Stormwater
Introduction |
About stormwater |
Solving stormwater problems |
Growth and stormwater |
What Auckland City is doing |
Stormwater projects near you |
Stormwater assets |
Stormwater guidelines and other documents |
Educational information
Stormwater projects near you
Some problems need community solutions, like flooding or pollutants from
motor vehicles. Because we all use roads, Auckland City needs to provide
publicly-funded stormwater infrastructure to remove these pollutants before they
get into our waters.
Engineered wetlands are one solution - and at the same time as cleaning up
stormwater, they can help to reduce flooding while providing habitat for native
plants, birds and fish.
Resource consents are often required for stormwater projects. People affected
by the projects are consulted before the resource consents are granted.
Abbotts Way
Ellerslie's Abbotts Way is a busy stretch of road servicing a large
residential population, as well as popular recreation spots such as Waiaturua
Reserve, Ellerslie Racecourse and Remuera golf course.
Under the Getting on with it stormwater upgrades initiative, the
Abbotts Way stormwater upgrade projects seeks to reduce flooding in the
Ellerslie/Green area and ensure the future proofing of the area to meet
development needs.
Works will be carried out on both the lower and upper parts of Abbotts Way,
with the lower portion of Abbotts Way involving open cut work, with the digging
of trenches. Works on upper Abbotts Way will be trenchless with all work carried
out underground.
The target completion date for the Abbotts Way stormwater upgrade is May
2009.
Brady Road landfill
The former Brady Road landfill in Otahuhu is near the Tamaki River. To
minimise the potential for contaminants to reach the River, in 2001 a five year
programme was initiated to remediate the landfill at a cost of $3 million.
Features include:
- capping the landfill to reduce the infiltration and the production of
leachate
- swales that direct stormwater to a coarse sediment trap and treatment
wetland
- extensive riparian planting: combined with other revegetation, over 15,000
native plants have been established
- a seawall to protect against erosion.
CBD
stormwater outfalls
Over the past decade, Auckland City has revamped the stormwater system in the
CBD. At a cost of approximately $40 million, old combined sewers have been
replaced by dedicated stormwater pipes, and a series of old outfalls replaced
with new major outfalls at Wynyard and Captain Cook wharves. Under an agreement
with Ports of Auckland, the stormwater-borne sediment deposited at these
outfalls is being dredged and disposed to landfills.
Ahead of its use as the America's Cup base from 1998, particular attention
was paid to the Viaduct Basin. This formerly run-down area is now an
international showcase, with stormwater diversions, screening and sewer
separation making a big difference to the water quality of one of the city's
most popular attractions.
Lumsden Green
Newmarket has been identified as an area problematic for flooding, in
particular the area of Lumsden Green and Davis Crescent, with the little
drainage infrastructure currently in place unable to sustain the growth
the area has experienced.
Under the Getting on with it stormwater upgrades initiative,
the Lumsden Green stormwater upgrade project seeks to solve the problem
of flooding in the area, while providing waste and stormwater separation
and ensuring the future proofing of the area to meet development needs.
The project is scheduled to begin June 2008, and continue for
approximately 32 weeks. It is a technically challenging project
involving the sinking of a 30m shaft prior to underground tunnelling in
the directions of Broadway and Kingdon Street.
Lumsden Green will be closed for public access over this time, with hoardings
placed around the site, restricting public access.
Martyn Wilson reserve
Auckland City Council proposes to create a stormwater pond in the south-west
corner of Martyn Wilson Reserve, which will impound water from the existing
Remuera Stream, allowing sediment to settle, while slowly releasing the
stormwater downstream. This will improve the quality of water discharged into
the Waitemata.
Auckland City Council would like your feedback on the proposed stormwater
pond and it's place in Martyn Wilson Reserve.
To give your opinion download, print and complete the
Martyn Wilson Reserve feedback form
(PDF 73kb) and send to:
Auckland City Council
Martyn Wilson Reserve Upgrade
Freepost 215924
C/O Andrew Stewart Ltd
P.O Box 911310, Victoria St West
Auckland 1142.
Motions pipeline
The Motions Creek catchment is 456 hectares of commercial and residential
development serviced by a complex network of separate stormwater and combined
wastewater and stormwater drainage systems. In wet weather, pipe capacity is
frequently exceeded, resulting in isolated cases of flooding of habitable
floors. Flooding hotspots centre around Ivanhoe Road, along the north-western
motorway corridor and the commercial area of Nikau Street, Shaddock Street and
Boston Road.
A new Motions Creek stormwater main
extending from Western Springs Park to Normanby Road in the upper catchment,
will augment the capacity of the existing stormwater system, protecting
habitable floors from flooding up to the 100 year rainfall event. The project
was given the green light when a comprehensive catchment consent was issued in
2000. Following design work, construction began in 2001 and is expected to be
complete by 2006/7, at a cost of about $25 million. Key features of the project
include:
- the large pipe diameters - up to 3m
- the innovative underground controlled blasting approach used to excavate
through volcanic rock at Western Springs
- the use of a sophisticated 2.5m diameter tunnel boring machine.
New Oranga Community Centre, Fergusson Park
The new Oranga Community Centre is off Waitangi Road, Onehunga, in an area of
where stormwater disposal is by soakage. The facility is a demonstration project
for on-site stormwater soakage devices designed in accordance with the soakage design manual. The stormwater
treatment and disposal system incorporates a series of swales, rain gardens and
soakholes, with educational signs showing how they work.
New Wesley Community Centre
The new Wesley Community Centre is on the corner of Sandringham Road and
Gifford Avenue, with a new building close to Sandringham Road together with car
parking and outdoor space areas. The Oakley Creek is a major feature of the site
and stormwater stormwater runoff from the site goes into it.
The facility is a demonstration project for on-site stormwater management
devices designed in accordance with the city's new on-site
stormwater management manual. The chosen design incorporates a series of five rain
gardens and two catchpit filters designed to treat site runoff, with educational
signs showing how they work.
Rain falling on the roof and paved areas of the community centre is
channelled through either a series of five rain gardens or a catchpit filter
before flowing into Oakley Creek.
Omaru Creek stormwater treatment pond
The Omaru Creek drains through Glen Innes to the Tamaki Estuary at Point
England. In order to reduce the level of stormwater-borne contaminants reaching
the estuary to one-quarter of the pre-project quantity, Auckland City constructed a
stormwater treatment pond in Waitoki Reserve. The on-stream pond, which includes
extensive native plantings, was constructed over the period 2001-2002 at a
cost of $400,000.
Orakei Basin
Orakei Basin, next to Hobson Bay, was created in its present form in the
1930s with gates maintaining the water level at about the normal high tide
level. It is an important recreational asset, best known for water skiing, but
also as a place to swim and walk the margins. Over the years catchments
draining into the basin, including the outlet from the Waiatarua wetland, have
deposited sediment in the basin including contaminants which can be harmful to
marine life. In 1999 Auckland City embarked on a programme to dredge some 150-200mm of sediment out of the shallower areas of the basin. Over a period of 3
years, 21,000 tonnes of sediments were removed and disposed of at landfills at a
cost of about $2.5 million.
A key feature of the dredging exercise was the innovative method used,
developed through initial pilot trial with a contractor. The water was too
shallow to use a conventional suction dredge, and it would have required the
dredgings to be dewatered by expensive centrifuging. Instead, a digger mounted
on a barge deposited dredgings in breeze boats. Once full, the boats were towed
four at a time across to the jetty where a crane lifted each boat up and tipped
its contents into a waiting truck for secure landfilling.
Parnell
Flood hazard assessment showed that flooding is a risk in the low-lying areas
of The Strand, Ronayne Street and Parnell Rise. As part of Auckland City's
ongoing programme to reduce stormwater flooding problems in Parnell, a $2.6
million stormwater project took place over a 16-week period from April to July
2005. This involved constructing one of the largest stormwater systems in
Auckland City by lifting precast concrete sections weighing 14 tonnes each into
a large trench.
Auckland City's drainage upgrade in the catchment area will eventually lead to a
new outfall in the port to further help to reduce this flood risk
Stanley Bay pipeline
Auckland City worked closely with Transit New Zealand and its consultants in
the planning for the State Highway 16 extension down Grafton Gully and on to the
Port. The planned duplication of the under-sized pipeline along
Stanley Street (from Grafton Road and into The Strand), was brought forward to
ensure that the works were completed in time to allow the motorway construction
to proceed unimpeded. The project involved 600 metres of pipeline, and was
constructed over the period 2002-2004. It is estimated to have saved $0.5
million by only needing to dig once to do both jobs at the same time. Future
stages will duplicate the lower part of the system and construct a new
stormwater outfall.
Waiatarua wetland
The Waiatarua Reserve receives stormwater from a 570 hectare catchment in the
Greenlane / Ellerslie area, including flows fed by a tunnel under Ladies Mile. It
also receives water pumped from the former Mt Wellington quarry. In its former
state, the channels and small pond at the outlet served to settle out some
sediment, but had become overgrown. In exploring remedial options as part of a
catchment management planning exercise in the 1990's, Auckland City saw potential to
construct a major wetland facility at Waiatarua. This would intercept the bulk
of the incoming sediment and prevent it from reaching the Orakei Basin, a prime
recreational asset.
Construction of the new wetland and associated facilities began in 2002, with
the main physical works substantially completed in May 2004. Key features
include:
- a 16 hectare wetland
- forebays on the main waterways entering the reserve, designed to let
coarser sediment settle, making it easier to remove before it reaches the
main wetland
- planting of the wetland margins with native species, covering 20 hectares
- development of habitat to encourage birdlife, including sanctuary areas
- a series of new walkways.
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