1 SEWERAGE SYSTEMS Visual inspection of sewers Michel FAVIER Technical Sales Department January 2003

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

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.

4 Visual inspection Infiltration (from the outside inwards)

5 Visual inspection Infiltration

6 Visual inspection Infiltration

7 Visual inspection Infiltration

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.

9 Visual inspection Ingrees of sand

10 Visual inspection Ingress of sand

11 Visual inspection Ingress of sand

12 Visual inspection Ingress of sand

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.

14 Visual inspection Longitudinal displacement 15mm concrete, socket & spigot Ø300

15 Visual inspection Longitudinal displacement 35mm PVC Ø500

16 Visual inspection Longitudinal displacement 40mm concrete, socket & spigot Ø400

17 Visual inspection Longitudinal displacement PVC Ø500

18 Visual inspection Longitudinal displacement PVC Ø500

19 Visual inspection Longitudinal displacement 30mm concrete, socket & spigot Ø300

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.

21 Visual inspection Radial displacement

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.

23 Visual inspection Angular displacement 1 horizontal - 2 vertical 12

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.

25 Visual inspection Visible rubber ring

26 Visual inspection Intruding rubber ring

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.

28 Visual inspection Intruding sealing material

29 Visual inspection Intruding sealing material

30 Visual inspection Intruding sealing material

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.

32 Visual inspection Surface damage

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.

34 Visual inspection Attack

35 Visual inspection Attack

36 Visual inspection Attack Reinforcement visible

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

38 Visual inspection Cracks

39 Visual inspection Cracks

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.

41 Visual inspection Deformation

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.

43 Visual inspection Intruding connection

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.

45 Visual inspection Ingres of roots

46 Visual inspection Ingress of roots

47 Visual inspection FOULING Fouling means the collection of organisms which are become attached to the pipe wall or hang it in strings threads.

48 Visual inspection Fouling

49 Visual inspection Fouling

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.

51 Visual inspection Scale

52 Visual inspection scale

53 Visual inspection ACCUMULATION OF SAND AND DEBRIS Accumulation of sand and debris refers to accumulated material having a loose struture.

54 Visual inspection Accumulation of sand and debris

55 Visual inspection Accumulation of sand and debris

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

57 Visual inspection Obstacles

58 Visual inspection Obstacles

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).

60 Visual inspection Water depth

61 Visual inspection Water depth

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

63 Visual inspection END