Disposal of low-level radioactive and toxic industrial wastes in dissolved
caverns in salt deposits represents a safe, practical and economically feas
ible alternative to current waste management practices. Disposal in solutio
ned caverns in salt strata can provide environmental security over geologic
time (> 10(5) yr) because salt caverns will slowly close onto the solid wa
stes, isolating them from the formation fluid flow systems. Because this me
thod is permanent (non-retrievable), ensuring the long-term isolation of th
e wastes from biosphere interaction is fundamental to this technology. Perm
anent secure isolation can be achieved by choosing appropriate disposal sit
es, and by properly engineering a waste slurry which will compact over time
when subjected to the stresses of a closing cavern.
This article discusses engineered waste slurries designed to address the to
xicity level of candidate waste materials. Issues related to site selection
criteria,site investigation techniques, and decommissioning strategies are
also discussed. Some experimental results showing how porosity reduction o
ccurs in compacting slurries is presented. Salt cavern disposal is technica
lly founded on petroleum engineering, geology, hydrogeology, rock mechanics
and geochemistry. Suitable salt deposits are almost always found in sedime
ntary basins where petroleum development exists; therefore, salt cavern dis
posal for toxic oil field wastes is a natural application.