Education - Stormwater
 

Please feel free to contact and talk to EcoWater Solutions' education staff. They work with primary and secondary schools on a wide range of water projects and their services are free within Waitakere City. They also provide information for individuals and community groups.

The education team can do the following for teachers:

• provide a visiting speaker for your class who arrives with hands-on activities
• supply student-friendly resource material
• help set up projects that are a working partnership between your individual class and EcoWater Solutions
• assist you in developing your own classroom activities around water issues.

Get started by checking out the information below which introduces the stormwater network in Waitakere City. You'll also find resource material ready to download and use.

What is Stormwater?
 

Stormwater is rain which has run off hard surfaces like roads, roofs and car parks. Stormwater travels through pipes and flows into streams and harbours. Stormwater results from human environments where natural vegetation has been cleared and replaced by lots of hard, waterproof (“impervious”) surfaces. These prevent rainwater from soaking into the ground and cause more water to run-off the ground. This run-off is erosive, fast moving and seriously polluted by modern lifestyles. It contributes to flooding, stream damage and water pollution.

Communities have traditionally piped away stormwater from their buildings, roads and carparks. The pipes carrying away this stormwater, discharge it into the nearest waterway (e.g. stream, beach, harbour, wetland). It is usually not treated in any way. Beneath our city streets, there is a complex network of stormwater pipes which carry stormwater downhill to the discharge points. For most people, the only visible signs are the familiar kerb drains and perhaps pipes at the local beach.

Stormwater Network in Waitakere City

Waitakere City's stormwater network consists of 590km of pipe, with another 25km added each year. This pipe network operates entirely by gravity with discharge pipes at streams and beaches. There are 16,212 manholes in the network and 720km of streams.

In recent years, a number of detention or treatment ponds have been constructed. There are currently a total of 23 wetland detention ponds in Waitakere City. These help to minimise flooding by detaining large volumes of stormwater during heavy rain and releasing it slowly. Treatment ponds also prevent rubbish and many of the pollutants in stormwater from reaching our natural waterways.

The network also includes 12 rainfall monitoring stations and two stream flow monitoring stations. These provide up to date information for engineers at EcoWater Solutions. A flood alarm is located in the Opanuku catchment where there is a danger of flooding.

Why Stormwater is a Problem

Pollution

Stormwater is polluted by such things as contamination from motor vehicles, air pollution, herbicides, garden fertilisers, rotting lawn clippings, detergent from car washing, domestic animal faeces, illegal and accidental spills/dumping into stormwater drains. Our modern lifestyle contributes to stormwater pollution, often unwittingly.

Stormwater pollution is both visible (plastic bags, bottles, street litter, dog poo etc) and invisible (lead, copper, zinc & oil washing off roadways). It is important to be aware of both. The invisible pollution usually involves long term, heavy duty toxins!

Wastewater overflow
 

Communities have also constructed a separate pipe network to carry away unwanted water and waste from their homes and workplaces. This is known as the wastewater or sewer system. Normally, the wastewater or sewer system operates independently but, during times of heavy rain, stormwater leaks into the wastewater network. This causes the wastewater network to overload and overflow. These overflows eventually find their way into the stormwater system and natural waterways. They add to the toxic mixture already in stormwater and pose a serious risk to public and environmental health.

Solving Stormwater Problems

Council does more than just pipe away stormwater for you. It is committed to managing stormwater in ways which:

• protect public health and safety
• improve natural water quality
• use ratepayers money wisely

To achieve these goals Council is tackling stormwater problems from many different angles. Here are some examples of current stormwater projects and initiatives happening in Waitakere City:

• Researching the big picture and planning for the future - read about the Comprehensive Urban Stormwater Strategy and Action Plan
• Implementing the latest environmentally-friendly stormwater controls - find out about swales, separators and porous paving
• Saving time and money with technology - check out the story on computer network modelling in Ranui
• Using the holistic approach to stormwater management - see why the Manawa Wetlands in New Lynn is unique
• Educating the next generation - meet The Toxic Avengers in Operation Stormwater

Swales, Separators and Porous Paving

Swales, separators and porous paving are all examples of techniques that not only control stormwater run-off but also benefit the environment.

Swales at Herald Island

Grass swales along residential streets in Herald Island form part of drainage improvements being carried out in the area. From the outside swales look like very shallow ditches but essentially they are an extension of the front lawn and are grassed waterways. Their water sensitive design elements mean that the stormwater can be managed without the traditional kerbs and pipes.

The swales help reduce erosion by slowing the flow of water and provide some measure of silt retention and soakage, thus improving stormwater quality before it enters a detention basin, artificial wetland or, in this case, the harbour.

In constructing a swale, the existing ground is regraded, compacted, top soiled and then grassed. The contouring is an important part of the design as is the placing of drainage coils and other filtering materials beneath the surface, which help prevent the swales becoming bogged in winter.

You can see another example of a swale, behind the Waitakere City Council's Civic Centre building where water-loving plants have also been used as part of the design.

Stormwater Separator at Henderson Creek

A stormwater continuous flow separator has been installed at Henderson Creek just behind Epping Park. This facility is essentially a large stormwater filter. Water flow is stemmed by passing through a combination of shaped concrete chambers and filter grates which can trap small particles of sand and silt as well as larger pollutants. The debris is collected by filter bags which are then regularly cleaned out.

Porous Paving at Parrs Park

Car park spaces with surfaces made of permeable paving stones have been constructed alongside the new road into Parrs Park. These paving stones help improve our ecosystem as well as provide an amenity with aesthetic value. It's the first time they have been used in New Zealand. Patented in England, a manufacturer in New Zealand is now producing the permeable paving.

Rainwater seeps through the porous surface slowly, filtering out oil and other debris, thereby reducing the amount of pollutants that end up in our waterways. An important part of the overall design is preparation of the ground beneath the paving stones, which may require materials such as drainage coils, scoria and filter mats.

Computer Network Modelling for Stormwater

Network modelling is a computer based tool which has significantly changed the practice of drainage engineering over the past decade. Earlier hand calculation methods were more suitable for single-scenario planning and less able to incorporate the many complexities involved in stormwater flow. These methods often resulted in conservative (and more costly) design solutions.

Computer network models represent physical processes with the help of mathematical formulas. In this way a natural stormwater catchment can be built up within a computer. The computerised stormwater catchment is really a simplified electronic version of the real stormwater catchment. The model contains all features of the three dimensional stormwater network within the catchment e.g. pipes, manholes, streams and ponds.

Engineers use these models to simulate various real time scenarios. For example, it is possible to apply an 'electronic' rainstorm and see what effects this storm has on the network and its environment. Also, the effect of possible changes to the stormwater network can be studied and various options trialled. Network modelling is a powerful tool for arriving at cost-effective engineering solutions.

Manawa Wetlands - the Holistic Approach to Stormwater Management

The Manawa Wetlands project in New Lynn is an example of solving stormwater problems by using a holistic or 'integrated management ' approach. This means that the social, economic and environmental factors are considered as well as the engineering issues. 'Integrated management' also means consulting a wide range of people before coming up with the final plan of action, including urban designers, traffic engineers, planners, ecologists, landscape architects, parks people and local residents. The end result for New Lynn, one of the oldest urban areas in Waitakere City, has been the transformation of an eyesore into a community asset, where people can meet and enjoy nature.

The Manawa Wetland Site - the way it used to be The Manawa Wetland site in New Lynn comprises 2.06 hectares which was originally used for clay quarrying, resulting in a large pit up to 15 metres deep. The clay pit site was never formally restored, part of it being used as a landfill in the sixties and early seventies. By the mid 1990s, water quality in the Manawa and Rewarewa streams which flow through the site had degenerated significantly. The community had regarded this unattractive area as dangerous. Covered in weeds and rubbish, there was also high levels of sediment in the waterways, and storm debris was trapped amongst the many exotic trees growing on stream edges.

The aims of the project

• Transform the Manawa Reserve from its past state of neglect, to an area of useable open space planted with native species
• Create a visually pleasant wetland area that is also a recreational amenity
• Create an improved stormwater management system
• Re-establish and enhance the wildlife habitat.

New stormwater controls

Stage One of the project involved forming a series of interconnected ponds below the outlet of a 700 metre piped section of the Rewarewa Stream. The rock walls between each of the interconnected ponds act as barriers to slow the rush of incoming stormwater. Plants also help to trap and filter debris.

Viewed from the southern (outlet) end, the series of ponds are clearly visible. When there is heavy rain, stormwater flows over the rock barrier from one pond to the other. As debris is trapped and sediments settle, water quality improves from the first pond to the last.

The role of plants in improving water quality

Planting native trees around the ponds:

• Shades the water lowering the temperature to promote better water quality for a wider range of freshwater species
• Provides a belt of vegetation around the ponds to filter any surface water which flows through it
• Removes some of the pollutants from the water through the process of 'evapotranspiration'
• Enhances the aesthetic and recreational value of the area

'The Toxic Avengers in Operation Stormwater' - Education through theatre

In-your-face, action-packed theatre is one way to get environmental messages across to the public. The Toxic Avengers in Operation Stormwater is a 15 minute show about urban stormwater, designed to appeal to all age groups, especially young people. It has been especially created by Theatre Frontier as a partnership project between Auckland Regional Council and the ASB Arts Access Programme at The Edge. EcoWater Solutions has supported their first two seasons of performances in Waitakere City shopping malls and schools.

"The Toxic Avengers in Operation Stormwater" is directed by Lynn Cardy and features Susan Haldane as Sabine, Judith Bishop as Tina, and Katie Parker as Lulu. The show aims to provoke the audience into looking at the 'invisible' stormwater problem and into thinking about how they personally can make a difference.

The story

After receiving an emergency call from Dwayne the Stormwater Drain, the intrepid Toxic Avengers descend into the stormwater drains to investigate. According to Dwayne, there are serious water quality problems in the Auckland region, in fact many popular beaches are regularly off limits after heavy rain and our natural waterways are becoming as polluted as those around large overseas cities.

Once inside the labyrinth of stormwater pipes, the Toxic Avengers discover that a mixture of visible and invisible pollutants are washed into the stormwater system whenever it rains. Stormwater is discharged into streams, harbours and beaches, so there are serious consequences for our recreational waterways.

Summary Of Stormwater Facts And Figures

Council:

• is developing a comprehensive asset management system to keep track of all parts of its network system. This will enable EcoWater Solutions to become more efficient in delivering and managing its services
• seeks innovative solutions to problems of water quality which result from urbanisation e.g. porous paving, swales, litter traps, cesspit bags and stormwater treatment ponds such as the Manawa wetlands in Margan Ave, New Lynn
• processes over 500 applications for subdivision drainage consent, issues over 150 engineering approvals and carries out over 150 line tests and inspections each year
• processes over 1000 applications for drainage approval on building consents each year
• receives over 2000 calls each month through the WCC call centre
• answers an estimated 13,000 fault maintenance requests each year
• gets involved in community events and projects
• provides water education resource material for schools throughout Waitakere City
• provides a public information service through brochures, handouts, newspapers and advertising.

Stormwater Educational Resources

Staff at EcoWater Solutions assist Waitakere City schools with a variety of educational projects relating to stormwater, wastewater and water supply.  This includes topic planning, resource selection and providing a visiting speaker service for classes. We encourage partnership arrangements with schools and involve local students in many successful projects of this type.

The following materials align with a number of curriculum areas and will suit a range of different ages. For additional material or specific requirements, please contact us.

Note:

All care has been taken to ensure that the information contained in these leaflets is accurate and current. If you require further information, please contact us.

Note: You will need to have Adobe Acrobat Reader installed on your computer in order to view and print these documents.  For help opening PDF files or tips on copying information see Helpful Tips.

For more information about stormwater, please contact us.