Contract Details
Contract ValueNAIndustryHydroelectricityCompletionOngoingContract DurationMulti-yearProject Overview
Arapuni Hydro Power Station is situated in a gorge of the Waikato River, surrounded on both sides by steep banks and cliffs. Several years ago, a slip on the riverbank released a significant amount of material into the tail race. This presented two problems for our client
- Dam owners are required to maintain unimpeded flow through the tail race.
- The slip threatened in time to undercut the only access road to the powerhouse.
Considering these risks, a multi-year effort has been underway to both reduce the deposit of material obstructing the tail race, to stabilise and protect the bank and road from further erosion.
Project Description
This last week saw the execution of another stage; the protection of the lower toe of the slope with a concrete ‘seawall.’ This wall was to be built on the riverbed in the approximate location of the old riverbank. However, building a wall of concrete in a riverbed comes with many risks and restrictions.
During this time of the build Mercury had a station shut scheduled to last up to 34 hours that would lower the water level below the work site. Avalon scheduled two teams:
- Team One - was tasked with the construction of boxing and drainage.
- Team Two - supported by Waikato Concrete Pumping was tasked with the delivery and placing of concrete to the wall.
With 1 hour to spare, 44.4m3 of concrete was placed between the front rows of the wall proper, and the backfilling of the lower level to seal ready for future backfilling of drainage material.