Sealing of boreholes and underground excavations has not received much engineering attention until fairly recently. The growing awareness of and sensitivity to environmental concerns of the technical community as well as of the public at large has resulted in an increasing recognition of the fact that these geological penetrations may have an environmental impact. The issue of possible contamination resulting from migration along boreholes, adits, shafts or tunnels unquestionably has been raised most forcefully with in the context of nuclear waste disposal. Several nuclear waste disposal...