Burkes Drain Flood Management 

Client:  Horizons Regional Council

Completion: November 2014

The location of the site is on Highway 56, approximately three kilometres southwest of the Highway 56/SH56 intersection south of Palmerston North.  The contract was for the design and construction of a pump station with a capacity of 7.5m³/s.

This Pump Station was constructed on the bank of Burkes Drain, 200m from the Manawatu River.  Excavation work was 14 meters deep, some 3 meters below the invert of Burkes Drain.  The structure was 21 meters long, 10 meters wide and 6 meters high, consisting of insitu and precast concrete construction, a large concrete 9m x 6m x 3m surge chamber to control the water discharge was also included in the scope.  Twin 1350 RCRRJ pipelines led the water flow 1050 meters downstream from the Pump Station.

The construction process was accelerated by the innovative use of precast reinforced concrete slabs, which were delivered to the site by truck from the precast works. The wet well base slab was site cast, with the wet well walls, roof and internal pump inlet bays being constructed from precast post tensioned concrete slabs; which were subsequently placed by crane and joined with site cast stitch joints. The discharge pipes were cut through the stop bank, which was then reconstructed with a filter collar around the new pipelines to mitigate the risk of a piping failure in the embankment when the Manawatu River is in flood. The construction included some significant earthworks with deep excavations being constructed to house the wet well base slab and the dual reinforced concrete 1350mm ID outlet pipes Four 1900L/sec Xylem pumps were installed to cut in on various scenarios regulated by the river levels and flows in Burkes Drain.