Surge pool EL (m)

Required Support

Grouting

Drainage Arrangement

Rock Bolts

Rock bolt spacing

Shotcrete

Crown

6 m long, 25 mm diameter resin end anchored cement grouted rock bolts (Fe415)

1500 mm c/c (staggered)

150 mm thick steel fibre reinforced shotcrete

Up to 6.5 m and spacing should be decided on the trial basis

6.5 m long 50 mm diameter drain hole @ 6000 mm c/c

Side walls

7 m long, 25 mm diameter resin end anchored cement grouted rock bolts (Fe415)

2000 mm c/c (staggered)

200 mm thick steel fibre reinforced shotcrete

Up to 7.5 m and spacing should be decided on the trial basis

7.5 m long 50 mm diameter drain hole @ 6000 mm c/c up to maximum surge level