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St Mary’s Subdivision Case Study

Mako Civil Contracting Limited were awarded the head contract for a 19 lot (18 house lots) subdivision on the old St Mary’s Hospital Site in Onerahi. This project was a six-month contract to carry out the onsite earthworks followed by six-months of civil works to complete the subdivision.


This was a challenging site and the earthworks were carried out during a wet Northland winter, meaning that Mako Civil were one of a few contractors granted a winter works consent from the Northland Regional Council. The earthworks were completed to an extremely high standard nine weeks ahead of schedule and included:


  • Clearing site under the supervision of Iwi

  • Removal of contaminated asbestos material and contaminated soil

  • Cut and fill of 18 lots on steep areas with expansive clays and existing uncertified fill material with over 7,000m3 cut to waste and 1500m3 cut to fill

  • Erosion and sediment controls with DEB’s

  • Significant retaining including three palisade walls at a depth of 10m embedment and total length of 150m

  • Timber retaining wall at 71m 

  • Constructed 60m long by 2.5m high GAP65 geogrid batter


We worked closely with our subcontractor Leathwick Earthmoving to complete the palisade walls and timber retaining wall - Leathwick Earthmoving built these to specification with an extremely high standard of finish.


Following completion of the earthworks, Mako Civil moved onto the civil works component which included.


  • Three 25,000.00L buried stormwater attenuation tanks, five cesspits, 12 stormwater manholes ranging from 1050mm diameter to 1500mm diameter with connecting uPVC pipework ranging from 150mm to 375mm for a total distance of 260m. With gradients ranging from 1% to 30%.

  • Twelve wastewater manholes ranging from 1050mm diameter to 1200mm diameter with internal droppers and connecting 150mm uPVC pipework with gradients ranging from 1.5% to 27.5% for a total distance of 220m.

  • Engaging subcontractors for the installation of services to each lot consisting of power, water and fibre.

  • 233m of concrete pavement ranging from 4.5m to 9m in width.


All works were completed under NZS3910:2013 as a measure and value contract.


Mark and his teams’ skills and experience enables them to price, project manage and execute all components of earthworks and civil works including stormwater, wastewater and roading all covered by our comprehensive health and safety and environmental policy.


Throughout this project Mako Civil liaised with iwi, subcontractors and engineers, dealing with the neighbours and managing any issues as they arose, achieving the desired result for the client on time and under budget.



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Contact Mako Civil Contracting to discuss your commercial or residential earthworks and drainlaying requirements.

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