(Table: Other obstacles – Brick on top of the pipe bottom)

(Table: Other obstacles – Third party pipe traversing the piping)

(Table: Other obstacles – Object intrudes through a connection)

(Table: Other obstacles – Object trapped in the piping)

(Table: Other obstacles – Plastic foil got caught at an intruding connection)

In most of these cases, other types of defect are the root cause for the existence of objects in drains and sewers. Thus, bricks, masonry, or wall pieces that can be found on the pipe invert can often be traced back to a pipe break/collapse. These causal types of defect must not necessarily have occurred immediately in the area of the object, but can also have occurred against the direction of the flow or in a connection / lateral sewer.

On the other …

Possible consequences of defect that are categorised in the main code “Other Obstacles” are:

Leakages and thus, infiltrations can occur on their own or in combination with other types of
defect in the following areas:

• pipe joints

• pipe walls

• branches, connections, and laterals

(Table: Infiltration – Gushing)

(Table: Infiltration – Gushing as a consequence of missing mortar)

(Table: Infiltration – Gushing)

Infiltration is a form of secondary defect as a consequence of leakages and, in turn, represents the starting point for further possible types of damage and their consequences [Horne85] [Young84].

It always occurs when leaking gravity pipelines or structures of the local drainage service lie in groundwater either permanently or temporarily. In that case, the phenomenon is called groundwater infiltration or groundwater-induced infiltration water. Simultaneously, …

Consequences of defect caused by infiltration are:

• increased groundwater-induced infiltration water percentage, and thus a higher discharge of pollutants into the bodies of water [Dohma1989]

• increased costs for sewage transport and –cleaning as well as the increase in the sewage fee

• increased operational expenditure

• hydraulic surplus load (where applicable overload of the sewers, pumping plants and/or treatment works, increased release frequencies, …

Visible exfiltrations in the sense of EN 13508-2 occur relatively rarely in sewer systems, as these require large-scale forms of primary defects (leakages), particularly in the invert of a sewer, and a largely unimpeded water runoff into the underground. Furthermore, in order to capture this type of defect, the sewage discharge has to be maintained during the inspection period. The latter stands in direct contrast to the requirement of keeping the …

Exfiltration is a consequential defect due to leakages and, in turn, represents the starting point for other
types of secondary defect along with their consequences [Horne1985] [Young84]. In that context, the
following consequences should be considerd:

• Effects on adjacent pipelines, structures or the road surface

• Change in the bedding conditions with subsequent types of defect, pipe break/collapse, deformation, fissure formation or displaced joints

The main code "vermin" according to [EN13508-2:2011] refers to "Vermin actually
observed". On the one hand, the finding is characterised according to the animal species:

• Rat (code specification A),

• Cockroach (code specification B),

• Other species (code specification Z; further remarks supposed to be recorded)
  

and secondly depending on the localisation:

• In the pipeline (code specification A)

• In a connection (code specification B)

• In an open pipe …

(Image: Vermin (rats) in a sewer)

Possible causes for vermin in drains and sewers are leakages and other unsealed types of access that allow the animals to enter the system. Furthermore, rats can also be attracted by wrongly disposed left-over foods or deposits of fecal matter. The sewer system represents a safe retreat at a comfortable temperature that is rather avoided by natural enemies. Especially in winter, the former fact makes sewers the chosen …

Possible consequences that can occur due to the presence of vermin are, for example:

• health hazards (rats are considered to be disease carriers)

• increased pollution of the sewers

• structural damage caused by the digging- and nibbling behaviour of rats

• deposit formation (BBC)

• risk of congestion

• backwater

In order to minimize health risks, pest control programmes should be developed and executed following the national or local requirements and …

This lesson builds on the module "Application of coding systems using the example of EN 13508-2" and introduces the coding of damage (findings) for sewers and drains. In more detail, the causes and consequences of damage are explained for the damage and, in some cases, the damage mechanisms are presented as well.

Upon successful completion of this course, you will be able to:

• apply the coding system according to EN 13508-2
• classify damage
• name causes and consequences of damage

The excavation of utility trenches and tunnels and their safe construction belong to the field of geotechnology. In geotechnology, the soil (or rock) forms the subsoil and serves as construction material. It can also act as a load or form the load-bearing and stabilising material. In other words, geotechnology deals with the requirements that have to be given in order to use the soil (or rock) in the form of stable and functional civil engineering …