB oil. Monsanto did not extend this ser-
vice to users of PCB hydraulic fluid (Pydraul). - Die casting hydraulic systems operate at high
temperatures and require a fire-resistant hydraulic
oil such as the type containing PCBs. PCBs have
also been used in other general hydraulic systems
(e.g., metal stamping equipment, forges, furnace
lid lifts, presses), although not as commonly as
in die casting hydraulic systems. It is likely that
the PCB contamination of many hydraulic sys-
tems results from the reuse and recycling of PCB-
containing hydraulic oils. - Releases to water from hydraulic systems: PCB
releases to water from hydraulic systems result from
leakage and draining of fluid. Individual hydraulic
systems are known to leak amounts of fluid equiva-
lent to 0.25 to 10 volumes annually. This amount
varies with machine age, maintenance, operating
pressure, and configuration (e.g., fluid lines, seals,
fittings). It is estimated that the average system
leaks at a rate of 2 volumes/year.- The leaked fluid recovery rate is the fraction of oil
that has leaked from hydraulic systems and has
been collected (typically with troughs or collec-
tion pans) and recycled into the system as topping
fluid. Estimates of fluid recovery range from 30%
to 80% for die casting systems and from 10%
to 50% for general hydraulic systems. Leaked
hydraulic fluid that is not recovered either volatil-
izes or seeps into the wastewater system. - The average fluid capacity of a die casting system
is 350 gallons; it is assumed that this is also the
average volume of a general hydraulic system. - The PCB regulations of May 1979 require that
hydraulic and heat transfer systems that have PCB
concentrations greater than 50 mg/Kg be drained
and resampled annually until the concentration is
reduced below 50 mg/Kg. - Approximately 20.3 million pounds of PCB-
containing heat transfer fluid was produced
between 1962 and 1972 in the US. - An average heat transfer system uses 400 gallons
of fluid and has an average leakage of 0.2 volumes
of fluid annually. - PCB releases of heat transfer systems to water:
PCB releases to water from heat transfer sys-
tems result from leakage and draining of fluid.
The leakage rates in typical heat transfer sys-
tems range from 0.05 to 0.7 equivalent volumes
of fluid annually. These rates are less than those
for typical hydraulic systems, since heat trans-
fer systems operate under less pressure, have
fewer external fluid lines, and do not perform
work on external components (pistons). A typi-
cal leak rate is 0.2 equivalent volumes of fluid
annually. Recovery of leaked heat transfer fluid
ranges from 20% to 40%: the average is esti-
mated to be 25%. Leaked heat transfer fluid that
is not recovered either volatilizes or seeps into
the wastewater system. - Occupational PCB air concentrations derived
from hydraulic systems: - Die casting systems have peak operating
temperatures of 100°C and average operat-
ing temperatures of 60°C. General hydraulic
systems have peak operating temperatures of
82°C and average operating temperatures of
52°C. Portions of some die casting systems
can have surface temperatures of 200°C. - Hydraulic systems leak continuously, cover-
ing the reservoir, fittings, hoses, and portions
of the machine and floor below with fluid.
These surfaces are therefore sources of vola-
tilized PCBs. The average hydraulic machine
has a 350-gallon reservoir with an appropriate
outer surface area of 6.2 m^2.
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