2. Mangatawa catchment consents for earthworks, storm water ...

NZ Transport Agency and Tauranga City Council
Mangatawa Drain Flood Bypass and TEM Stormwater AEE
into the drain performance. They produced three reports 1 and the last was after the May 2005 floods. As part
of their work a MIKE11 hydraulic model was built. New Zealand Transport Agency (NZTA) has been working
with TCC to find a solution which will avoid or at least reduce overflows. The aim for NZTA was to avoid if
practicable the 1% annual exceedance probability (AEP) storm event overtopping and overflowing the
motorway, while TCC’s aim was to reduce the volume of water that would enter the Papamoa catchment areas
(Maranui Swale and the Wairakei Stream) such that the design flood level for Papamoa of 4.5m RL (Moturiki
Datum), as defined in the District Plan, was not exceeded in the 2% AEP storm event. Beca was appointed to
adopt the Opus hydraulic model and undertake further modelling and engineering work to investigate
mitigation options, as an extension to the work they were carrying out for NZTA on the TEM.
2.4 Existing Statutory Approvals
Currently there are no resource consents for the management of stormwater generated by State Highway 2 or
for the Mangatawa drain discharge to the Tauranga Harbour. However the Mangatawa Drain is defined as
Land Drainage canal in the Regional Water and Land Plan 2 .
The TCC treatment wetland that receives stormwater from the Maranui catchment has consent for discharge
which needs to be varied as part of this application.
The over spill into the Wairakei catchment is currently covered by the Wairakei Catchment comprehensive
consent which is currently subject to appeal.
2.4.1 TEM Designations previously gained by New Zealand Transport Agency
The designated corridor for the motorway has been in place since 2004 and was designated in four parts. It
consists of designations for:
• Te Maunga Four Laning
• Te Maunga Service Roads
• Sandhurst Interchange
• Tauranga Eastern Arterial.
The designations are now collectively referred to as the TEM. The designations that relate to this project area
are Te Maunga four laning and Sandhurst Interchange.
1 Mangatawa Drain Flood Capacity, September 2000; Mangatawa Drain Flood Capacity: Supplementary Report, July 2001;
and Mangatawa Drain Flood Assessment, 29 November 2006; all produced by Opus International Consultants Ltd
2 RWLP Dec 2002, Definitions Chapter, Pg 436. Land Drainage Canal.
Status: Final Page 5 April 2009
Project Number: 3932036
NZ1-1552092-Mangatawa Drain Flood Bypass and TEM Stormwater AEE