1 SEWERAGE SYSTEMS Visual inspection of sewers Michel FAVIER
Technical Sales Department January 2003 Slide 2 2 Visual inspection
The different condition aspects Water tightness: - infiltration -
ingress of sand - longitudinal displacement - radial displacement -
angular displacement - intruding rubber gasket ring - intruding
sealing material Slide 3 3 Visual inspection INFILTRATION
Infiltration means the ingress of ground water through joints,
cracks or inlets or through the pipe wall (if the sewer is wholly
or partly in the ground water). - ground water drips into the
sewer. - ground water flows into the sewer. - ground water gushes
or flows into the sewer inlarge quantities. Slide 4 4 Visual
inspection Infiltration (from the outside inwards) Slide 5 5 Visual
inspection Infiltration Slide 6 6 Visual inspection Infiltration
Slide 7 7 Visual inspection Infiltration Slide 8 8 Visual
inspection INGRESS of SAND Ingress of sand means the intrusion of
sans through pipe connection or cracks. The degree to which sand
intrudes depends on quantity of sand entering the sewer per unit of
time. This quantity per unit of time is often difficult to measure
because: - on visual inspection, only a momentary picture is
obtained. - the water flow removes all or part the intruded sand.
Slide 9 9 Visual inspection Ingrees of sand Slide 10 10 Visual
inspection Ingress of sand Slide 11 11 Visual inspection Ingress of
sand Slide 12 12 Visual inspection Ingress of sand Slide 13 13
Visual inspection LONGITUDINAL DISPLACEMENT Longitudinal
displacement means a uniform displacement of two pipes from one
another along the axis of pipes. Sometimes the connection between
two pipes is then interrupted. Slide 14 14 Visual inspection
Longitudinal displacement 15mm concrete, socket & spigot 300
Slide 15 15 Visual inspection Longitudinal displacement 35mm PVC
500 Slide 16 16 Visual inspection Longitudinal displacement 40mm
concrete, socket & spigot 400 Slide 17 17 Visual inspection
Longitudinal displacement PVC 500 Slide 18 18 Visual inspection
Longitudinal displacement PVC 500 Slide 19 19 Visual inspection
Longitudinal displacement 30mm concrete, socket & spigot 300
Slide 20 20 Visual inspection RADIAL DISPLACEMENT Radial
displacement is the displacement of two pipes in relation to each
other perpendicular to the axis of the pipes. Sometimes radial
displacement means that the socket or spigot is broken. Slide 21 21
Visual inspection Radial displacement Slide 22 22 Visual inspection
ANGULAR DISPLACEMENT Angular displacement refers to a divergence in
line of pipes from one another along the axis of the adjoining
pipe. This divergence may occur both horizontally and vertically.
The permissible angular deflection depends of the dimensions of
pipes with a socket-and-spigot. Slide 23 23 Visual inspection
Angular displacement 1 horizontal - 2 vertical 12 Slide 24 24
Visual inspection INTRUDING RUBBER RING An intruding rubber ring
means a visible, intact rubber ring or broken ring partly hanging
into the cross section of the sewer. Slide 25 25 Visual inspection
Visible rubber ring Slide 26 26 Visual inspection Intruding rubber
ring Slide 27 27 Visual inspection INTRUDING SEALING MATERIAL
Intruding sealing material means sealing material (sealant or
bituminus sealing strip) sagging out or squeezed from the joint in
the cross-section of the sewer. Slide 28 28 Visual inspection
Intruding sealing material Slide 29 29 Visual inspection Intruding
sealing material Slide 30 30 Visual inspection Intruding sealing
material Slide 31 31 Visual inspection SURFACE DAMAGE Surface
damage means damage to the surface caused during manufacture,
transport or laying of the sewer or resulting from works on or
around the sewer. Slide 32 32 Visual inspection Surface damage
Slide 33 33 Visual inspection ATTACK Attack means a reduction of
pipe wall over of use as a result of chemical, bio-chemical or
mechanical processes. Concrete: - no grit visible - grit visible -
reinforcement possibly visible and rusted PVC: - no or degradations
noted NB. Resistance of collapse cannot be observed visually. Slide
34 34 Visual inspection Attack Slide 35 35 Visual inspection Attack
Slide 36 36 Visual inspection Attack Reinforcement visible Slide 37
37 Visual inspection CRACKS Cracks means a complex of cracks,
fractures and / or broken parts. Type of cracks: - hair cracks -
non-open cracks - open cracks - parts of the pipe displaced or
collapsed Slide 38 38 Visual inspection Cracks Slide 39 39 Visual
inspection Cracks Slide 40 40 Visual inspection DEFORMATION
Deformation means an alteration in the cross- section / diameter in
relation to the original cross-section / diameter. The degree of
deformation is expressed as a percentage of the original
cross-section / diameter. Where deformation varies, the maximum
deformation is taken. Slide 41 41 Visual inspection Deformation
Slide 42 42 Visual inspection INTRUDING CONNECTION An intruding
connection means a lateral of service connection pipe from any
building or gully pit, projecting into the sewer. Slide 43 43
Visual inspection Intruding connection Slide 44 44 Visual
inspection INGRESS OF ROOTS Ingress of roots means roots from trees
or plants growing into the sewer through joints, cracks or
connections fom buildings and gullies. NB. Roots penetration occurs
only in sewers laying partly or above the ground water level. Slide
45 45 Visual inspection Ingres of roots Slide 46 46 Visual
inspection Ingress of roots Slide 47 47 Visual inspection FOULING
Fouling means the collection of organisms which are become attached
to the pipe wall or hang it in strings threads. Slide 48 48 Visual
inspection Fouling Slide 49 49 Visual inspection Fouling Slide 50
50 Visual inspection SCALE Scale means the depositing of silt,
grease and lime cake on the pipe wall. This condition aspect also
includes encrustation and deposits of soil material (other than
sand) around a pipe connection or cracks. Slide 51 51 Visual
inspection Scale Slide 52 52 Visual inspection scale Slide 53 53
Visual inspection ACCUMULATION OF SAND AND DEBRIS Accumulation of
sand and debris refers to accumulated material having a loose
struture. Slide 54 54 Visual inspection Accumulation of sand and
debris Slide 55 55 Visual inspection Accumulation of sand and
debris Slide 56 56 Visual inspection OBSTACLES Obstacles refers to
objects in the sewer without any function for the sewer system and
which are not part of ordinary sewage flow. Examples of obstacles
in the sewer are: - dislodged bricks - unremoved shuttering -
branches and wood - collapse of the sewer Slide 57 57 Visual
inspection Obstacles Slide 58 58 Visual inspection Obstacles Slide
59 59 Visual inspection WATER DEPTH Water depth means the water
level in relation to the bottom of the pipe. This water stagnates
into the sewer ( for example in a low point). Slide 60 60 Visual
inspection Water depth Slide 61 61 Visual inspection Water depth
Slide 62 62 Visual inspection ADDITIONAL REQUIREMENTS Before to
start an inspection, identification and inventorisation data must
be available. Such as: - the name of the local authority - name of
street and district - the numbers of the the manhole chambers and
the direction of wich inspection is made - inspection date - the
material of the pipes - the type and position of connection pipes
NB. It is useful to have drawings available during inspection Slide
63 63 Visual inspection END
