Mangawhai Central: Five Years of Earthworks, Balanced
Coastal subdivision grading with geotechnical constraints
Mangawhai Central is a master-planned coastal development between Mangawhai village and Mangawhai Heads in New Zealand’s Kaipara District. Covering approximately 116–130 hectares, it connects existing community hubs between town and estuary.
Client Alvarium partnered with engineering consultancy Civix, using Level AI to design grading, roading and staged earthworks around complex geotechnical requirements.
The Challenge
A layer of peat just below the surface created a significant geotechnical constraint: excavating into it could increase building foundation costs. Civix needed to respect minimum levels, meet local road standards and manage cut and fill across multiple earthworks zones.
Tight delivery timeframes made fast, accurate iteration essential. The design had to balance successive earthworks stages without compromising the geotechnical constraints.
Technology in Action
Geotechnical points constrained the Level AI model around the peat layer and guided the surface design. The roading network followed local engineering rules, while TUFLOW flood modelling was performed through Allsite’s automations.
The Allsite web app produced drawings automatically. Level AI balanced five years of earthworks across more than 10 stages, with over 1,000 walls and slopes automatically generated and sized.
The Results
Civix delivered faster design turnarounds and explored more development options for Alvarium than with traditional manual CAD. The project combined five years of balanced earthworks, more than 10 earthworks stages and over 1,000 automatically sized walls and slopes.
Learn about Level AI for subdivision grading, read more civil engineering case studies, or discuss your earthworks project.
“Loading data into Level AI was easy even with complex geotechnical requirements and local rules. We could iterate quickly and generate grading models and plan sets ready for council.”
— Jermaine Vally
Principal , Civix