Projects

MAP Projects was engaged by Rotorua Lakes Council in October 2022 to undertake the building of two flood detention dams in the Upper Kaipakau Stream catchment to reduce the potential occurrence, extent and impacts of flooding on nearby properties and roads. It also included the establishment of a stormwater treatment wetland.

The project involved the construction of two detention dams (East and West Dams 700m apart) and the treatment wetland. The two dams were built concurrently with MAP crews working on both sites at the same time. This has involved detailed resource scheduling and allocation to ensure production efficiencies across all the phases.

Earthworks for the two dams and wetland included 100,000m3 cut to waste and 100,000m3 of dam fill. The dam fill was comprised of a variety of specified materials for each zone of the dam structure construction with the majority won from the site borrow areas, conditioned and placed as per the specifications. Specialist filter materials for chimney and blanket drains were imported with comprehensive procurement.

The Primary Spillway for the West Dam was 43m of Class 4 2100 dia. concrete pipe and 60m of 2000 dia. HDPE pipe including 300m3 of concrete encasement. The Primary Spillway for the East Dam was 44m of Class 4 1800 dia. Concrete pipe and 60m of 1800 dia. HDPE pipe, again with 300m3 of concrete encasement.
The Auxiliary Spillway for the West Dam has ended up at 700m3 of reinforced concrete for the chutes, wall, floors etc and the East Dam Auxiliary Spillway 150m3 of reinforced concrete.

Other works across the project have included new stormwater and sewer lines and manholes, piezometer and settlement instrumentation installation, large wing wall outlet and inlet structures with over 500m3 of rock rip rap.

This project was very challenging, but in a combined effort with Tonkin and Taylor, we have produced an outstanding project that will stand the test of time and enable future development to continue in the area.