CEMP - NZ Transport Agency

NZ Transport Agency
CSM2 & MSRFL
It is anticipated that there will be approximately 85,000m³ of excavated (cut to waste) material that
is deemed unsuitable for construction. For the most part, this material will be disposed of on site,
reducing haulage distances.
1.3.6 Bridges and retaining walls
The construction of the nine bridges and associated retaining walls for the interchanges, overpasses
and underpasses will be a significant part of the Project. Bridge components such as deck beams
(both concrete and steel) will be manufactured in a controlled environment at an off-site facility.
Other components will be cast in-situ using local ready mixed concrete providers. Both piled and
spread footing bridge foundations will be used, with piles likely be either bored concrete or H-steel
sections.
1.3.7 Utilities
There are several utilities that will need relocation, amendment or protection throughout the
project. Each utility provider has been consulted to understand the various requirements and
limitations in the local area that may impact relocation or protection of the services. These include:
• Transpower’s Islington to Springston 66 kV transmission lines to the southwest of the
Shands Road and Marshs Road intersection where the alignment falls within the
transmission line clearance envelope;
• Orion’s overhead electricity supply network;
• Chorus and Telstra Clear telecommunications networks;
• Water supply and wastewater disposal networks;
• Water Races.
The necessary written approvals and agreements to enable the works will need to be obtained at a
future stage, where required.
1.3.8 Stormwater
Surface water will be dealt with differently in the MSRFL and CSM2 alignments. Main South Road
and the adjacent rail embankment have impediments to overland flows, and they have little
stormwater infrastructure in place. The widening of Main South Road will have little impact on the
current behaviour of the catchment. Therefore, isolated soak pits in the low lying areas are
proposed, with allowances for potential over topping.
For the CSM2 section at low points in the topography of the area, the surface water flood flows will
pass underneath the motorway using a series of siphons. Bunds will protect the roadside swales
and dispersal points. The additional disposal areas at locations of concentrated overland flows will
provide protection to the road against flooding. Stockwater races will be passed under the
motorway via a siphon system, typically measuring between 300mm and 450mm.
There are nine existing stockwater races, two along MSRFL and seven along CSM2, noting that a
stockwater race runs parallel to MSRFL on the South Eastern side within the road reserve for
approximately 2100m. These will be subject to alterations, including crossings under the
Draft 11 CEMP