Education - Wastewater
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
- assist you in developing your own classroom activities around water
issues.
Get started by checking out the information below which introduces the
wastewater supply network in Waitakere City. You'll also find resource material ready to
download and use.
 What is Wastewater?
When we use water inside our
homes or workplaces, it goes down the drain into the wastewater (or sewer)
pipes.
Wastewater is nearly all water (99%), but it also contains human
body wastes, toilet paper, soap, detergent, fat, food scraps, cleaning
chemicals and everything else we pour or flush down our house drains.
Wastewater contains chemicals and micro-organisms (germs) which can make
people ill and damage the environment.
- Wastewater pipes are buried underneath the ground.
- Wastewater pipes remove wastewater from our homes and workplaces.
- Stormwater pipes remove rainwater from roofs, roads and other hard surfaces.
- Water supply pipes deliver water to homes and workplaces.
Wastewater Network in Waitakere City
Underneath your house (or workplace) is a wastewater pipe. All the wastewater
from inside the house flows into this pipe. The property owner is responsible
for maintaining this pipe sometimes called the 'sewer lateral'.
Your house's wastewater pipe goes underground away from the house until it
joins onto a much larger wastewater pipe owned and maintained by Council. This
larger pipe takes away wastewater from all the houses in your neighbourhood.
(Houses in remote areas treat their own wastewater on site with a septic tank or
similar system.)
Council's pipes flow into the regional wastewater network operated by
Watercare Services Ltd. Watercare's main pipe, which removes wastewater from
Waitakere City, is called the Western Interceptor Sewer. This carries wastewater
to Watercare's treatment plant at Mangere.
Why Wastewater is a Problem
Inflow and Infiltration
The words 'Inflow' and 'Infiltration' refer to rainwater which has flowed
into the wastewater network. Here in the Auckland region, around 40% of the
annual wastewater flow to the Mangere treatment plant is the result of inflow
and infiltration. This increases costs for transport and treatment of
wastewater, reduces network capacity, and leads to wet weather sewer overflows.
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Infiltration is rainwater which soaks through the ground and leaks
into wastewater pipes through cracks and breaks in the pipe. Tree roots,
failing joints and seasonal earth movement damage pipes allowing
stormwater to leak in. |
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Inflow is rainwater which flows into the wastewater network via low
lying gully traps, cracked manhole fittings and stormwater from roofs
that have been diverted into gully traps via illegal down pipe
connections. |
In one year, the inflow from one illegally connected house roof is the same
volume as the wastewater from 50 houses.
The impact of inflow and infiltration on our network is represented in the
following diagram.
| Dry weather flows - low inflow /
infiltration |
Wet weather flows - high inflow /
infiltration |
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 |
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| Off peak network load |
Peak network load |
Off peak network load |
Peak network load |
Wastewater pipes are underground and invisible. Most people do not consider
that these pipes need maintenance like the rest of their property. Infiltration
is an unseen problem and does not usually alert property owners that something
may be wrong with their wastewater pipes.
Solving Wastewater Problems
The Auckland region faces major decisions regarding the future management of
wastewater to cope with rapid population growth and an ageing infrastructure.
Council is committed to managing wastewater in ways which will:
- protect public health
- enhance environmental values
- use financial resources wisely
New Lynn Infiltration Control Programme
New Lynn is one of the oldest parts of Waitakere City with many original
sewer pipes dating back to the late 1920's.
The Council has commenced an eight year programme to address infiltration and
inflow in New Lynn. The programme involves property inspections plus renewal and
replacement of approximately 90% of the wastewater network.
Where possible, trenchless methods are used to rehabilitate wastewater pipes
that are contributing to infiltration.
A 'bursting head' device is positioned into an existing drain. This expands
and bursts the pipe walls outwards. A new flexible pipeline is then drawn
through the enlarged existing pipeline.
In the first year of this programme, major success have been achieved in the
targeted mini catchments:
- the volume of infiltration and inflow has reduced by 47.3%
- peak wet weather flows have decreased by 26.2% compared to a target of
25% reduction
- average dry weather flows have increased by 44.7%. This volume was
previously escaping to the environment through defects in the wastewater
network, known as 'exfiltration'.
This has involved the following works:
- 1540m of the Council's wastewater network replaced
- 100 connections repaired or replaced
- 20 manholes replaced
- 9 manholes repaired
Summary of Wastewater Facts and Figures
Council
- removes 13 million cubic metres of wastewater each year from homes and
workplaces within the city
- maintains (repairs, unblocks and monitors) a wastewater network
consisting of 934 kms of pipe, 46 pumping stations, 414 pipe bridges, 20,502
manholes
- provides expert advice and guidance on regulatory matters concerning
drainage
- manages public consultation programmes with regards to future options
for the management of the three waters
- carries out water quality testing
- manages and gives advice to the septic tank maintenance programme
maintains a team of customer field officers to handle all customer enquiries
and general water investigations
- manages contracts with a range of independent contractors for the
ongoing maintenance and development of our networks
- is developing a comprehensive asset management system to keep track of
all parts of its network system. This will enable EcoWater to become more
efficient in delivering and managing its services
- 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 Waitakere City Council
call centre
- answers an estimated 13,000 fault maintenance requests each year
- gets involved in community events and projects
- provides wastewater educational resource material for schools throughout
the city
- provides a public information service through brochures, handouts,
newspapers and advertising
Wastewater Educational Resources
EcoWater Solutions assists Waitakere City schools with a variety of
educational projects relating to stormwater, wastewater and water supply.
Our staff help with topic planning, resource selection and provide 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.
Module 6 - Wastewater
Ways you can help
The following are educational flyers about wastewater overflow and what we
can do to avoid problems with wastewater.
The document has been translated
into seven different languages.
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