Leak repairs for Arapuni canal

Press, 16 July 1983, Page 6

Leak repairs for Arapuni canal

PA Rotorua Another hydro scheme built on central North Island volcanic land — the Arapuni power station 55km up the Waikato River from Hamilton — is giving trouble, and leak repairs are being planned. The Arapuni scheme, the first Government-built station on the Waikato, was commissioned in 1929, but

there was a big leakage soon after, similar to that which recently occurred at the Wheao and Ruahihi dams, and the dam had to be closed for 18 months. During this time the scheme’s canal was lined. It is this lining which has malfunctioned recently. But the Electricity Division of the Ministry of Energy says there is no urgency or immediate danger from the leaking canal. Repair work, which will include draining the 15 sq. km Lake Arapuni, may not be done for three or four years. The district manager, Mr P. W. P. Chapman, said yesterday that the bitumen and concrete slab linking which was used in the early 1930 s to line the 400 m-long canal was giving out. But the full extent of deterioration could not be

ascertained until the lake was drained and engineers could investigate. Ministry of Works and Development engineers went to Arapuni last year when monitored drainage canals under the headrace showed a sudden jump in flow.

Mr Chapman said that minor repair work had been able, to stem the flow, but Ministry experts were still anxious to do a full repair job on Arapuni. He said the problem for his Ministry was finding a time when Arapuni could be taken out of action, thus lowering the combined storage capacity of hydro lakes on the Waikato River. Relining the Arapuni power station’s headrace will be a big job, costing about ?8 million.