Environmental Engineering Reference
In-Depth Information
17.2.2.2
Soil and Water Contamination from CCA in Landfi ll
Some studies demonstrated the impact of CCA-treated wood disposed in landfi lls.
The leachate metals can pollute ground and surface water used for drinking
purposes as C&D (construction & demolition) landfi lls are unlined (Weber et al.
2002
). During rain, water penetrates into C&D landfi lls, causing leaching of wood
preservatives from disposed CCA-treated wood. Rainfall is the only cause of leachate
formation in these types of landfi lls for construction materials (Weber et al.
2002
).
On the other hand, Saxe et al. (
2007
) showed that aggregate groundwater data from
62 unlined C&D landfi ll sites and data from individual sites indicated no appreciable
arsenic migration to groundwater, despite an estimated 12.8 million kilograms of
arsenic disposal in CCA-treated wood in Florida by 2000. Nevertheless, there is
increasing concern about potential environmental contamination from leaching of
copper, chromium, and arsenic from treated wood in service and from wood
removed from service and placed in landfi lls in North America (Shalat et al.
2006
).
Arsenic is a major concern from a disposal point of view, with respect to ground-
water quality (Townsend et al.
2004
). The presence of arsenic in areas surrounding
CCA-pressure-treated wood poses a danger to groundwater contamination due to
runoff. Arsenic enters the environment and does not decay.
As the leachate of treated wood in landfi lls is genotoxic and carcinogenic, the
contaminated water is dangerous for human beings and animals. It is therefore
important to investigate leaching and biodegradation of treated wood. There is
the potential for soil, water and the environment to become contaminated with
chromium, copper and arsenic wherever chromium leaches least, despite being present
in the greatest proportion. A study investigating the effects of pH, temperature, and
duration of leaching showed in areas where the region is exposed to sulfuric acid rain
due to sulfur dioxide emissions that there is a high risk of chromium, copper and
arsenic leaching. Although most acidic rain has a pH of 4.3, the trend of decreasing
pH has shown to increase the leachability of wood. Moreover, as temperatures
increase, the amount of leached metals rises, arsenic in particular being the least
resistant to leaching (Moghaddam and Mulligan
2008
).
To assess whether landfi ll disposal of solid waste might impact leachate or
groundwater quality, a leaching test was conducted (Townsend et al.
2005
); the
results indicate that weathered, CCA-treated wood might result in elevated pollutant
concentrations in landfi ll leachates and possible groundwater impact at unlined
sites. Arsenic, chromium and copper were found to be above acceptable drinking
water standards and arsenic often leached above hazardous waste level limits.
CCA-treated wood storage requires soil lining particularly in the aftermath of
natural disasters to avoid affecting groundwater, particularly if disposed together
with construction and demolition (C&D) debris (Jambeck et al.
2008
). CCA in
construction debris proved to release more of its harmful elements when immersed
in water (Lebow and Tippie
2000
)
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