Geoenvironment Impact Mitigation and Management - Sustainable Practices in Geoenvironmental Engineering - page 359

earthquake-resistant design of constructed facilities, lood control dykes and embank-
ments, avoidance of earthquake zones and other natural geo-disaster zones or regions,
etc. To be considered a geo-disaster, one needs to make a distinction between (a) a disaster
that happens to an above-ground facility due solely to failure of the facility itself as a result
of impacts from stressors, and (b) failure of the above-ground facility due to failure of the
ground to provide durable support. The latter disaster is considered a geo-disaster. Most
of the types of stressors involved in the preceding natural geo-disaster types are gener-
ally mechanical and hydraulic. Civil (structural, hydraulic, and geotechnical) engineer-
ing capabilities have developed technology that will respond to the need for protection
against these types of geo-disasters.
Ground improvement is one of the techniques used to provide stable supporting plat-
forms and competent soil capable of resisting excessive ground motion under mechani-
cal and hydraulic stressors. In addition to the more traditional geotechnical engineering
methods for ground improvement, a new innovative and sustainable method for ground
improvement has recently been developed. This will be discussed in detail in Chapter 12.
10.3.1.2 Anthropogenic Actions
A major group of geo-disasters occurring as a result of anthropogenic actions are chemi-
cal in nature, as has been demonstrated in the previous chapters, more often than not
resulting in threats to the health of biotic receptors. Inadequate or deicient foundation
or subgrade or soil stability considerations under mechanical and/or hydraulic stressors,
leading to ground failure, constitute another group. The means for mitigating or counter-
ing stressor impacts for this second group are similar to those mentioned in the previous
subsection discussion relating to natural events .
By and large, a signiicant proportion of geo-disasters of a chemical nature are really geo-
hazards, i.e., they present threats to the health of biotic receptors and also to the geoenvi-
ronment. In most instances, the line separating geo-hazards from geo-disasters is a function
of several factors: (a) a matter of scale (size and intensity), (b) direct consequence and level
of threat (toxicity, lethality, harm, exposure), (c) magnitude of physical and geoenviron-
mental damage, and (d) economic consequence. Geo-hazards and/or geo-disasters involv-
ing chemicals, in one form or another, occur as a result of
• Source control : Inadequate or insuficient measures of control of plant operations
involving fugitive and planned discharges in operational processes. Mitigation of
stressor impacts consist of corrective action by management to reduce or eliminate
chemical stressors and their sources and to install or implement capture and treat
systems, i.e., systems to capture fugitive and planned discharges for treatment
prior to inal discharge from the plant.
• Direct application of chemical aids : Use of chemical aids (a) for control of pests and
unwanted plant species (e.g., pesticides, herbicides, fungicides, insecticides,
etc.) and (b) as soil amendments (fertilizers) or as control agents (e.g., deicing
compounds). These direct actions give rise to non-point source contamination
of the soil and receiving waters. Mitigation of stressor impacts for contami-
nants in the soil consists of reduction or elimination of chemical stressor toxic-
ity (concentration and toxic level) before the contaminant reaches any biotic
receptor. This is the subject of discussion in the rest of this chapter and the next
chapter.