Glossary of
Stormwater Terms
March 2016
Glossary of Stormwater Terms
Aerator Fountain Is used in ponds to circulate water.
Can help to reduce the build-up of silt and increase oxygen to
avoid or reduce water quality issues
Aquifer Describes underground layers of saturated permeable material
(for example, gravel or fractured rock) that can both hold and let
water move through
As Built Plan Plans showing details of fittings and connections on a site. May
also show new public assets and their connection to existing
networks
Baffle Is a device used to deflect or regulate water flow. May also be
used to enable sediment separation. See energy dissipater
Bandalong Is a brand name for a floating debris screen
Bear Trap Large inlet grille that allows access to the network during heavy
rain events
Bubble up catchpit Describes a catchpit which does not have an outlet pipe.
It allows the water to bubble up and flow overland to the nearest
receiving point e.g. river, beach, or catchpit that is connected to
the reticulation network.
These are not commonly used.
Bund Barrier, dam or mound used to contain or deflect substances,
particularly sediment.
Often used to prevent a spill from entering the stormwater
system
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Catchpit/Cesspit Stormwater device composed of a grate, small chamber and
sediment trap.
May be private or public and are usually associated with
drainage of roading or driveways. Varieties include supa pits,
mega pits or splay pits.
A cesspit is technically a wastewater device, although the terms
are often used interchangeably
Catchment Area Describes an area of land where the stormwater runoff would
flow to a discharge point at a watercourse or the sea.
Runoff usually defined by land topography levels and measured
in hectares
Catchment Plan for dealing with runoff generated in a catchment to meet
Management Plan specific water quality and quantity objectives
(CMP)
CCTV Closed circuit television camera inserted into a pipe to capture
a recording of the inside for real-time or later analysis.
The camera may be mounted on a remote controlled vehicle or
flexible tubing.
Chamber The area within manholes and catchpits where stormwater goes
before going out through the pipes
Channels, Streams A channel is a built feature which carries surface water and is
and Watercourses open to the air.
Streams are natural features.
A watercourse is a generic terms that covers both channels and
streams.
Lined (with concrete) channels make the water flow away more
quickly
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Coastal Beach or at-sea exit point of stormwater from the piped network
Discharge/Beach
Outfall
Culvert Pipe or concrete box structure usually installed within a
watercourse.
It may be used to allow water to pass underneath a road,
railway, or embankment, or used on driveways where there is
no kerb and channelling
Dam Built to store stormwater to control flooding, water for drinking
supply, power generation, or irrigation.
Detention Pond Primarily for holding stormwater runoff to prevent downstream
flooding and erosion by releasing water at a slower rate than at
which it enters.
Similar to a wetland but generally much larger because of the
need to contain greater water volumes
Debris Screen Used in watercourses to ensure litter does not enter the
stormwater network and eventually, harbours.
May also be installed in manmade ponds and treatment
devices. Also known as trash racks or litter traps.
Downpipe Pipes from guttering to the ground which carries rainwater to
the reticulated stormwater or combined system, private ground
soakage device or rain tank
Embankment Mound or wall of soil or stone around a water asset to create
extra storage capacity than the natural ground level would allow
Energy Dissipater Rocks or concrete pads constructed at outlets to slow or
regulate water flow and prevent erosion.
Baffles are a type of energy dissipater
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Erosion Abrasion, detachment and removal of soil by rain, flowing
water, wind, frost, temperature change or other natural or
human-made causes.
Erosion causes soil to mix with stormwater to create sediment
which may be harmful to the environment
Fish Ladder/Fish Device used to enable fish species to climb barriers in built
Passage stormwater networks
Floodgate See tide gate
Flood Plain Area that a watercourse covers when it floods the surrounding
land
Flood Sensitive Area Area bordering a flood plain that has potential to be inundated
in a 100 year flood
Flume Bag Flexible tube with a flared end which connects to the end of a
stormwater pipe.
Often used for cliff-top discharges where its flexibility allows
better positioning and flared end minimises erosion
Gabion Basket Flexible or rigid wire cage filled with rocks which acts as a
retaining wall.
May be used as a bund to separate sections in ponds
Grate/Grille Steel slotted cover primarily used as a safety device.
Also allows runoff to enter the stormwater system, but prevents
the entry of blockage-causing debris
Grease Trap/Grease Device to prevent grease and solids entering the wastewater
Interceptor network and allows the grease to be collected and disposed of
safely.
Grease and fat build-up is a major cause of pipe blockages
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Ground Water Water that has seeped from the surface to subsoil and rocks.
Groundwater can surface again, particularly at the base of
slopes, or through retaining walls. Responsibility for managing
ground water lies with the property owner
Gully Trap Access point to private drainage (wastewater) for maintenance
or cleaning.
Located usually at side of a building and often has a metal or
plastic grille on top to prevent debris entering the private line
Gutter/Spouting Narrow trough fixed under the eaves of a house for carrying
rain water to downpipes
Hinged Manhole A cover connected to a manhole frame using a hinge. If the
Cover manhole surcharges the lid will drop back into place rather than
dislodging.
A dislodged manhole lid is an urgent health and safety issue.
See surcharging manhole
May also be known as a Korum lid – Korum is a brand who
produce them
Hydro Blaster/Hydro High pressure water-blaster used to remove tree roots from
Jet inside pipes
Impermeable or Hard surface area which prevents or retards the entry of water
Impervious Surfaces into the soil.
Examples include roofs, car parks and concreted areas
Infiltration Passage of water through the soil to become ground water.
Also used to describe the process of ground water entering
storm or wastewater pipes
Inlet Entry point to a piped network.
This is usually from a watercourse, pond, or channel
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Inlet Grille Steel bars installed at an inlet to prevent the entry of large
debris which may cause a blockage.
It also prevents the public from entering the network
Invert Describes the bottom of a pipe or channel.
GIS may show invert level or depth from the manhole lid to
invert, allowing the depth below ground level of the pipe to be
determined
Kerb Outlet Discharge point into the roadway of stormwater which is
collected from a property in a pipe, then passes under the
footpath/driveway.
Lined Channel Watercourses lined with concrete or other material to increase
the rate at which water flows away and minimise erosion.
Manhole Chamber that provides entry to the piped network.
Access is via a cover which may be lockable to prevent
unauthorised entry. See hinged manhole cover and surcharging
manhole
Mega Pit See catchpit
100 Year Flood Plain Land which may be innudated with water if a 100-year rain
event occurs.
A 100-year event is of a size that would typically occur only
once in 1-100 years
Orifice Small outlet from a detention tank/pond that controls
stormwater outflow
Outlet/Outfall End of a stormwater pipe or network where water leaves the
built stormwater system and enters the natural environment, at
a watercourse, lake or beach, pond etc
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Overland Flow Path Route taken by runoff not captured in the reticulated or natural
stormwater system.
If there is too much rainfall for the stormwater system to
contain, the water will begin to flow across the ground and
concentrate in gullies.
Permeable/Pervious Natural ground surfaces including trees, shrubs, grass and soil
which allow water to pass through and soak into the ground,
reducing the volume of runoff flowing over the ground.
Pump Station Installation to pump stormwater from a lower to a higher area.
May be inside a building or fenced
Rain Tank An above or below-ground tank used to store water collected
from the guttering of a building.
Not typically used for drinking water unless in areas of non-
reticulated water supply such as rural properties.
Rain Garden Planted area of lower ground which absorbs runoff from
impermeable areas.
Rainwater A rain tank which is used to temporarily store rainwater and
detention/retention release it at a slower rate through a specially designed orifice.
tank
Recharge Pit See soakage pit
Retaining Wall Reinforced wall, usually constructed from timber, concrete or
masonry, designed to prevent higher ground from collapsing
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Reticulation Piped network which carries stormwater.
The term is also used for water supply and wastewater
Riprap Also known as scour.
Rock or other material used to armour shorelines, streambeds,
bridge abutments, pilings and other shoreline structures against
scour and water or ice erosion.
Lid
Riser Underground, vertical section of a manhole which rises up from
the pipes at the base to ground level
Steps
Riser
Pipes
Roof Garden Any garden on a roof; roof gardens may delay stormwater peak
flow, and reduce the volume and rate of runoff.
The runoff may be stored for later use in the garden
Root Cut Water blasting or mechanical sawing to remove tree roots
which penetrate pipes through cracks, joints or connections,
and cause blockages
Runoff Water flows which result from rain water which is not absorbed
by permeable surfaces or that which falls on impermeable
surfaces
Safety Grille Metal grille bolted just under a manhole cover which prevents
access if the cover becomes dislodged.
Grille may be permanent or temporary
Sand Filter An above or below ground tank containing a bed of sand to filter
stormwater runoff and remove sediments and contaminants
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Scruffy Dome Steel grille, usually domed, placed over the inlet of a manhole
to allow stormwater runoff to enter the piped network but
preventing larger debris from doing so
Sediment Tiny fragments of organic or inorganic matter suspended in
water. Sediment is a pollutant caused by erosion and earth
works
Sediment Trap A device which can trap coarse sediment. Also known as a silt
trap
Seepage Usually a flow of subsoil water, sometimes containing silt or iron
bacteria, appearing at ground level, in shallow excavations or
from behind retaining walls.
If orange coloured it’s frequently confused with wastewater
leaks
Sewer Another name for a wastewater pipe
Slip In relation to stormwater may be a cliff face slip associated with
a stormwater asset
Soakage Belowground pit to collect runoff and allow it to soak naturally
Pit/Trench/Soak into the soil.
Holes
The covers for these are same as a manhole cover.
Spillway Path designed to be taken by runoff when the capacity of a
pond or dam is exceeded by a rain event or when the outlet is
blocked
Splay Catchpit Usually has a higher entry capacity and lower likelihood of
blockage than a standard catchpit
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Stop Bank An earth bund or embankment to prevent water flowing in a
particular direction. Usually used to prevent frequent flooding,
but will not prevent all flooding
Stormwater Stormwater is rain that has reached the ground
Stream See watercourse
Subsoil drain A subsoil drain is laid underground and allows for the collection
and passage of subsoil water to a stormwater drain.
This can be used to increase the stability of the land especially
around building footings, reduce surface water for example, under
a lawn and reduce subsoil water pressure such as in a building
basement.
Sucker Truck Vacuum truck that sucks up debris and silt from pipes,
manholes, catch pits etc
Sump The bottom of a catchpit below the outlet where sediments
settle. Often the whole catchpit is referred to as a sump
Surcharging Manhole When stormwater flows out of a manhole at ground level.
Surcharging may be caused by blockages in downstream pipes
causing water to back-up, or by excess water in the pipes
during a heavy rain event.
The force of the water may dislodge the manhole cover or lift it
off completely.
A dislodged manhole lid is an urgent health and safety issue
Swale Area of land that has been shaped to allow a watercourse to
form during heavy rain. They often indicate an overland flow
path.
See unlined channel
Tide Gates Gate or valve device at the outlet of a pipe or channel to
prevent water backflows from a watercourse or the sea from
tidal effects
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Tomo Area of underground erosion (not always visible) caused by the
scouring action of water, often around a fixed object such as a
pipe or manhole.
May also be caused by soil entering a crack in a pipe and
slowly forming a void
Treatment Device Generic term to cover a wide range of devices to remove
contaminants from runoff. Examples of treatment devices
include sand filters, detention ponds, and tree pits
Collects stormwater runoff from impermeable areas. Runoff
filters through the tree roots and surrounding soil, trapping
Tree Pit Collects stormwater runoff from impermeable areas.
Runoff filters through the tree roots and surrounding soil,
trapping pollutants before entering a piped storm water system
Unlined Channel Built channel with grass banks (also may refer to a natural
section of a watercourse).
A swale is a type of unlined channel designed to manage a
larger flow
Wastewater Water which has been used by, and discharged from homes,
businesses, farms, and industries.
Water Table Top of an area of permanently saturated soil underground.
The water table level can be within a few centimetres of the
surface or metres below and may change over time.
See ground water and aquifer
Watercourse/Streams A natural depression in the land contour that collects and
directs ground water and runoff before discharge into a pond,
piped network or the sea.
Described as permanent meaning they usually contain water all
year round, or intermittent meaning that they will hold water for
a short while after a rain event and then be dry until the next
event.
Wetland Shallow pond that supports a natural ecosystem of plants and
animals that are adapted to wet conditions.
Wetlands typically provide treatment of stormwater by removing
sediment which contains contaminants such as heavy metals
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Wingwall Wall at an inlet or outlet from a pipeline or culvert designed to
prevent erosion of the surrounding soil.
Usually made of concrete.
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Glossary of Other
Utility Company
covers & lids
March 2016
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Asset Name Description Photo
This box houses the connection point
between the private property and the public
wastewater network.
Boundary Kit
(PWC) They are the same size as the water meter
box but have a red lid. They sit on the berm
outside the property boundary.
Shown in GIS as:
Written on lid: Pressure Sewer Control Valve
Do Not Bury
Stormwater device composed of a grate,
small chamber and sediment trap.
Catchpit/Cesspit
(Public) May be private or public and are usually
associated with drainage off road or
driveways.
Varieties include supa pits, mega pits or splay
pits.
A cesspit is technically a wastewater device,
although the terms are often used
interchangeably.
Shown on GIS as:
There are a number of these on private
property and is the responsibility of the
property owner. They are not usually shown
Catchpit on GIS.
(Private)
If there is no public stormwater shown in the
vicinity on GIS then the maintenance of these
falls to the property owner. They are usually
smaller than what is seen out in the road
areas.
These are normally in front of garages to
catch any surface run off and are the
Channel responsibility of the property owner to
grate/slot drain maintain if within the private property.
They are also found in pavements and are
then the responsibility of Auckland Transport
Refer to Vehicle Crossing
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Downpipe Pipes from roof gutter of house to carry
rainwater to reticulated stormwater system
Gas is yellow, power is orange (sometimes
they use grey as it goes up the power pole),
telephone is green
Gas, Power and
Telephone
conduits
Utility Company: Vector for power and gas
Utility Company: Spark for telephone
A trough fixed under the eaves of a house for
Gutter carrying rain water to downpipes and into the
(spouting) reticulated stormwater system
Access point on private drainage usually at
side of dwelling or other structure.
Gully Trap
Maintenance point for cleaning. Usually has a
rectangular plastic grille on top to prevent
debris entering the private line.
Hydrant paint The yellow triangle in the road indicates the
mark hydrant – this is for easy location when the
Fire Services need to locate in case of
emergency
Blue Raised The blue raised marker also indicates hydrant
marker
Power company Vector or other electricity provider
utility box
On site wastewater tank this unit grinds the
Pressure waste before pumping to the public network –
Wastewater Unit these are a recent addition to the wastewater
(PWC) network.
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Stormwater device composed of chamber.
Splay Usually associated with drainage of roads.
Catchpit/Cesspit
Shown on GIS as:
Steel lids on the berm/grass verge or
Telecom sometimes on the footpath itself. This is for
chamber access to the underground telephone cables
For access to the fibre-optic cables, usually
Telecom cover located on the footpath. Metal lid, clearly
marked “Telecom”
Telecom Indicates underground telephone cables
Indicator
Utility boxes Black is “live cables” and grey are old
fashioned telephone cable boxes
For ease of location the blue marking
indicates the concrete markers (see next
photo) which in turn is located very close to
Valve marker the valve box
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Blue painted concrete marker posts marked
PV or SV or just V. These relate to water
Valve – peet supply
valve and sluice
valve Shown on GIS as:
Water meter boxes can have blue or black
plastic lids, the box itself is also made of
plastic.
In the past, these lids were steel. Steel lids
Water meter are still used in high traffic areas where
vehicles could be damaging the plastic boxes.
These are normally located on the berm,
close to the property boundary.
If the meter is ticking over, there is water
usage (leakage) on the private side. If there
is no movement on the meter, but there is a
wet area on the berm or water is visibly
running (and it is not raining currently or for
the last couple of days), there might be a leak
on the public side of the meter and Watercare
needs to rectify.
The round water meter cover can be found in
the western areas of Auckland, these are only
about 30cm across – and not to be confused
with a manhole which is approx 55cm across
Even though this meter box is on the berm,
the meter inside the box is the private/public
divider.
The water on the public side will not register
on the meter, where if the private side has a
leak or is using water, the meter will be
Water supply - turning over.
blue
Home owners can do an overnight test on the
meter to establish if they have a leak by, last
thing at night taking a meter reading, shutting
the valve and then not to use any water
overnight.
First thing the next morning to go back and
take another reading. When they open the
valve, and water rushes through, it clearly
indicates that there is a leak on the private
side.
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A vehicle crossing is the area of driveway
Vehicle between the council road and the private
Crossing property boundary. The area of driveway
on private property is not part of the vehicle
crossing.
The vehicle crossing will usually replace a
portion of the public footpath and may have a
grate covering drainage. Vehicle crossings
with grates are referred to as hi-volume
vehicle crossings.
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