Environmental Engineering Reference
In-Depth Information
kinds of operational diculties are obvious: establishing the cause and ef-
fect relationship with CSG extraction; the increasing infeasibility of making
good as the cumulative impacts of CSG extraction grow large with the in-
creasing number of wells across the landscape; and reconciling the long-
term impacts on aquifers, which are likely to play out on a time-scale of
many decades and perhaps centuries, with the much shorter time-scale of
CSG extraction.
There are reports from the Surat that Arrow Energy, a major CSG operator,
is delivering treated water in tanker trucks to farmers who have complained
of CSG-induced water shortages.
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This is economically feasible for a small
number of impacted livestock operations, but it also illustrates the limits of
making good inexpensively: this solution will become less feasible as more
farmers are affected and the travel distances become longer, and is obviously
infeasible if water for broad-acre irrigation is impacted.
3.2.1.2 Groundwater Contamination
Because CSG wells penetrate many geological layers and aquifers in order to
reach the coal seams, deterioration of the cement casing that lines the well
could allow cross-layer movements of contaminants.
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Ensuring well integ-
rity is therefore an essential element in managing potential contamination
of groundwater resources as a consequence of CSG operations. Stricter
standards for well preparation have improved well integrity in the last dec-
ade.
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Nevertheless, the potential impacts of CSG wells on groundwater ex-
tend for centuries, while the economic life of CSG wells lasts for only a few
decades at best, a situation that calls for rigorous inspection of wells, in-
cluding those no longer in use, and mitigation of any problems revealed by
inspection. Ideally such a program would be funded from sinking funds
established by the CSG operators, but no such arrangement exists currently.
This idea could be applied to environmental damage more broadly: a serious
case can be made for requiring CSG operators to post environmental bonds
consistent with the worst-case damage scenarios.
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3.2.1.3 Waste Water
The water co-produced in CSG extraction is briny to varying degrees and
contains a range of chemicals naturally present in and around the coal seam.
Depending on site conditions, these may include metals and radionuclides
that can be toxic to plants, animals and humans.
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The process of
fracking, where used, may add to the chemicals in waste water. While the
industry insists it is not presently using them, BTEX (benzene and similar
organic chemicals thought carcinogenic) chemicals have in the past been
added to the water. Volumes of 'produced' groundwater are typically large in
the early stages of CSG production, and the volumes of gas released are
small. However, later in the life of a well (which can be several decades) the
water produced decreases and methane production increases. Seams that
need fracking may produce less water than other seams.
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