Horseshoe Lake Reserve is a popular recreational area in North East Christchurch, managed by Christchurch City Council. The lake is a wāhi taonga, or site of significance, to local Māori and the surrounding wetland area has ecological importance, playing a critical role in the drainage of the northern part of Christchurch. The area suffered considerable damage during the Canterbury Earthquake Sequence with much of the reserve unsafe and unusable to the public.
As part of the council’s earthquake response they wanted to repair and regenerate the reserve, creating a safe park that could accommodate a larger number of visitors. Their goal was to modernise the reserve with refreshed planting, better parking, and more mobility access, enhancing the area and making it more accessible for visitors.
The council initially needed an expert geotechnical assessment of land damaged in the earthquakes. The ground had suffered natural spread, damaging a public access footbridge and car park. The car park needed to be relocated and redeveloped to accommodate the number of visitors to the area. As our senior geotechnical engineer started working with the council the project grew and with each new requirement we provided the expertise needed to keep the project moving forward.
Areas of the reserve are over a capped landfill with maximum excavation levels in place to minimise disturbance of the landfill cap and prevent release of contaminated material into the waterways and surround land. The area is also an area of special cultural significance and an ecologically sensitive zone with recorded inanga spawning that required specific planting and ecological considerations.
The council wanted to restore the existing footbridge in place, but it soon became apparent the groundworks need for this to happen would be prohibitively expensive. At this stage our structural engineering team got involved to design a new accessible bridge through an alternative, planted area of the reserve. We also designed a rockery across the stream in place of the bridge to provide another pedestrian accessway and create a point of interest that was both cost effective and designed in sympathy with the landscape.
The relocation and redevelopment of the car park required careful planning from our civil and infrastructure and geotechnical engineers as it was to be built over the landfill area. We designed a solution that minimised the excavation needed and ensured there was no disturbance of contaminated ground or need for disposal of contaminated material. The optimised design ensured ecological safety and avoided any costly earthworks or contamination remediation for the client.
Our landscape architecture team worked closely with our 3 waters engineers to design a stormwater management system that was both functional, aesthetically pleasing, and appropriate for a recreational reserve. The ecological considerations and capped landfill in parts of the site meant no planting that required deep excavation, such as tree pits, were possible. Plant species that had shallow root systems or did not required deep excavation were carefully selected and planted in areas where they wouldn’t be damaged by any stormwater runoff or would disturb the landfill cap.
The council wanted to make the whole site accessible. The accessways and paths throughout the reserve were designed to work with the maximum excavation depths and additional picnic tables with accessible designs were added.
We worked closely with the council’s in-house project manager. This was a community project and the designs were presented to community meetings for feedback before being developed further. We became the council’s partner through the whole project, providing on demand response across all disciplines from the design and consenting process through to engineering and compliance monitoring during construction.
Interdisciplinary communications were essential for the success of this project. Our internal project manager could understand the complexities across the whole project and marshalled all the key specialities within our team, giving our client a single point of contact to manage the project through to completion.