Geoenvironment Impact Mitigation and Management - Sustainable Practices in Geoenvironmental Engineering - page 397

affected site or region. If total removal of all contaminants is not an option, minimization
of the risk posed by the presence of the contaminants is the next priority. This latter course
can take several forms. The basic factors to be considered include
• Contaminants : Type, concentration, and distribution in the ground
• Site : Site-speciicities, i.e., location, site constraints, substrate soil material, lithogra-
phy, stratigraphy, geology, hydrogeology, luid transmission properties, etc.
• Economics and risks : Cost-effectiveness, timing, and risk management
The techniques that can be considered fall into ive groups: (1) physicochemical, (2) bio-
logical, (3) thermal, (4) electrical-acoustic-magnetic, and (5) combination. Physicochemical
techniques rely on physical and/or chemical procedures for removal of the contaminants.
These include precipitation, desorption, soil washing, ion exchange, lotation, air strip-
ping, vapor and vacuum extraction, demulsiication, solidiication, stabilization, reverse
osmosis, etc.
Biological techniques are generally used to treat organic chemicals, but as we have
pointed out previously, these can also be used for remediation of heavy metal contami-
nated sites. The techniques used include bacterial degradation and/or transformation,
biological detoxiication, aeration, fermentation, and biorestauration. Thermal procedures
include vitriication, closed-loop detoxiication, thermal ixation, pyrolysis, super critical
oxidation, etc. Electrical-acoustic-magnetic methods include electrochemical oxidation,
electrokinetics, electrocoagulation, ultrasonic, and electroacoustics. Finally, the last group
that speciies combination implies that any of the four previous groups may be combined
in a series-type technical solution to provide the necessary remediation-treatment. This is
sometimes called a treatment train.
Remediation of contaminated sites is a very large challenge that offers innumerable
opportunities for technological innovation. The basic means for treatment given in the
preceding paragraph have been used in many different technologically clever ways to
effect remediation of contaminated sites. The reader is advised to consult specialized
manuals and textbooks devoted exclusively to remediation and treatment of contaminated
sites. Bioremediation occupies perhaps the greatest attention of most researchers and prac-
titioners attending to remediation. Much research is being conducted and reported in the
various specialized journals.
10.11 Concluding Remarks
Geoenvironment impact mitigation requires one to have information not only on the
kinds of stressors responsible for the impacts, but also on the nature of their effects on the
land compartment of the geoenvironment (which is the subject of interest of this topic).
Although mitigation of stressor impacts is a necessary requirement and goal in protection
of the health of biotic receptors and the geoenvironment, impacted site restoration is also
another pressing issue that needs to be addressed. To do so, it is irst necessary to deter-
mine the goals of site restoration, i.e., the type of site functionality that restoration should
achieve. Determination of site functionality requires attention to the kinds of attributes
and indicators required.