The geotechnical and environmental aspects of heap leaching are
very closely tied during design, operations and closure. Potential
environmental impacts from heap leaching are mostly due to land
disturbance and water quality issues, including both groundwater
and surface water. Water quality issues are mostly related to
containment design, which is primarily a function of proper
sizing of the facilities and site specific liner design. Geotechnical
analyses is the dominant discipline in providing cost efficient,
operationally effective and environmentally sound heap leach
facility designs. Much has been published on geotechnical aspects of heap
leach design, for example Van Zyl, Hutchison and Kiel (1988)
and Van Zyl (1987). This paper will emphasize a few specific
aspects related to the geotechnical and environmental
consideration for heap leach projects. These aspects are: site investigation; containment design;
slope stability; heap flow dynamics; and
closure design. Design of a heap leach project must consider not only the
operating life but also closure and post-closure considerations.
As a matter of standard practice, designing for closure is an
extremely important concept. Not only is it important for
environmental aspects, but experience also shows that projects
designed for closure will be overall more economical for the total
life cycle of the project. Closure considerations are also
important during project feasibility evaluations to ensure that
total life cycle costs are evaluated.