Stopbank

Boulcott Hutt Stopbank

Construction of 1.7km of stopbank including bulk earthworks, drainage, flood walls, retaining walls, roading realignment, fencing and finishing. Work included moving the stopbank and increasing the size of the stopbank using river run from the Hutt River, existing material and imported material.  It also involved moving and/or reconstructing the stopbank through the live Boulcott Farms Heritage Golf Course.

Earthworks

  • Approximately 175,000m3 of fill placement including imported fill from Belmont Quarry, fill from the Hutt River and cut to fill from existing stopbank material
  • Approximately 70,000m2 of topsoil strip and respread
  • River run extracted from the river by digger dumper operation – involved multiple river crossings
  • Goodmans negotiated with and then self performed the extraction from Belmont Quarry

Roading

  • Realignment of Connolly Street involving reconstructing stopbank, completing road realignment works, new drainage lines across the road, and constructing flood & retaining walls all while keeping the busy road open to the public.

Clearing

  • All clearing including felling large quantities of old man pine trees and pruned pine up to 1m in diameter.

Concrete Work

  • Construction of various flood walls, retaining walls and path walls – work by Work done by Wallace Construction

Erosion & Sediment Control

  • GWRC requirements were met
  • Work was within the flood plain so controls were silt fencing and temporary grit traps
  • Strict noise, vibration, and dust restrictions had to be met.
  • Cyanobacteria strategy in place.

Drainage

  • Stormwater drainage including large headwalls, flap gates, flood gates and ancillary drainage.
  • 225mm diameter road sumps up to 750mm diameter stormwater lines.
  • Drainage lines down to 4m in depth.

Traffic Management

  • Level 1 road with annual average daily traffic AADT of 8,500 with peak between 8-9am and 4.30-5.30pm. Traffic management completed by Goodmans.

General Comments

  • Very public site. Had to manage many pedestrians on a daily basis.
  • Houses close to worksite – 52 properties within 75m and 17 properties within 10m of the toe of the stopbank.
  • School close to worksite
  • Large section of the stopbank was constructed on the live Boulcott Farms Heritage Golf Course
  • Very strict Notice of Requirement conditions enforced through the Resource Consent process including detailed noise and vibration considerations and plans.
  • Work involved constant monitoring of river levels, especially in rain events
  • Melling substation adjacent to the worksite meant we had a large number of high voltage services to contend with.

Relationships

  • The collaboration was very important on this contract. GWRC was the main client and Hutt City Council were the asset owner for road and drainage.
  • Boulcott Farms Heritage Golf Course had to operate while work occurred on the golf course.
  • Transpower and Safeway were two affected neighbouring properties.
  • 69 private residences within 75m of the toe of the new stopbank.

 

  

 

Strand Park Stopbank

Bulk earthworks, drainage and flood walls for work involved in rebuilding an existing stopbank.  Work included moving the stopbank over, and increasing the size of the stopbank using river run from the Hutt River, existing material and imported material.

Earthworks

  • Approximately 49,000m3 of fill placement including 20,000m3 imported fill, and the remainder cut to fill from the river and from existing stopbank material
  • Approximately 20,000m2 of topsoil strip and respread
  • River run extracted from the river by motorscrapers
  • Involved working in the river flow

Clearing

  • Removal and treatment of large area of bamboo
  • Removal of large Pohutukawa trees

Concrete Work

  • Construction of various flood walls, retaining walls and path walls Work done by Juno Civil
  • Management by Goodmans

Erosion & Sediment Control

  • GWRC requirements were met
  • Work was within the flood plain so controls were silt fencing and temporary grit traps

Drainage

  • Stormwater drainage including pipes, sumps, manholes, culverts, flapgates, penstocks etc.
  • Large outlet culvert installations. Culverts 750 and 900 diameter.  Run in lengths of 100m+.
  • Drainage done below watertable and below level of river
  • Dewatering required

Demolition

  • Demolition of concrete toilet block.

General Comments

  • Very public site. Had to manage many pedestrians on a daily basis.
  • Houses close to worksite
  • Kindergartens close to worksite
  • Hutt Valley High School close to worksite
  • Work involved constant monitoring of river levels, especially in rain events