Eastland Group has now closed the last of three damaged sluice gates at the Waihi hydroelectricity station, 26km north-west of Wairoa.
The 5MW hydroelectricity station on the Waihi River has been out of operation since late last year, following damage to sluice gates caused by extreme weather in September 2015.
The company’s chief executive, Matt Todd, says the company worked urgently to make repairs to the gates, which were damaged by severe weather in the last quarter of 2015.
“We quickly mobilised a professional team to the site to undertake work to fix the gates. That team was working seven days a week, and had nearly completed work on the first of the three gates, when the Hawkes Bay Regional Council asked us to provide an independent engineering report.”
The report concluded that essentially the same work needed to be recommenced and completed.
On Monday, 15 February, Eastland Group received resource consent from HBRC to recommence works to repair the damaged sluice gates at Waihi Dam.
“Since then we have been working around the clock to repair the gates and get the dam operational again. With the gates closed since 9.20pm last night, the reservoir is now filling. When the required level is reached – possibly Sunday or Monday with rain forecast over Easter – the intake tunnel and penstocks feeding the power house will be filled and operation of the generators recommissioned.”
Mr Todd paid tribute to the team of engineers, divers and other contractors working alongside Eastland Group staff to ensure the repairs were completed safely.
“These guys have been working in incredibly challenging conditions, often underwater. They have been away from their families for many weeks now. Excavation and removal of sediment immediately downstream of the dam gates is continuing but will be suspended for the coming weekend so off-site maintenance can be undertaken on specialist equipment and the team can enjoy the Easter break at home.”
However, the work on site is not over, says Mr Todd.
“Eastland Group will work closely with HBRC to develop plans for the future management of the dam. We will need to confirm the safety integrity of the dam by test opening the gates in the near future. The proposed methodology to carry out this activity is yet to be discussed with the council.”
The Waihi dam is part of the Waihi hydroelectricity scheme, generating enough power for 1600 homes, and has been owned by Eastland Group for 17 years. It was built by Wairoa Electric Power Board in 1986. The three sluice gates are essential for the safe operation of the hydro-electricity scheme. These gates sit at the base of the dam and are designed to release water during high inflows and release sediment or debris built up behind the gates. The purpose of the sluice gates (as their name suggests) is to sluice away sediment build-up. The sluice gates are somewhat unusual because they are at the bottom of the dam and entirely underwater, which makes access difficult.