Recent Superfund sites have seen increased costs of
remediation, lower cleanup thresholds for concentrations of contaminants of
concern (COCs), and the identification of atypical COCs in stormwater. These developments
have resulted in some departments of transportation (DOTs) being identified as potentially
responsible parties (PRPs), when they would not typically have been included
five to ten years ago. For example, the Oregon Department of Transportation (ODOT),
the Washington Department of Transportation (WSDOT), and the California
Department of Transportation (CalTrans) have all been designated as PRPs at
sediment cleanup sites in their respective states. Also, a study found PCBs in
paint used on bridges by Minnesota Department of Transportation (MnDOT).
Low cleanup thresholds lead to a review of all potential
sources of sediment contamination, including stormwater. Sediment cleanups costs
are in part rising due to the increased complexity of controls required by
regulators. Additionally, sediment remediation projects have become
larger in terms of geographic extent, volume, complexity, expense, and duration.
This is in part due to a more sophisticated approach to sediment
projects because of advanced
site investigation techniques and more detailed analysis of source control, recontamination, and bioavailability, amongst other things.
These more sophisticated approaches and further evaluation
of source control and recontamination have identified the need to examine
atypical COCs in stormwater. For examples, based on findings of recent studies of
contamination in stormwater, the identification of newly-revealed sources has
shifted the emphasis from polycyclic aromatic hydrocarbons (PAHs) and zinc to polychlorinated
biphenyls (PCBs) and phthalates.
Initial research has identified two sources of PCBs in
paints used as coatings on bridges and/or road paints:
added to paint as a plasticizer (1940s to 1979): The use of PCBs in the
paint and coating industry reportedly began in the 1940s (Martin
2009). PCBs were added for the
o Increased adhesion
o Increased luster
o Reduced drying time
o Corrosion resistance
o Good heat and humidity resistance
o Increased antifungal properties
to the enforcement of the U.S. Environmental Protection Agency (EPA) regulation
40CFR761 (Polychlorinated Biphenyls [PCBs] Manufacturing, Processing,
Distribution, Commerce, and Use Prohibitions), PCBs were manufactured and used
in the U.S., including as an additive to paints. The manufacture of PCBs was
ceased by its sole U.S. manufacturer in 1977, and the sale or use of PCBs in
non-closed systems (such as paint applications) was banned in the U.S. on May
31, 1979 (Hess et al. 2001; Martin and Richards 2009; EPA 1979, 13; EPA 2014, 1,
10; EIP Associates 1997, 1–3).
However, PCBs in coating products purchased prior to 1979 could have been used after
1979, and PCB-containing coatings applied to bridges prior to 1979 had the
potential to leach into the environment after 1979.
produced in certain pigments: Pigments produced after 1979 have been
determined to inadvertently contain PCBs due to the manufacturing process. In a
2010 sampling event, PCB concentrations in modern coating products ranged from
2 to 200 ng/g in 15 of 33 sampled coating products. Pigments identified as
containing PCBs from these sources included azo (yellow/red) and phthalocyanide
(blue/green) pigments (Hu and Hornbuckle 2010,
WSDOT-LDW 61001041 at WSDOT-LDW 61001041–045).
the potential environmental hazards, PCBs in old paint have the potential to
pose an exposure risk to workers during paint removal by abrasive blasting.