soft soil 
pa or sediments 
~ 
y 
~ 
S7. 
= 
\z 
JZ 
Z 
WY) 
NS 
(a) 
initial large 
diameter bore hole 
Note: Deep hole bored by machine, 
a, is used for spoil deposit for 
later lateral excavation, b. 
critical seal area 
to complex 
spoil from 
lateral excavation 
Figure 58. Method for spoil removal from living complex. 
Note: 
water 
q 
NZIS 
carbide cutters ys 
rotate 
steel cylinder 
casing to be cemented in place to act as guide for 
further boring by large mole type of machine. 
Figure 59. Method for using steel casing with carbide cutters for cutting through 
sediments to bedrock. 
73 
