Mangaone Stream at Tremaine Ave Secant Pile Retaining Wall

⁠⁠⁠For the construction of a secant pile wall along the stopbanks of the Mangaone Stream.

The work includes but is not limited to

• Cut and fill earthworks for a temporary piling pad to allow for construction of the secant pile wall.
• Geotechnical investigation on the eastern bank upstream of the Tremaine Avenue Bridge as per Technical Specification Section 1.5.1.
• Installation of a secant pile wall on both sides of the stopbank downstream of the Tremaine Avenue Bridge, behind the existing gabion wall total wall length approx. 130 m as per drawings.
• Installation of a secant pile wall on the eastern bank upstream of the Tremaine Avenue Bridge. Estimated total wall length approx. 42 m as per drawings.
• Installation of capping beam on top of the retaining walls.
• Reinstatement of stopbank.
• Partial stream diversion.
• Removal of the existing gabions.
• Installation of colbond drains and shotcrete on the face of the pile wall.
• Excavation for and placement of rock armour at the base of the wall