sewer appurtenance

INTRODUCTION
• Sewer appurtenances are the various accessories on the sewage system in
order to make the process of construction easy and to have efficient working
and maintenance.
• If sewer system is not properly maintained silt, ashes, grit, fats, oil etc. will
chock the sewer lines, therefore, for proper operation and maintenance of
sewer system various devices are required.
Appurtenances are as follows:
• MANHOLE
• CATCH BASIN
• CLEANOUTS
• OIL AND GREASE TRAP
• INLETS
• LAMPHOLES
• SEWER VENTILATORS
• STORM WATER RAGULATORS
• INVERTED SIPHONS

MANHOLE
Drop
Manhole
Flushing
Manhole
Straight-
through
Manhole
Junction
Manhole
STORM WATER
REGULATOR
Overflow
Weir
Siphon
Spillway
Leaping
Weir

MANHOLES
• A manhole is an opening constructed on the alignment of sewer to facilitate a person
access to the sewer for the purpose of inspection, testing, cleaning and removal of
obstruction from the sewer line.
• The main objective of construction of manhole is firstly they permit inspection,
cleaning, maintenance of sewer line and the obstructions in the sewage is collected
in manholes.

• Secondly it
allows the
joining of
sewers or
changing the
direction or
alignment.
• If the manhole
covers are
perforated,
they will allow
the escape of
undesirable
gases and thus
ventilation will
also be
achieved.
MANHOLE
are classified as :
SHALLOW MANHOLE
NORMAL MANHOLE
DEEP MANHOLE

SHALLOW MANHOLE
• It is constructed at the start of branch sewer or at places, which are not subjected to heavy
traffic such as domestic areas.
• These manholes are provided with light cover at its top and are called INSPECTION
CHAIMBER.
• These are 0.70m to 0.90m deep.
NORMAL MANHOLE
• It is about 1.5m deep .
• It is constructed either square or rectangular in cross-section.
• Such manholes are provided with heavy cover at its top.
DEEP MANHOLE
• The depth is more than 1.5m.
• Steps are provided in such manholes to enable workers to go up to its bottom.
• These manholes are also provided with heavy cover at its top.

Components of Manhole
A manhole is
considered to be
made of three
parts:
 Manhole cover
resting on a
heavy frame
 Access shaft
 Working
chamber
MANHOLE-COVER
The manhole is provided with
cast iron cover and a cast iron
frame at its top. Size of
rectangular cover is about
0.6mX0.45m and diameter of
circular circular cover is 0.5m-
0.6m.
ACCESS SHAFT
The upper portion of a deep
manhole is called access shaft.
WORKING CHAMBER
The lower portion of a
manhole is known as working
chamber which provides
working space to carry out
cleaning and inspection of
sewer line.

STRAIGHT THROUGH
MANHOLE
• It is the simplest type
of manhole which is
constructed on a
straight run of sewer
with no side junction.
JUNCTION
MANHOLE
• This manhole is built at
every junction of two or
more sewers.
• The soffit of the smaller
sewer at a junction
should be not lower
than that of the larger
sewer.
DROP MANHOLE
• A manhole in
which vertical pipe
is used is called
drop manhole.
• When a high level
branch sewer is
connected to low
level main sewer
so a vertical pipe is
used.
• It is used when
branch sewer
enters a manhole
by more than 0.5m
to 0.60m above
the main sewer.
MANHOLE TYPES

FLUSHING MANHOLE
• It is a tank holding a supply of water or
sewage for periodically flushing out a sewer.
• Where it is not possible to obtain self cleaning
velocities due to flatness of gradient specially
at the top ends of branch sewers which
receive very little flow. This can be done by
making grooves at intervals of 45-50m in main
drains in which wooden planks are inserted
and water allowed to head up and which will
rush on with great velocity when planks are
removed.

CATCH BASIN
• A catch basin or a catch pit are small masonry chambers which
are constructed below the street inlets to allow flow of water
free from silt, grit etc. into sewer lines.
• The catch basins collect solids from storm water. These solids
are to be removed frequently otherwise they will block the
passage.
• The sewer cleanout
fitting provides a point
of insertion
perpendicular to the
direction of flow in the
main pipe, but it is
angled in such a way
that anything you
insert into the fitting
(such as a drain snake)
cannot go against the
flow of waste water.
• A cleanout is generally
provided at the upper
ends of lateral sewers
in place of manholes.
CLEANOUT
S

OIL AND GREASE
TRAP
• A grease trap is a plumbing device (a
type of trap) designed to intercept
most greases and solids before they
enter a wastewater disposal system.
Common wastewater contains small
amounts of oils which enter into
septic tanks and treatment facilities
to form a floating scum layer. This
scum layer is very slowly digested
and broken down by microorganisms
in the anaerobic digestion process.
• Large amounts of oil from food
preparation in restaurants can
overwhelm a septic tank or
treatment facility, causing release of
untreated sewage into the
environment. High-viscosity fats and
cooking grease solidify when cooled,
and can combine with other disposed
solids to block drain pipes.

LAMP HOLES
• A lamp hole is a small opening or hole
constructed in a sewer for the purpose
of lowering a lamp inside.
• The lamp light is then viewed from the
upstream as well as downstream
manholes.
• The obstructed light confirms the
obstruction in the sewer.
• If the construction of manhole is
difficult, lamp hole may be constructed
at its place.

STORM WATER RAGULATOR
• The main object of providing a storm water regulator is to divert the excess storm water to natural
stream or river.
• The excess sewage will be mainly composed of storm water and it will therefore be not foul in nature.
There are three types of storm water regulators:
1. Leaping weir
2. Overflow weir
3. Siphon spillway
LEAPING WEIR
The term leaping weir is used
to indicate the gap or opening
in the invert of a combined
sewer. It has no has no
moving parts. When the
discharge is small, the sewage
falls directly into intercepting
sewer through the opening.
But when discharge exceeds a
certain limit, the excess
sewage laps jumps across the
weir and it is carried to natural
stream or river.

In this type of arrangement, the
excess sewage is allowed to
overflow in the channel made in
the manhole. When the quantity
of sewage exceeds the capacity
of combined sewer, it overflows
and falls into the channels and it
is conveyed to storm water
sewer. In order to prevent the
escape of floating matter from
combined sewer channel, the
adjustable plates are sometimes
provided.
OVERFLOW WEIR

• It works on the principle of siphon
action.
• It is automatic in functioning and this
is the most effective in all other
methods. This arrangement has no
moving parts and thus low
maintenance.
• However it is likely to be clogged due
to narrow passages.
SIPHON SPILLWAY
INVERTED SIPHONS
• An inverted siphon is a sewer section which is
constructed lower than the adjacent sewer
section and which runs full under gravity with
pressure greater than the atmosphere.
• inverted siphons are used to carry sewage or
stormwater under streams, highway cuts, or
other depressions in the ground. In an
inverted siphon the liquid completely fills the
pipe and flows under pressure, as opposed to
the open-channel gravity flow that occurs in
most sanitary or storm sewers.

SEWARE VENTILATORS
• Various gases are produced in the
sewer due to decomposition of
organic materials of sewage.
These gases are foul in nature ,
cause harm to human health. The
gases produced are highly
explosive and may cause
explosion.
• Due to these problems ventilation
is provided at every 80-100M
which will provide fresh air to the
workers working in the manhole.
• It may be of RCC or cast iron 15 to
23cm in diameter with a cowl
provided at the top.

Reference
• Wikipedia
• Google images

sewer appurtenance

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sewer appurtenance