Risk management of chemicals and contaminated land – from planning to verification - Environmental Deterioration and Contamination: Problems and their Management - page 232

simply summarize them. It is easy only in theory because one encounters huge prob-
lems when trying to monetize the value of nature and man in different regions and
countries.
Technological efficiency is the most objective characteristic of a technology
including environmental technologies for air, water, or soil treatment. Efficiency of
technologies in general can be measured by the quality and quantity of the products.
Environmental technologies can be characterized by the removal, disposal, transfor-
mation, stabilization, or degradation of the contaminant or the reduction in the adverse
effects due to decontamination of air, water, or soil. It can be measured in the course of
technology application using chemical analysis or biotesting. Technological efficiency
can be calculated by setting the mass balance of the contaminants in the contaminated
media from measured masses and fluxes or by other indirect effects of the technology
such as the decrease in the toxic or other adverse effects. The measured concentrations,
flows and adverse effects are compared with the initial ones and efficiency is calculated
and given as a percentage decrease. Another possibility is to compare the results of the
technology to a reference or a case-specific target and express the end point data in the
percentage of the target value.
Environmental efficiency is a complex issue and should be adapted to the scale,
quality, and sensitivity of the environment. Management options, RA methods, and
RR technologies can be evaluated based on their local, regional, and global impacts
on humans and ecosystems over the short and long term. A soil remediation technol-
ogy, for example, has a local environmental impact and reduces the environmental
risk through the removal of a volatile and water-soluble contaminant from the soil.
Environmental efficiency calculation includes the decrease of the risk posed by the con-
taminant in the local soil, but the risk by a water-soluble contaminant should also be
evaluated in the surface water, maybe in the whole watershed downstream. A volatile
or dusting contaminant may disperse in the atmosphere through long-distance trans-
port allowing the contaminant to reach the ozone layer in the stratosphere causing
ozone depletion.
Summing up, positive impacts of the remediation technology should be aggre-
gated with the negative impacts on material and energy consumption and resource
depletion, as well as the emissions caused by the technology, for example, off-gases
or heat contributing to local or watershed-scale water contamination and air pollu-
tion. In addition, due to an in situ technology one has to expect local disturbances in
the soil environment resulting in uncontrolled mobilization or transformation of the
contaminants. The aggregated positive and negative impacts can be compared with
the alternatives or the references evaluated in a similar way. Most of the failures in
environmental efficiency evaluation are due to an improper concept and an incomplete
inventory of risk compartments selected for evaluation. Another difficulty is the aggre-
gation of the individual risk components; environmental risks can be quantitatively
evaluated one by one and their acceptability is judged accordingly, but when the issue
is to sum them up, they need a synthesizing, analogous scale generally having relative
units: percentages or scores. This is a suitable approach to compare alternatives but it
cannot be copied for decision making. Decision making requires objective (quantita-
tive) results which show if risk is negligible or not. Whether or not risk is acceptable is a
relative issue: it is acceptable when social and economic benefits override the potential
damages. It should be left to decision makers to judge.