$4.($a$)$ Write the relationships among the maximum horizontal principal stress $(\backslash ($ S$\_\{$H m a x$\}\backslash )),$ the minimum horizontal principal stress $(\backslash ($ S$\_\{$h $\backslash$text $\{$ min $\}\}\backslash )),$ and the vertical stress $($Sv$)$ for $($i$)$ normal$/$strike$-$slip faulting, and $($ii$)$ strike$-$slip$/$reverse faulting.

$(6$ Marks$)$

$($b$)$ Hydrodynamic containment is to use or control groundwater to reduce or eliminate a stored product to escape through host rock. Describe horizontal curtain and vertical curtain that are used in hydrodynamic containment.

$(6$ Marks$)$

$($c$)$ What are the purposes of site investigation during underground excavation?

$(4$ Marks$)$