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LIUDD Case Studies – Tamaki
Tamaki, catalyst project
This case study includes four sites in the 'Tamaki edge' area – Tamaki Landcare Research building, Talbot Park (updated October 2007), NZ Netball courts, Mt Wellington quarry – that have aspects of low impact approaches incorporated into their design and development.
Talbot Park, NZ Netball courts, and Mt Wellington quarry are brownfield sites in the process of development and include some LIUDD approaches, such as on-site storm water management (raintanks, raingardens, swales, porous paving).
Case study work involves showcasing the technical, ecological, economic and social learnings from these brownfield sites at site and device scales.
Stormwater mitigation is planned around the construction of approximately 50 stormwater ponds across the catchment in the middle and lower catchment. The ponds are intended to slowly release water into the original waterways at the same rate as before the development. Waterways are to be retained within environmental corridors, with natural borders retained in order to contain a 100-year flood.
Maps showing locations of case study areas
Landcare Research Tamaki building
The Landcare Research building (follow link for more information), situated in the Tamaki Campus of The University of Auckland, was designed and built using cost-effective low-impact technologies that utilise natural systems and sustainable design.
We aim to maximise opportunities to share the learnings from this site, including evaluation and monitoring of the technical, ecological, economic efficiency (e.g. measuring the actual energy savings, effectiveness of ventilation systems, reduction in waste water and sewage, and the success of our on-site stormwater management system). We will also be assessing the impact of the building’s design on the health and well-being of staff working in the building.
This part of the catalyst project focuses on:
- Best practice in New Zealand
- Commercial building
- Porous paving – Swale – Raingarden – Raintanks – Water recycling
Before-and-after shots of vegetated swale at Tamaki building
Raingarden at entrance to Tamaki building
Talbot Park
- Retrofit
- High-density urban
- Signs – Porous paving – Raingardens – Swales – Raintanks
Talbot Park is a Housing New Zealand Corporation (HNZC) development in Glen Innes, Auckland which has undergone a $48 million community renewal project. This project was launched in October 2002 and completed in March 2007, and was aimed at creating an improved living environment for tenants. The number of homes in Talbot Park has increased from 167 to 219, 111 of which are new homes (increased from 550 to 750 residents). The existing nine Starblocks (3 storey apartment blocks) have been internally refitted. Site areas have been redeveloped based on Crime Prevention Through Environmental Design (CPTED) principles, including visibility fences, a new car park, landscaping and security lighting.
Low impact urban design and development (LIUDD) features have been integrated into the development, including on-site stormwater management devices, and solar panels. On-site stormwater management devices, including rain gardens, rain tanks first flush devices and porous paving, are aimed at mitigating the effects of increased stormwater flows and contamination loads created by the development. Narrow carriageways and traffic calming devices have also been used to improve walkability.
LIUDD devices at Talbot Park were made possible by a grant from Infrastructure Auckland (IA). HNZC aim to use the site to demonstrate and monitor LIUDD devices to increase public acceptance and reduce costs of incorporating similar devices into future development. The site therefore provides a good opportunity to evaluate social, economic, technical, and environmental performance of the devices. The rain gardens (n.14) are of particular interest as they are the first to be installed on public roads in Auckland city. Lessons learned in planning and implementation of the rain gardens to achieve optimal performance are documented in this case study, together with learnings related to other devices.
Rain gardens:
Rain gardens were constructed around the roads at Talbot Park prior to housing construction and were completed with landscaping in January 2006. ACC required the rain gardens to be built prior to building construction as they were part of roading construction required prior to building consents being allocated. Permeability rates were measured by ARC upon completion and determined that they were performing according to specifications. However, curb and channel edging of the rain gardens which was installed to keep cars off, prevented sheet flow of water to the rain gardens, instead concentrating water at a few entry points. This flow concentration was exacerbated by having slightly raised parking areas, which meant water generally flowed into rain gardens through only one or two points. Curbing was modified to allow improved water flow from the roads into the rain garden.
Rain gardens were designed to help slow traffic and provide visual amenity to Talbot Park, as well as detain and treat road runoff. Evergreen magnolias and native groundcovers of sedge, mountain flax and NZ iris were planted. Photo: May 2006, soon after construction.
Constructing buildings after rain gardens led to many rain gardens becoming clogged with sediment runoff from the building sites (up to 20 cm of deposition) and compaction of the substrate by contractors parking or dumping waste construction materials on the rain gardens. Sediment from building sites also blocked some entry points, preventing stormwater from flowing into some rain gardens (see photo below). Nevertheless, the rain gardens performed a useful function of reducing sediment discharges into the piped stormwater system during the construction phase of the development. Signs and contractor induction may be useful to inform people of the purpose and requirements of rain gardens.
Landcare Research scientists examined the rain gardens several times in 2006 and found that some of the gardens were working reasonably well. Infiltration testing of two rain gardens in September 2006 confirmed they exceeded ARC (2003) permeability guidelines of 300 mm per day. However, because they were overfilled with mulch and soil, they were unlikely to meet ARC (2003) live storage guidelines of 220 mm. It was also observed that the accumulation layer of silt, sand and debris did not appear to slow down infiltration. Recommendations were made for improving landscaping aspects of the rain gardens, including lowering the rain garden surface to meet the 220 mm live storage guidelines (or the height of the SW grates raised using a concrete collar) and replacing mulch with a thinner (c.50 mm depth), non-floating organic mulch. Phormuim (mountain flax) and Carex (sedge) cultivars have generally performed well, with high survival rates and acceptable growth rates (photo). Muelenbeckia and Libertia have died in nearly all rain gardens, showing a lower tolerance to sediment accumulation, compaction/treading damage and anaerobic conditions that developed within the rooting zone (under the mulch and accumulated sediment) in parts of many gardens.
HNZC expressed keen interest in refitting the rain gardens that were not performing well. ARC also required this before IA funding could be released to HNZC. However, HNZC wanted agreement on what should be done to the rain gardens by all interested parties. Stakeholders (HNZC, ARC, ACC, Boffa Miskell and Landcare Research) then met in September 2006 to discuss the best course of action. Boffa Miskell was engaged to draw up plans for the redevelopments required, and these plans are now awaiting approval by ARC (June 2007).
During construction of houses, sediment eroded from the building sites was captured in some rain gardens until it prevented water flowing into the rain gardens (left photo, July 2006). Most rain gardens were constructed with less than the specified 220 mm ponding depth, generally due to a combination of overfilling of the raingarden with soil and mulch, and the overflow grates being set too low. This means in places stormwater can short-circuit the raingarden, reducing treatment efficiency and volume detained (photo July 2007).
Permeable paving:
HNZC planned to use permeable paving extensively in Talbot Park on driveways, patio area and pathways. However, they had problems finding a suitable permeable paving product, some having very hard sharp surfaces and therefore unsuitable for areas where children play. The need for ongoing maintenance was also a deterrent, and the lack of a contractor specialised in this maintenance.
A small amount of permeable paving has been installed around 4 x 1-bedroom accessible units. A new permeable paving product (PermaPave) and a stormwater treatment tank have also been installed at the Atrium apartments to assist in filtering sheet water from the large carparking area.
Rain tanks:
Rain tanks have been installed in 4 terrace homes, 4 x 1-bedroom accessible units and in 1 large apartment block. The tanks installed for the terrace homes and units are small (3500 litres), half of what was originally planned, because it was decided that space in the small backyards (>50m2) needed to be retained for tenant use. The system is a dual water supply system, with rain tank water used for toilets and outdoor taps, reticulated water for the rest of the house. A larger 50,000 litre tank has been installed underground at the Atrium apartment block to service 24 units. Signs have been erected next to outdoor taps to warn that the water is not drinkable.
Other:
Solar Panels have been installed in 4 x 1-bedroom accessible units.
Starblock refits included the replacement of all services (electrical and plumbing), installation of passive ventilation around existing windows and mechanical ventilation in bathrooms and kitchens in all but one block (the first block they renovated they did not install these and learnt from that the need for these devices). Balconies have also been added.
Operation & Maintenance:
HNZC is responsible for maintaining the rain gardens for the first two years. ACC formally took over ownership as an asset on public roads as of April 2006, and will take over management of the rain gardens as of April-2008.
Operation of rain tanks requires some tenant involvement and so education has been required. If rain tanks run dry, tenants can switch over to mains for toilet flushing and outdoor water use, but need to switch back to tank water once it rains. Maintenance of water pumps and permeable paving will be HNZC’s responsibility.
What worked well?
- Accessing funding from IA as part of a collaborative proposal.
- Stable and committed leadership in HNZC project management team (project manager and project co-ordinator) over the term of the project.
- Engaging residents in decisions related to designing and implementation of community renewal.
- The use of rain gardens for stormwater treatment, traffic calming and amenity on public roads.
- Using 8 different architectural firms to design the new homes, and 1 for an overall masterplan, leading to a range of housing styles.
What were the challenges?
- Gaining consent from council roading engineers for rain gardens in public roads.
- Requirement to construct rain gardens on public roads prior to redevelopment of housing sites, leading to rain gardens becoming clogged with sediment from building sites and damaged by compaction and squashing – leading to death of most groundcover plants.
- Ensuring that rain gardens are constructed to design specifications, particularly ensuring overflows are high enough to allow 220 mm ponding depth and perform efficiently.
- Sourcing a suitable permeable paving product.
- Tenants are required to take responsibility in the operation of the dual water supply system but are not required to pay water bills.
- Requirement for dual water supply system reduced economic viability of the water system.
- Council requirement to provide one park per home, but this level of parking space is under-utilised and unnecessary.
Recommendations:
Rain gardens: Allow live storage of 220 mm. Sheet flow is required for rain gardens to function well; barriers can be pinned above the ground as an alternative to curb and channelling. Rain gardens should be completed after buildings. If raingarden underdrains and gravel/sand layers are completed before buildings are started, they can be covered with filter cloth, and used to trap sediment during construction. After houses are finished, this filter cloth and overlying sediment should be removed and raingarden tilled, planted, and mulched. Rain gardens should be mulched with a non-floating organic mulch (e.g., long-fibre chip). Signs can be useful to inform people about the purpose and requirements of the rain gardens (photo).
New Zealand Netball courts
- Brownfield development
- Quarry site into sportsground
- Raingarden – Swales
Proposed netball courts in relation to Tamaki building
Mt Wellington Quarry
- Large brownfield development
- Water-sensitive urban design
Recent Publications
Bracey S, Scott K, Simcock R. 2008.
Important lessons applying low-impact urban design: Talbot Park.
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In: Proceedings of NZWWA conference 15-16 May, Royal Lakeside Novotel, Rotorua 2008.
Contacts
 | Kathryn Scott Email  |
Landcare Research | |
Phone: +64 9 574 4100 | |
| Details: Kathryn Scott |