On an extensive tunnelling project, the Water Pollution Abatement Programme (WPAP) of Milwaukee, there is much vertical tunnelling or shaft sinking. Owing to the nature of the soft, water-bearing alluvial deposits, the use of dewatering, compressed air or caisson sinking was not considered practical. Cementation, winner of the most important shaft sinking contract of the programme employs ground
... [Show full abstract] freezing for shaft sinking, but has encountered a number of problems in employing this technique.