Protect existing and new function centre.


  • This historic and popular tavern is positioned at the top of a large riverbank.
  • The riverbank rises several meters above the river below.
  • A substantial slip threatened the opening of the new function centre.

Challenges met:

  • Respected and established working relationship with Auckland Council.
  • EDC responded with a solid, tied-back timber wall design within 24hrs.
  • Access was achieved from above rather than from the river.



Stream rehabilitation and bank retaining.


  • Variable soils and soft ground.
  • Active stream.
  • Geotech investigations not done by EDC.

Challenges met:

  • Rapid geotech investigation.
  • Designs considered on site constructability.
  • Ongoing rapid response monitoring.


Inspection of Rock Bolts supporting a Swing Bridge in the Te Urewera National Park.


  • Location deep in the Ureweras.
  • Difficult to test the Anchors.

Challenges met:

  • Travel by 4WD vehicle fording rivers and then by foot..
  • Engineering Geologist observed the location of the anchors and made visual assessment of rock.
  • Engineering Geologist also observed the surrounding cliff faces to search for an alternate location.


  • Steep section.
  • Irregular weathering profile of underlying rock and soils presented difficult foundation conditions.

Challenges met:

  • 7m Gabion retaining wall (welded mesh panels) built to support slope at rear of building platform.

EDC’s experienced Geotechnical team responded quickly, the end result was a substantial, attractive and well-engineered retaining wall providing the client with peace of mind.

A retaining wall design was required along the boundary for this multi-lot development.  EDC worked with the developer to establish the most suitable wall type for their project and then identify a low vibration installation method in order to minimise the risk of damage to adjacent property and also alleviate concerns being raised by nearby residents during installation.

EDC produced a design package for the wall and carried out inspections during construction to ensure compliance.

Using the most up to date methods of assessment, EDC identified a high liquefaction risk in the shallow soils of this site.  We identified driven piling as the most economical foundation solution for this multi-unit Housing New Zealand development.  A pile design was produced by EDC’s geotechnical team who were proactive in leading the client through the process of a piling contract to completion using a foundation method that they had not previously used.

Structural and civil design is also being provided by EDC, providing the benefit of an efficient and coherent approach to the client.

The site is located close to a river in an area of liquefiable soils and thus required a robust assessment of potential liquefaction related ground movement and a foundation solution to suit the assessment outcome and proposed retail building. The site had tight space constraints for the investigation. EDC worked with the client and landowner to ensure that sufficient on-site works could be undertaken. A piled solution was adopted to support the concrete ground floor of the retail building and EDC undertook all structural design works, which included Glulam beams, floor and columns.  Lateral loads were resisted by plywood shear walls and diagonal steel Reidbar.

The site is located in an area affected by liquefiable soils with a shallow ground water depth. The proposed buildings for Canterbury Rugby Football Union are long structures that could be prone to differential settlements.

EDC undertook the geotechnical investigation and then worked closely with the design team and contractor to design a shallow ground improvement that ensured robustness and buildability through avoidance of excavation into the ground water table.  EDC then supervised and monitored the shallow ground improvement works to confirm that a first class product was constructed for the next installment of Rugby Park’s history.

EDC’s collaborative working added value to the construction of this high profile project through a proactive role in communication and sound engineering input with the design team and contractor.

EDC provided a geotechnical assessment for an Importance Level 4 upgrade to a rural substation. The works involved a combination of test pits, boreholes, hand testing and percolation testing to enable soak pit design.  EDC provided detailed input to assist the structural design team to ensure that the substation will withstand the rigours of the New Zealand environment.

The development of a former industrial storage yard for residential purposes seemed to be too difficult for many developers until Horncastle Homes took up the challenge in 2015.

EDC provided innovative Environmental and Geotechnical Engineering solutions to the site constraints, providing subsequent design and supervision that effectively remediated and strengthened the ground for residential living.

The project has recently been completed and there are now 26 houses for Canterbury families to live in on what was barren land for more than a decade.

EDC provided geotechnical and structural engineering services for the temporary housing to assist flood affected residents in Whakatane. The development consisted of 20 temporary cabin structures based at the Whakatane Holiday Park.

With the clock ticking, and accommodation urgently needed for those displaced by the floods, our Whakatane based geotechnical team swung into action and carried out the site works to confirm the ground conditions and provide recommendation on foundation design. With the baton passed, our structural engineers designed a cheap and simple to construct timber foundation that could resist the very high lateral spreading expected at the site, and accept the new portable units. Complex ground conditions need quality design solutions. EDC geotechnical and structural engineers worked together to develop a great solution under immense time pressure.

EDC’s geotechnical assessment highlighted this site to be on soils prone to liquefaction. Owing to the significant depth to non-liquefiable soils, and with guidance from EDC, the client opted to mitigate the liquefaction risk to foundations using deep stone column ground improvement. EDC’s geotechnical team provided ground improvement design and added value through assisting with contractor selection. A contractor with a low-vibration column installation method was chosen, avoiding the potential for damage and concern at neighbouring properties. Installation works were supervised and validated by EDC, to the regulator’s satisfaction, using CPT’s and seismic cross hole testing.

Synergy was provided through EDC also undertaking structural design, providing a robust but economical foundation and superstructure design.

EDC welcomed the opportunity to build on our previous early learning centre work through providing our client with valuable high-level geotechnical advice when assessing the feasibility of this site for the proposed building. The EDC geotech team’s subsequent holistic analysis of the liquefaction and other geotechnical risks resulted in our recommendation of a bespoke gravel raft ground improvement and foundation system becoming reality. We liaised closely with the client and structural engineers, providing a smooth process with minimal clarifications requested from Council.

The result was unity between the client objectives of compliance, robustness and construction cost viability, and ultimately an awesome building for future generations to navigate their early years.

  • Geotechnical: Riverhead Tavern, Riverhead



  • Geotechnical: Brick Bay Drive, Sandspit

  • Geotechnical: Jellicoe Street, Christchurch

  • Geotechnical: Bealey Avenue, Christchurch

  • Geotechnical: Piko Wholefoods, Christchurch

  • Geotechnical: Rugby Park, Christchurch

  • Geotechnical: Centre Bush, Southland

  • Geotechnical: Edgeware, Christchurch

  • Temporary Housing - Whakatane

  • Geotechnical: BestStart, Barrington, Christchurch

  • Geotechnical: BestStart, St Martins, Christchurch