This article was written by Richard Silcock and originally published in the June edition of Contractor Magazine. It is republished with permission.
Rotorua City’s lakefront is undergoing a $40 million redevelopment that will provide an outstanding recreational facility for the benefit of the local community and tourists. Richard Silcock reports.
Plans for the redevelopment of Rotorua City’s lakefront had been on the drawing board since 2006. However due to a lack of funding it was not until last year and an input of $19.9 million from MBIE’s Provincial Growth Fund together with $20.1 million from the Rotorua Lakes Council that the project was able to progress, with the redevelopment being split over a number of stages.
The Council’s general manager strategy and development, Jean-Paul Gaston says: “This redevelopment will reflect Rotorua’s unique attributes and become a feature of the lakefront.
“During the design process we worked closely with the Isthmus Group, local iwi (Ngati Whakaue and the Te Arawa Lakes Trust) and other key stakeholders to establish clear guidelines for the protection of the lake’s water quality, relocation of the native koura habitat and to ensure the design reflects in a modern way the cultural heritage and history of the area,” says Jean-Paul.
“The western end will provide for boating and water sports, while the eastern end will be a more contemplative relaxing space where the natural beauty of the area can be enjoyed.”
The first stages of the project involve earthworks, realignment of the lake edge, construction of a boardwalk along the lake frontage, terracing for people to sit and the upgrading of underground utility services.
The curved timber boardwalk will stretch almost the entire width of the lakefront and pass over both the lake and the foreshore, following the original shoreline and affording panoramic views of Lake Rotorua and Mokoia Island.
Bridges representing waka drawn up on the shore will provide access to the boardwalk. There will be six of these bridges, each incorporating iwi inspired story-telling artworks.
HEB Construction was awarded the contract for the $16.8 million first stage last October and started physical works at the end of January following extensive in-situ ground stabilisation tests and trials.
Project manager for HEB, Cole Meiring, says the team working on the project is excited to be involved in this iconic redevelopment along the lakefront.
“Prior to the Covid-19 level 4 lockdown in late March we were able to construct a coffer dam by driving 800, 12-metre-long sheet piles some six to 10 metres into the lakebed and then pump out the water behind to create a comparatively dry construction area,” says Cole.
“This has a health and safety aspect for our team and also helps to stop sediment runoff into the lake. Once the project is complete the piles will be removed, allowing the lake water to return.
“We then excavated the previously reclaimed land, realigned the lake edge to its natural original contour and with the help of GSI Contractors carried out ground stabilisation with a special mixer attached to an excavator. Over 6000 cubic metres of grout slurry was used.
“Work for the five metre wide, 300 metre long timber boardwalk, which will sit half-a-metre above the lake water level commenced following our return to work. It will sit on a series of mini concrete piles that are being driven three metres deep into 150 millimetre diametre drilled foundation holes filled with quick setting grout.
“The timber for the boardwalk itself will be constructed using tonka hardwood imported from Peru. This has been specified due to its strength and durability in the corrosive volcanic environment.
“The six bridges (tukutuku) will vary in width and length, with some up to 30 metres long and will connect the foreshore to the boardwalk and jut out beyond it. They will be constructed of concrete, clad in tonka hardwood and feature local Maori design motifs.”
The design also includes a series of terraces, stepped up the lakefront in 300 to 600 millimetre increments and constructed using rough cast concrete to mimic the surrounding volcanic landscape.
Waiotahi Contractors has been contracted for the underground utility services, which comprise the upgrading of the existing stormwater and sewer pipes along with a large water main junction.
Area manager for Waiotahi in the Bay of Plenty, Dennis Curtiss says they are also preparing the foundations for a large new toilet block.
“The toilet block site required excavating a metre of top soil, compaction and filling using locally sourced quarried pumice rock.
“The main part of our work covers an area of approximately five hectares where we are excavating and installing the stormwater and sewer pipes, along with inspection manholes.
“As we are working close to the lake edge the water table is only 1.5 metres below ground level, making excavation work a bit of a challenge, so we are deploying a number of soakage devices along with dewatering and pumping out to holding ponds under special RMA consents.
“We are ensuring the ‘Mauri of the Wai’ is reinjected into the whenua and placed back in the water table,” says Dennis.
“The geothermal activity in the area also adds to the complexity of the job with the ground temperature reaching 60 degrees centigrade in some areas of the project.
“While most of the team had to cease work under the Covid-19 level 4 lockdown period, we were deemed an essential service as the sewer and stormwater network connects to the nearby public hospital, so we maintained regular inspections to ensure the integrity of the lines over the five week shut down period.”
The next stage will include preparing the ground in readiness for a new carpark and a greatly enlarged sports playing area, construction of the new public toilet block and the streetscaping and widening of Tutanekai Street at its northern (lake) end.
Red paving stones from an original walkway have been carefully removed and will be recycled for use in the footpaths.
The Council’s operations group manager, Jocelyn Mikaere, says the project is being constructed in stages for a number of reasons.
“In order for parts of the lakefront reserve to remain accessible to the public during construction, multiple stages and differing contracts were required.
“Additionally, resource constraints prevented a sole contractor from delivering all of the work and as the nature of the work varies from stage to stage, different skill sets have been required,” says Jocelyn.
“It has also allowed for better cost control and enabled us to spread the work around and give various local parties input to the project.”
Other stages will include a veranda walkway, further terracing work and the upgrading of the commercial area to the west of the lakefront where restaurants, cafes, a visitor iSite and other facilities will be established. A function centre may also be included in the future.
Isthmus Group landscape architect, Travis McGee says the completed redevelopment will help to reconnect people to the lake, provide recreational and socialising areas, honour the intrinsic beauty of the area and celebrate the lake’s historical importance in Maori culture.
The entire project is scheduled to be completed by early 2023.
Footnote: Income from visitor spend in Rotorua amounted to $1300 million last year, with $800 million coming from New Zealanders and $500 million from international visitors. However it is likely that visitor numbers will be severely impacted by the Covid-19 pandemic this year.