1

Length of surge pool with approach for ventilation

200 + 25 m

2

Excavated width of cavern (B)

20.20 m

3

Clear width of cavern

20.00 m

4

Crown level

250.25 m

5

Spring level

240.00 m

6

Surge pit level

181.50 m

7

Height of surge pit wall

58.50 m

8

Height of overburden above crown (H)

70.75 (average)

9

Ground levels maximum and minimum above crown

321 m and 319 m

10

Rise of arc

10.25 m

11

Unit weight of rock (γ)

2.60 t/m³

12

Average spacing of joints

0.750 m

13

Maximum upsurge level

239.9 m

14

Minimum downsurge level

214.8 m

15

Thickness of concrete lined bottom portion

300 mm

16

Rock ledge between old and new surge pool

100 m