Tunnels in the left abutment of Marun dam… Tunnel Diameter Cross-section Length Lining Diversion tunnel #1(DT1) 11m Horse shoe 494m 60cm Access tunnel to the crest 6.5m Horse shoe 404m Unlined Access tunnel to the gate chamber 7.5m Horse shoe 538m Unlined Bottom outlet 6m Circular 494m Steel & concrete 60-80cm Pressure tunnel 3.5m Circular 396m Steel and concrete 60-80cm Diversion tunnel #2 (DT2) 13m Circular 683m Unlined