Several landfill sites in Florida are
experiencing elevated iron concentrations in the groundwater wells. The iron rich soil is being hypothesized
as source of iron. Similarly the
disposal of arsenic treated wood in unlined C&D landfills is a concern
for potential groundwater contamination due to arsenic (As) leaching from
the wood. The two issues are
interrelated since changes to the redox conditions can have a strong impact
on the fate of both As and Fe. The
fate of As is very much tied to chemistry of iron; iron soils have a strong
ability to adsorb arsenic from water.
The fact that reducing condition under landfills may cause iron to
be released suggests that As will also be released and might be more mobile
than expected based on soil properties alone.
The primary objectives of this project
are to quantify the contribution that soils beneath landfills can make to
iron in groundwater and to evaluate the ability of soils beneath C&D
debris landfills to retain and hold arsenic against leaching. Elevated iron concentrations have been
noted at a growing number of facilities in the state, both lined and
unlined, but the source of the iron is unknown. This study will attempt to relate the
chemical, physical, and hydrologic properties of these soils to their iron
releasing potential. The second
issue is the fate of As from CCA-treated wood at C&D debris
landfills. The ability of soils to
retain arsenic depends on the chemical and physical properties of the soil
as well as the chemical properties of the surrounding solution, such as
redox potential and presence of organic and inorganic ligands. These factors will be quantified to the
extent possible and utilized in an existing transport model to evaluate the
leaching potential of arsenic beneath C&D Landfills.
