German ATV-DVWK-A 149E- Recording, classification and assessment of the condition of drainage...

G E R M A N A T V S T A N D A R D S

W A S T E W A T E R - W A S T E

ADVISORY LEAFLET ATV-M 149E

Recording, Classification and Assessment of the Condition of Drainage Systems outside Buildings

April 1999 ISBN 3-935067-30-5

Publishing Company for Wastewater, Waste and Water Pollution Control

Theodor-Heuß-Allee 17, D-53773 Hennef

Telephone: ++49-2242/872-120, Telefax: ++49-2242/872-100

E-mail: [email protected] - Internet: http://www.gfa-verlag.de

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Preparation The ATV Working Group 1.7.7 "Assessment of the Condition of Sewers and Drains", in November 1994, elaborated the Yellow Print of ATV Standard ATV-A 149 "Classification and Assessment of the Condition of Sewers and Drains". Within the scope of the participation procedure in accordance with ATV Standard ATV-A 400 "Principles for the Preparation of German ATV Standards" it was decided to publish this subject, not in the form of an ATV Standard but as an ATV Advisory Leaflet within the ATV German Standards Wastewater - Waste.

An ad hoc working group, consisting of members of ATV Working Group 1.7.7 "Assessment of the Condition of Sewers and Drains", and of ATV Working Group 1.5.4 "Rehabilitation and Renewal of Sewers and Drains" has continued this work.

At the same time CEN TC 165 "Wastewater Engineering" took up the subject "Classification and Assessment of Condition", whereupon the ad hoc working group was transformed into ATV Working Group 1.7.8 "Recording of the Condition and Assessment of Sewers and Drains", which has also produced the now presented Advisory Leaflet. ATV Working Group 1.7.8, continues, on the German side, to attend to the tasks within CEN TC 165.

The following have collaborated in ATV Working Group 1.7.7:

Dipl.-Ing. Lutz Barenthien, Düsseldorf Dipl.-Ing. Bruno Chwastek, Witten Dipl.-Ing. Hans-Bernd Derse, Düsseldorf Prof. Dr.-Ing. Max Dohmann, Aachen Dipl.-Ing. Hans Haas, Baunatal Dr.-Ing. Regina Haußmann, Aachen Klaus Janotta, Markt Schwaben Dr.-Ing. Martin Keding, Sankt Augustin Dipl.-Ing. Nikola Milojevic, München Dipl.-Ing. Bernd Wille, Wuppertal (Chairman)

Additional contributors:

Dieter Blome, Bielefeld (Chairman ATV WG 1.7.8) Dr.-Ing. Peter Drewniok, Leipzig Dipl.-Ing. Bernhard Fischer, Bonn Dipl.-Ing. Andreas Hartmann, Braunschweig Dr.-Ing. Renate Haußmann, Aachen Dipl.-Ing. Susanne Kentgens, Bochum Dipl.-Ing. Johannes Lohaus, Hennef (Chairman of the ad hoc WG) Prof. Dr.-Ing. Dietrich Stein, Bochum Dipl.-Ing. Holger Zinn-Naß, Kisdorf

All rights, in particular those of translation into other languages, are reserved. No part of this Advisory Leaflet may be reproduced in any form by photocopy, microfilm or any other process or transferred or translated into a language usable in machines, in particular data processing machines, without the written approval of the publisher.

GFA • Publishing Company for Wastewater, Waste and Water Pollution Control, Hennef 1999

Original German Edition produced by: DCM, Meckenheim

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Contents

Preparation 2

1. Notes for Users 4

2. Foreword 4

3. Objective and scope 5

4. Terms 5

5. Fundamentals 6

6. Procedural methods for condition classification and condition assessment 6

6.1 Condition classification 9 6.2 Condition Assessment 10 6.3 Priority list 11

7 Cost effects 11

Appendix 12

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1. Notes for Users This ATV Advisory Leaflet is the result of honorary, technical-scientific/economic collaboration which has been achieved in accordance with the principles applicable for this (statutes, Rules of Procedure of the ATV and ATV Standard ATV-A 400). Here, according to precedents, there exists an actual presumption that it is textually and technically correct and also generally recognised.

The application of this Advisory Leaflet is open to everyone. However, an obligation for application can arise from legal or administrative regulations, a contract or other legal reason.

This Advisory Leaflet is an important, however, not the sole source of information for correct solutions. With its application no one avoids responsibility for his own action or for the correct application in specific cases; this applies in particular for the correct handling of the margins described in the Advisory Leaflet.

2. Foreword Classification and assessment of the condition of drainage systems are handled differently. A generally valid procedure is not available. Therefore, for better execution and for mutual compatibility, models with comparable criteria should be applied.

In addition to construction and operation, inspection of existing wastewater discharge systems also belongs to the responsibility for communal wastewater disposal regulated under water law. The regulations introduced by individual Federal German States on the self-monitoring of sewage systems as well as the requirements on their operation and maintenance are to be observed. With this, identifiable constructional and operational conditions, which do not conform with the generally recognised status of technology, are to be removed within an appropriate period of time. With the execution of the measures, the functional capability of the sewer network as well as the protection of the groundwater and the soil have a special significance. If a positive danger exists for the groundwater or if an impairment of the groundwater has already been determined, the result is, already from wastewater disposal obligations, that the rehabilitation has to be undertaken without delay. Contamination of the groundwater within the meaning of § 324, § 324a StGB [German Criminal Code], as well as the actual fact of environmentally hazarding waste disposal in accordance with §326 StGB, are subject to penalties.

Every sewer condition has a different influence on keeping the groundwater clean and on the protection of the soil, maintenance of the function of wastewater systems, the stability of structural facilities etc. Due to the current status of knowledge on the actual effects, only a qualitative assessment is possible. This also should be take into account with the interpretation of the assessment results. Assessment procedures should continue to leave room for future knowledge.

The Advisory Leaflet presented here is divided into a general part and an application example in the appendix. The general part places principal requirements on the

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classification and assessment of condition which, independent of the assessment model, are to be observed within the sense of comparability of criteria. Other assessment models which at least fulfil the basic requirements, can also be applied.

3. Objective and Scope Object of this Advisory Leaflet is the classification and assessment of drainage systems within the framework of existing requirements, with the aim of laying down rehabilitation priorities.

A construction/rehabilitation programme can be produced on the basis of the priority list to be created, taking into account further criteria. For all those responsible for wastewater disposal it is recommended that the condition assessment model planned for application and also the timely sequence of the rehabilitation measures based on this should be agreed with the responsible water authority.

This Advisory Leaflet applies for existing, operating, accessible and non-accessible gravity sewers, shafts and structures of the local drainage system. It is equally applicable to normal, stormwater and combined sewers.

4. Terms Structural and operational condition The structural and operational condition results from the information from the inspection of the drainage system.

Condition class Standard for the classification of the structural and operational condition of sewers, shafts and structures of a local drainage system.

Condition classification Condition classification is the arrangement into condition classes of sewers, shafts and structures of a local drainage system based on their structural and operational condition.

Condition assessment Assessment of sewers, shafts and structures of a local drainage system based on the condition classification as well as on the hydraulic, environmentally relevant and, if required, other aspects.

Priority list Order of priority of the need for rehabilitation.

5. Fundamentals The requirements on a drainage system result from the laiddown legal details and technical rules and standards. In addition, the operator and /or the supervisory authority can place further requirements on the drainage system. The requirements and the assessment criteria on a drainage system must be created to be uniform, generally

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applicable and should be capable of duplication. This determination takes place only with the first registration, classification and assessment of the drainage system or with a later necessary increase of the requirement profile on the drainage system.

Prerequisites for a condition classification are the inspection and the description with the aid of condition symbols. The standard technique is optical registration of condition. In man-accessible sewers this takes place using direct visual inspection, in non-accessible ones using sewer television. Inspections should be carried out only by trained personnel, who meet the requirements of the "Gütegemeinschaft Herstellung und Instandhaltung von Entwässerungskanälen und -leitungen e.V. [Quality Association for the Production and Maintenance of Drains and Sewers]", Bad Hennef, Germany. The inspection is to have qualified monitoring.

If the inspection results so obtained are not sufficient then more extensive investigations such as, for example, leak testing, can be applied.

Further information on the execution of optical sewer inspection is contained in ATV Standard A 140E "Rules for the Operation of Sewers" and ATV Advisory Leaflet M 143E "Inspection, Repair, Rehabilitation and Replacement of Sewers and Drains; Part 2: Optical Inspection".

6. Procedural Methods for Condition Classification and Condition Assessment

Attention is to be paid that an assessment procedure within a drainage area is applied continuously and uniformly.

The general procedural method for condition classification and condition assessment cover the working steps:

- Determination of the actual condition

For the establishment of the actual condition the following are to be determined:

• the structural and operational conditions using, for example, optical inspection, using the knowledge from the operation of the sewer network etc.;

• the hydraulic efficiency through, for example, hydraulic calculations, measurements in the sewer network or through known operating defects etc.;

• the effects on the environment by, for example, taking into account the wastewater quality in the drainage system, the objects of normal and legal protection concerned (water protective zones, water law, soil, structural facilities) etc.

- Comparison with the requirements

Comparison with the requirements consists of the consecutive work steps condition classification and condition assessment.

• Condition classification

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Condition classification includes the categorisation of the sewers, shafts and structures of the local drainage system into condition classes based only on their structural and operational conditions.

• Condition assessment With condition assessment the hydraulic efficiency and the effects on the environment are linked logically and/or mathematically with the results of the condition classification.

The result of the condition assessment serves for the assessment of the rehabilitation need of the drainage system. It is a basis for the elaboration of comprehensive solutions.

In Fig. 1 the general procedure for condition classification and condition assessment is presented in the form of a flow diagram.

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Only with first registration or with increase of the requirement profile!

Fig. 1: General procedure for condition classification and condition assessment

Determination of theRequirements and Assessment Criteria

Determination of the actual condition

Structural and operational aspects

Hydraulic aspects

Environmental aspects

Registration of the structural and

operational condition

Determination of the hydraulic efficiency

Determination of the effects on the environment

Comparison with requirements

Condition classification

Condition assessment (logical and/or mathematical linking)

Priority list

Elaboration of comprehensive solutions

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6.1 Condition Classification

Basis for a classification of condition is the description of the structural and operational conditions of sewers, shafts and structures of the local drainage system. The inspection, description and classification/assessment must have a time relationship.

For condition classification the results of the registration of condition must be linked with additional information (e.g. sewer master data, results of previous inspections etc.). Here, plausibility is to be examined.

With regard to the ecological and economical significance, the examination of the inspection results, as well as the classification and assessment of condition, are to be carried out by a qualified specialist (e.g. engineer) who is independent of the inspection.

Condition classification and assessment must be checked by qualified engineering personnel for plausibility.

Condition classification must, dependent on the requirements on the sewer system, take into account the following assessment criteria:

• type of damage • extent of damage

The differentiation of both criteria can take place dependent on the respective requirements as well as on the available timeframe for the correction of damage.

For condition classification, the assessment of each individual damage is first necessary. A provisional classification can take place automatically using EDP. An individual breakdown of the damage must always be undertaken if a comprehensive condition description with the aid of status symbols is not possible. The provisional condition class determined using EDP is to be examined carefully.

On completion of the allocation of the condition class to the individual damage, a consolidation for the respective assessment unit (shaft, sewer section, structure) takes place. With this, the following criteria must be taken into account:

• the greatest individual damage in an assessment unit; • frequency and extent of further damage; • longitudinal extent of the individual damage.

If necessary, further criteria can be included.

With conditions which, according to the principle of concern, require instant treatment, immediate measures must be initiated.

For example, immediate measures must be initiated:

• with impairments to function which negate the operational function of the assessment unit,

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• with all structural damage in Water Protection Zone II and in the vicinity of the catchment area of medicinal and mineral springs, which place the sealing of the sewerage system even slightly in question,

• with the determination of an impairment to the groundwater through escaping wastewater,

• in all situations in which the static function of the body of the pipe is negated and danger of collapse of the assessment unit, neighbouring structures or the surrounding soil is threatened. Such situations are, for example:

- groundwater penetration carrying soil - determination of cavities in the vicinity of the sewer - road collapse in the vicinity of the sewer.

• with conditions which endanger life and limb of operational personnel.

6.2 Condition Assessment

Sewers, shafts and structures of the local drainage system, which are damaged and/or leaking, or show blockages, have effects on the environment. Through these the following protective aims are affected:

• maintenance of the purity of groundwater and protection of the soil; • maintenance of the function of the wastewater system; • stability of structural facilities.

The wastewater quality and the hydraulic conditions in the sewer section have a substantial influence on the named protective aims. These must be taken into account with the assessment of condition:

• for the assessment of the hydraulic condition the backwater level should be included, as the hydraulic pressure substantially determines the quantity of water escaping at leakage points. If the details are not available then details on abnormal occurrences or hydraulic calculations can be included as an aid. Furthermore, one must differentiate between existing and planned loading of the network.

• the possible quantity of escaping wastewater alone still does not determine the possible damage to the groundwater and soil. The properties of the wastewater are equally of decisive significance. The assessment of the wastewater quality should take place with the aid of the register of indirect dischargers. If this is not available or is still in the initial stages, details of the general development plan and the Wastewater Source Ordinance should be enlisted.

Further assessment criteria could be:

• position in the traffic area/type of road • cover height • location • traffic loading • accessibility • position related to groundwater level • permeability of the subsoil/soil properties • drainage system • design

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• age • geometry • material • significance of the sewer for the drainage system • position of the sewer related to water catchment areas

6.3 Priority List

Basis for the priority list is condition assessment. The priority list represents an order of priority for the need for rehabilitation with regard to the structural and operational aspects. The sequence of rehabilitation is thus not predetermined.

Further conditions, such as the following, should be taken into account for a practical construction programme:

• construction measures of other main contributors, private investors and those responsible for road construction;

• hydraulic or environmental defects; • combination of several differently assessed sewer sections into one measure; • technical traffic reasons; • structural improvements in the sewer network; • development measures etc.

7. Cost Effects The Advisory Leaflet presented here helps to save costs with rehabilitation (within the meaning of DIN EN 752, Part 5) of sewers, shafts and structures of the local drainage system.

Based on the description of the condition using status symbols with consequent application of this Advisory Leaflet within a drainage area, a classification according to the same criteria of the sewer condition into classes results, from which priority lists can be derived.

In this way the rehabilitation of the sewer network can then be implemented in the most economic manner in combination with other construction activities (road construction, development measures etc.) and with the requirements on hydraulic necessities.

Condition assessment can, in addition, be applied as basis for a dynamically developing asset assessment of the drainage system. In many cases the duration of depreciation of sewers, shafts and structures of the local drainage system can be extended which leads to reduction of the depreciation charges.

This planned procedure allows the sensible combination of rehabilitation projects on an economic scale with regard to their methods. The principle of carrying out rehabilitation tasks in the order of greatest cost effectiveness is the basis for the creation of the priority list.

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Appendix 1 Foreword 13

2 Terms within the meaning of the ATV classification and 13 assessment procedure

3 Fundamentals 14

4 Condition classification 20 4.1 Immediate measures 20 4.2 Condition classes 21 4.3 Condition points 21

5 Condition assessment 22 5.1 Assessment factors 23 5.1.1 Assessment factor for hydraulic conditions 23 5.1.2 Assessment factor for wastewater properties 23 5.1.3 Determination of assessment points 24 5.2 Determination of the assessment figure 25

6 Reclassification 27

7 Priority list 28

8 Plausibility test 28

9 Examples of application 29

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1 Foreword In this appendix a possible procedure for the conversion of the requirements of the general section is demonstrated. Other assessment models, which at least meet the principle requirements, can also be applied. The model presented here demonstrates the determination of a sequence of priorities for the necessary measures. In this connection it is heavily oriented on criteria under water law.

With the elaboration of the model, it has been assumed that the employment of EDP is necessary as an aid due to the amount of data, but that a completely automated processing is not possible and not practical as, for example, incomplete condition descriptions, complex damage descriptions and the necessity of examination for plausibility make processing by an engineer absolutely necessary.

The requirements and terms listed in the general section apply without restriction for the appendix and are not given more explicitly, unless additional explanation proves necessary from the structure of the model.

2 Terms within the Meaning of the ATV Classification and Assessment Procedure

Condition classification:

• Provisional condition classification: Arrangement of the assessment units into corresponding condition classes, with the aid of Tables 1 and 2, according to the scale of the structural and operation damage determined by the optical inspection whereby, as a rule, the greatest individual damage determines the condition class.

• Final condition classification a) Examination of the provisional condition classification carried out with the aid of

Tables 1 and 2 and upgrading classification in defined cases of exception. b) Determination of the condition points within the condition class in accordance with

the overall impression of the engineer, in particular according to the scale, position and closeness of damage.

Condition assessment:

• Assessment points: The structural and operational condition of an assessment unit are evaluated with the aid of assessment points. The assessment points result from the addition of condition points and a term, which takes into account the quality of the wastewater and hydraulics.

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• Assessment figures: The assessment figure takes into account the type of sewer and the object of protection/legal protection concerned. It results from the addition of terms for condition class, for the type of sewer and for the object of normal/legal protection concerned as well as the assessment or condition points.

Priority list:

The priority list results from the assessment figures sorted in descending order. It lays down a series of measures to be carried out in the ranking of condition classes, the type of sewer, the object of normal/legal protection as well as the assessment or condition points.

3 Fundamentals Prerequisite for the condition classification is the inspection and the description with the aid of condition symbols.

For the condition assessment additional details on the drainage system are necessary on:

• the hydraulic loading, • the wastewater properties, • the position in the water protection areas,

catchment areas for medicinal and mineral springs as well as other water rights, • the position of the groundwater level. The strict classification of an individual damage and the position in a class creates the prerequisite for comparability as well as an authorised enforcement. Five condition classes are assumed. For rehabilitation the following periods are offered:

Condition Class 0 = immediate Condition Class 1 = short-term Condition Class 2 = medium-term Condition Class 3 = long-term Condition Class 4 = no requirement for treatment

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Inspector

Engineer

Reclassification necessary?

Fig. 1: Procedural method with condition classification and assessment

Condition description with the aid of

optical inspection

Provisional condition classification

Tables 1 and 2

Final condition classification 1) Examination of the provisional condition classification and possible classification upgrading 2) Allocation of condition points

Determination of the assessment points

Hydraulics Wastewater quality

Determination of assessment figure Object of normal/legal protection

No

Yes

Reclassification

Priority list

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4 Condition Classification The condition description carried out with the aid of condition symbols in the television vehicle by trained inspectors as well as the details on the extent of the damage result, with the assistance of Tables 1 and 2, in a provisional division of damage into condition classes.

The limits given in Tables 1 and 2 for division into classes allows a provisional condition classification using EDP.

Within the scope of engineer processing the provisional condition class determined under Tables 1 and 2 is to be carefully checked. As a rule the greatest individual damage determines the condition class (CC). In defined cases of exception another higher condition class (from CC3 to CC2, from CC2 to CC1, from CC1 to CC0) can be given, for example with a certain accumulation of damage of the same severity otherwise also, insofar as this, for example, is considered to be necessary due to a damage picture insufficiently described with condition symbols. An individual classification of a damage must always be carried out if a condition description is not possible using condition symbols.

4.1 Immediate Measures

With conditions which, according to the principle of concern, require prompt action, immediate measures are to be initiated.

In addition to general description of the damage, which determine the immediate measures, the condition description using symbols also leads to Condition Class 0 in accordance with Table 3.

Table 3: Conditions which lead to classification in Condition Class 0

Condition group pipeline Symbol/numerical suffix

Visible leakage

Obstacle to flow (general sedimentation, projecting flow obstacle, solidified deposits)

Flow obstacle (incrustation, ingrowing roots)

Corrosion Complete corrosion

Deformation of flexible pipes

Cracks Pipe rupture

M: (at 3rd position) running inflow with material charge

> 50 % cross-section reduction

> 30 % cross-section reduction

Pipe walls

> 40 %

> 10 mm mean ∅ more than 5 cm

Additional individual missing items with structures

Comp. Table 2

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4.2 Condition Classes

Condition Classes 1, 2 and 3 cover the structural and operational conditions to be assessed. Assessment units, which have no recognisable or only minor faults, are classified in Condition Class 4. Minor faults can be, for example, dimensional inaccuracies, scratches, chipping of glazing or similar.

The characteristics of the condition classes can be found in Tables 1 and 2.

The classification into condition classes takes place using symbols at the 3rd position (details on density) and with the aid of numerical suffixes (details on scale of damage) in accordance with Table 4.

Table 4: Classification into condition classes using symbols at the 3rd position.

Symbol at the 3rd position Condition class

E: penetrating water visible

B: ground visible

A: visible escape of water

Condition Class 1

F: moisture visible Condition Class 2

The limitation of the condition classes due to their numerical suffix is in accordance with Tables 1 and 2. If, due to a symbol at the 3rd position, the classification results produces a different condition class to the classification then the damage is always to be allocated the highest condition class.

4.3 Condition Points (CP)

Within one condition class there are respectively 100 points available in order to take into account the scale of the damage and the position of the damage as well as the damage density in the sewer section. Below are some criteria for the determination of the initial point summarised as examples.

Initial point in the left-hand field of the condition class

Initial point in the right-hand field of the condition class

multiple damage

position of damage: pipe sole

area with damage long

single damage

position of damage: pipe crown

area with damage short

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points

Condition

400

300

200

100 1 2 3 4

Condition class

Fig. 2: Condition points dependent on condition class

Table 5: Condition points dependent on condition class

Condition class Condition points

1 301 - 400

2 201 - 300

3 101 - 200

Determination of the point number within a condition class is to take place, in addition to these criteria, based on the experience of a qualified specialist. An algorithm, which supports this activity, can also be used.

Here it is to be noted that, within one condition class, only the maximum number of points is to be achieved.

5 Condition Assessment Sewers, shafts and structures of the local drainage system which are damaged and/or obstructed, have effects on the environment. Through this various protective aims are involved. Each of the characteristics described has a different influence on the protective aims and would, therefore, need to be weighted accordingly. Due to a lack of information on the actual effects of the damage on the respective protective aim a weighting in the models described here is not undertaken. The possible effects on the environment are assessed with the aid of assessment factors which take into account the hydraulic conditions in the drainage system and the characteristics of the wastewater. With this, a fictional loading of the soil and groundwater due to the escaping wastewater load is assumed. This protective aim is always to be taken into account if a sewer section has conditions which do not exclude exfiltration. For example, infiltration observed with the aid of TV inspection does not exclude an exfiltration of wastewater with a lower groundwater level.

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5.1 Assessment Factors

5.1.1 Assessment Factor for Hydraulic Conditions

The condition of a drainage system alone still does not allow any conclusions about the hazarding of the groundwater and soil resulting from it. There is a greater danger from an exfiltrating drainage system which is frequently overloaded than from a drainage system which is always only filled to a lesser degree. These circumstances are taken into account with the aid of assessment factors for the hydraulic conditions.

To determine the hydraulic assessment factor the height of backup should be used as the hydraulic pressure essentially determines the quantity of escaping water at leaks. If these details are not available then details from abnormal occurrences or hydraulic calculations can be used as an aid.

The overall performance (Qmax/Qfull) alone is not sufficiently expressive as, with backup events, even sewer sections whose overall performance is well below 100 % can be impounded or overdammed.

The following assessment factors H are laid down for the hydraulic conditions:

Assessment factor H = 1.0 − Mathematically verified impounding in sewers for the forecast state based on

additional identified but still undeveloped areas. − Mathematically unverified impounding in sewers for the actual state.

Assessment factor H = 1.1 − Mathematically verified impounding for forecasts in sewers based on a development

density.

Assessment factor H = 1.2 − Mathematically verified impounding in sewers with actual state.

Assessment factor H = 1.3 − Determined impounding and overdamming occurrences in sewers (complaints from

residents, screwed down manhole covers). − Mathematically verified overdamming in sewers.

5.1.2 Assessment Factor for Wastewater Properties

The possible quantity of escaping wastewater alone still does not determine the possible harm to groundwater and soil. The properties of the wastewater are equally of significance. Therefore, for the classification of quality, assessment factors are also applied. The division of wastewater into groups take place in a simplified manner based on the source of the wastewater, as a classification on the basis of analytical examinations, which, of necessity, has to be very comprehensive, is economically unjustifiable and also cannot be applied across the board at every site and, in each individual case, would require a specialist technical assessment.

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The classification of assessment factors should take place with the aid of the indirect discharger register. If this is not available or is only being developed, then details of the construction supervision planning and the wastewater source ordinance should be utilised.

The following assessment factors for wasterwater properties are laid down based on the subsequent quality characteristics:

Assessment factor Q = 1.0 − Slightly loaded stormwater in a separate sewer system e.g. from the surface drainage

of a purely residential area.

Assessment factor Q = 1.1 − Wastewater from a purely residential area and combined areas as well as stormwater

from surface drainage of main roads and heavily contaminated traffic areas.

Assessment factor Q = 1.2 − Wastewater which, to a slight extent, is characterised by commerce and industry or

by concerns which fall under the (German) Wastewater Source Ordinance.

Assessment factor Q = 1.3 − Wastewater which, to a considerable degree, is characterised by commerce and

industry or by concerns which fall under the (German) Wastewater Source Ordinance.

5.1.3 Determination of Assessment Points

Assessment points (AP) are calculated from the following equation:

1]100

1) - (CP[INT 69 200 H Q 100 CP AP −•++••+=

where: AP = assessment points CP = condition points Q = wastewater factor H = hydraulic factor INT = integer function; a function which eliminates positions after the decimal point e.g. INT (2.9) = 2

The assessment points, according to the above equation, result as follows:

Condition Class 3 401 - 569 Condition Class 2 570 - 738 Condition Class 1 739 - 907

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Fig. 3: Assessment points dependent on condition class

5.2 Determination of the Assessment Figure

Exfiltrating drainage systems in water protection zones infringe upon a higher object of normal/legal protection than in areas without water procurement. Concern over the groundwater is to be given significantly greater value than disruption of the wastewater operation due to faults, which can be repaired using the technical means of the sewer operation.

The following areas are demarcated from one another:

Catchment Area IIIa The drainage system lies in Water Protection Zone (WPZ) IIIa.

Catchment Area IIIb The Drainage system lies in Water Protection Zone IIIb.

Other water rights The drainage system does not lie in a water protection zone, there are, however, water rights, e.g. facilities for own water supply.

Remaining exfiltration The drainage system does not lie in a water protection zone, normal water rights are not affected. Due to the escaping wastewater either the groundwater or the surrounding soil can be hazarded.

According to current information one has to reckon particularly with exfiltration in the pipeline trench with:

− damage of the Condition Classes 0, 1 or 2 and − position of the damage in the pipe sole or below the water plain in the dimensioning

case. − Pipe sole above the groundwater level or in the alternate area.

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Transportation into the surrounding soil is primarily to be expected with very permeable, low absorption soils (gravel, sand).

Infiltration The drainage system lies in the groundwater. Groundwater enters the drainage system at leakage points.

Operation The function of the drainage system, i.e. the harmless discharge of wastewater is prejudiced, can, however, at least temporarily, be re-established through operational measures (cutting of root ingrowth, removal of deposits, encrustation etc.).

If all or almost all sewers lie in one of these areas, a further differentiation can take be undertaken, e.g. with regard to the type of soil or the separation to the groundwater.

To take into account these objects of normal/legal protection (NLP) as well as the type of sewer and the condition class the assessment figure is introduced.

The assessment figure (AF) is calculated according to the following equation:

AP10NLP10TS10CCAF 3f

4f

5f +•+•+•=

With: AF = assessment figure CCf = condition class factor KAf = sewer type factor NLPf = object of normal/legal protection factor AP = assessment points, in case the assessment points cannot be determined, the condition points (CP) can be used

Table 6: Condition class factor

Condition class factor

Condition class CCf

1 3

2 2

3 1

Table 7: Sewer type factor

Sewer type factor

Sewer type STf

Normal/ Combined sewer

5

Stormwater sewer 2

Table 8: Object of normal/legal protection factor

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Object of normal/legal protection factor

Object of normal/legal protection NLPf

Water protection zone IIIa 5

Water protection zone IIIb 4

Other water rights 3

Remaining exfiltration 2

Infiltration 1

Operation 0

The assessment figure classifies the drainage systems according to their condition class, the sewer type, the object of normal/legal protection affected and the assessment points.

6 Reclassification Considering the protection aims, priorities can be shifted in justified cases. Examples of this could be:

• downgrading of an exfiltrating stormwater sewer which drains a purely residential area correctly.

• downgrading of sewers whose construction (redundant pipe, double piping etc.) takes into account in a particular manner the object of normal/legal protection.

• upgrading of sewers which hazard the groundwater in a particular manner.

The down/upgrading must, however, be regulated uniformly for the complete drainage area.

The up/downgrading by one condition class ensues, for reasons of clarity of reclassification, from the results according to the following equations:

Upgrading (CC3→CC2, CC2→CC1):

Recalculation of the assessment figure: AFnew = AFold + 90,000

Downgrading (CC1→CC2, CC2→CC3):

Recalculation of the assessment figure: AFnew = AFold - 90,000

7 Priority List The priority list results from the assessment figures sorted in descending order. It lays down a series of measures to be carried out in the order of condition classes, sewer type, object of normal/legal protection as well as the assessment or condition points.

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8 Plausibility Test In order to be able to check and interpret the assessment figures given in the priority list, the ratings carried out in the condition assessment and the up/downgrading carried out in the reclassification can be read from the assessment figure:

Figure Function

1. - current condition class

2. - sewer type

- up/downgrading

3. - object of normal/legal protection

4./5./6. - assessment or condition points - condition class allocated in the

final condition classification (it is the same as the current condition class, if no reclassification is undertaken

Example:

1 3 2 572

1st Figure 2nd Figure 3rd Figure 4th/5th/6th Figure Condition

class Sewer type Reclassified Object of

normal/legal protection

Assessment points

Condition class

3 1 6 downgraded 5 WPZ IIIa 739 - 907 1 2 2 5 Normal/comb.

sewer none 4 WPZ IIIb 570 - 738 2

1 3 4 downgraded 3 Other water rights

401 - 569 3

3 downgraded 2 Remaining exfiltration

Condition points

Condition class

2 Stormwater sewer none 1 Infiltration 301 - 400 1 1 downgraded 0 Operation 201 - 300 2 101 - 200 3

Statement: Here one is concerned with an exfiltrating (3rd figure) stormwater sewer (2nd figure), which has the current Condition Class 3. It has been downgraded from Condition Class 2 to the Condition Class 3 (2nd figure, 4th/5th/6th figures).

9 Application Examples Example 1:

Sewer section graphics Protocol No. :1 Sewer section No. :1 Sewer system :KM (combined)

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from shaft :1 to shaft :2 Direction of flow :counter Nominal width :300 Pipe material :vitrified clay Scale :1:500 Videotape No. :1185 Video cassette :1185

Dist. Report 1

⊕ 000.0 Start of section

003.5 Start of damage axial crack, crown, size of crack [0-99 mm] = 2.0

004.5 End of damage,

012.5 Start of damage axial crack, crown, size of crack

[0-99 mm] = 1.0 014.0 End of damage, 017.0 Branch, right-hand abutment

022.5 Start of damage, ⊕ axial crack, sole, size of crack

2 [0-99 mm] = 2.0 023.0 End of damage, 027.6 End of section

Local conditions

Water protection zone: IIIa Hydraulic conditions: mathematically verified impounding for the prognosis based on

the development density − H = 1.1 - see 4.1.1

Wastewater combined wastewater from residential areas characteristics − Q = 1.1 - see 4.1.2


Based on the protocol and the video recordings.

The greatest individual damage within a section determines the condition class (see 3.3).

Classification is according to Table 1

1. 2. 3. 4. 5. Position

R L - U 2 mm Condition Class 2

Allocation of condition points takes place with the aid of Fig. 2.

Two of the three sets of damage are to be classified as Condition Class 2 (cracks 2 mm ≤ x < 5 mm). However, they lie at the lower boundary of the condition class and

ATV-M 149E

April 1999 30

are comparatively limited. Therefore, as a result, entry in Fig. 2 is in the right-hand zone of Condition Class 2.

Point count: 201


Points from Fig. 2 with H = 1.1 and Q = 1.1:

591=−−

•++••+= 1])100

1201[INT(692001.11.1100201AP

Determination of assessment figure

Where − CCf = 2, Condition Class 2 − STf = 5, combined sewer − NLPf = 5, WPZ IIIa

and AP = 591 results in an AF value of:

255591=+•+•+•= 5911051052 AF 34510

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Example 2:

Sewer section graphics Protocol No. :2 Sewer section No. :2 Sewer system :KM (combined) from shaft :3 to shaft :4 Direction of flow :counter Nominal width :400 Pipe material :vitrified clay Scale :1:500 Videotape No. :1185 Video cassette :1185

Dist. Report 3


003.9 Branch, right-hand abutment 004.5 Crack in area of connection piece left-hand abutment Crack size [0-99 mm] = 1.0 012.3 Crack in area of connection piece right-hand abutment Crack size [0-99 mm] = 1.0

019.9 Branch, left-hand abutment

033.0 Flow obstacle, root ingrowth, sole, cross-section reduction [0-99 %] = 10.0

⊕ 037.1 End of section 4

Local conditions

Water protection zone: IIIb Hydraulic conditions: determined impounding and overdamming events

− H = 1.3 - see 4.1.1 Wastewater combined wastewater from residential areas characteristics − Q = 1.1 - see 4.1.2




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1. 2. 3. 4. 5. Position

H P - U 10 % Condition Class 2


Greatest individual damage is the root ingrowth which is to be classified as Condition Class 2. The cracks in the area of the connection piece justify solely Condition Class 3. Entry into Fig. 2 therefore takes place in the right-hand area of Condition Class 2.

Point count: 201



613=−−

•++••+= 1])100

1201[INT(692001.11.3100201AP


Where − CCf = 2, Condition Class 2 − STf = 5, combined sewer − NLPf = 0, operation


250613=+•+•+•= 13105 61001052 AF 34

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April 1999 33

Example 3:

Sewer section graphics Protocol No. :3 Sewer section No. :3 Sewer system :KR (stormwater) from shaft :5 to shaft :6 Direction of flow :counter Nominal width :300 Pipe material :concrete Scale :1:500 Videotape No. :1185 Video cassette :1185

Dist. Report 5

⊕ 000.0 Start of section 004.8 Start of damage, axial crack, left-hand abutment size of crack, [0-99 mm] = 1.0 005.8 End of damage, 006.0 Start of damage, axial crack, sole, size of crack, [0-99 mm] = 1.0 006.4 End of damage, 007.9 Start of damage, axial crack, crown, size of crack [0-99 mm] = 5.0, axial crack right-hand abutment, water penetrating 009.5 End of damage,

. 011.9 Closed branch, right-hand abutment 022.2 Start of damage, axial crack, crown size of crack, [0-99 mm] 1.0 025.5 Closed branch,

right-hand abutment 029.5 Closed branch,

left-hand abutment 031.5 End of damage 036.1 Start of damage, axial crack, moisture visible, sole, size of crack, [0-99 mm] = 1.0 037.1 End of damage ⊕ 045.6 End of section 6

Local conditions

Water protection zone: IIIa, infiltrating, sewer permanently in groundwater Hydraulic conditions: impounding not verified mathematically

− H = 1.0 - see 4.1.1 Wastewater stormwater in a separate sewer from surface drainage from a characteristics residential area − Q = 1.1 - see 4.1.2

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April 1999 34





1. 2. 3. 4. 5. Position

R L E R 5 mm Condition Class 1


There are cracks in the section which run over several metres. At one point there is penetrating water, at another point moisture is visible. Entry into Fig. 2 is in the central zone.

Point count: 350



798=−−

•++••+= 1])100

1350[INT(692001.11.0100350AP


Where − CCf = 3, Condition Class 1 − STf = 2, stormwater sewer − NLPf = 1, infiltration

and AP = 798 results in a AF value of:

321798=+•+•+•= 7981011023 AF 34510

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Example 4:


Dist. Report 2

⊕ 000.0 Start of section 005.0 Obstacle to flow, sole, root ingrowth cross-section reduction, [0-99 %] = 5.0 007.0 Obstacle to flow, sole, root ingrowth cross-section reduction, [0-99 %] = 5.0 008.0 Obstacle to flow, sole, root ingrowth cross-section reduction, [0-99 %] = 5.0 012.0 Obstacle to flow, sole, root ingrowth cross-section reduction, [0-99 %] = 5.0 015.0 Branch, right-hand abutment 017.5 Obstacle to flow, root ingrowth, complete circumference cross-section reduction, [0-99 %] = 30.0

027.5 Branch, left-hand abutment

⊕ 032.7 End of section 3

Local conditions

Water protection zone: IIIb Hydraulic conditions: overdamming events

− H = 1.3 - see 4.1.1 Wastewater Combined wastewater from characteristics residential area − Q = 1.1 - see 4.1.2




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1. 2. 3. 4. 5. Position

H P - - 30 % Condition Class 1


The relevant defect is to be classified in the boundary zone to immediate measures, the other defects are, up to now, still slight. Entry into Fig. 2 therefore takes place in the left-hand area of Condition Class 1,

Point count: 380



861=−−

•++••+= 1])100

1380[INT(692001.11.3100380AP


Where − CCf = 3, Condition Class 1 − STf = 5, combined sewer − NLPf = 0, operation


350861=+•+•+•= 8611001053 AF 34510

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Example 5:


Dist. Report 4


003.1 Start of damage, axial crack, sole, size of crack [0-99 mm] = 4.0

009.5 End of damage 016.5 Branch, right-hand abutment 021.5 Start of damage, axial crack, sole, size of crack ⊕ [0-99 mm] = 4.0 5 022.6 End of damage 023.4 End of section

Local conditions

Water protection zone: none, remaining groundwater

Hydraulic conditions: determined impounding and overdamming events − H = 1.3 - see 4.1.1

Wastewater wastewater from characteristics commerce and industry − Q = 1.3 - see 4.1.2




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1. 2. 3. 4. 5. Position

R L - U 4 mm Condition Class 2


Two long cracks are determined in the relatively short sewer section. Here the relevant damage is in the sole. In accordance with 3.3 entry is therefore into the left-hand area of Condition Class 2 in Fig. 2.

Point count: 280



718=−−

•++••+= 1])100

1280[INT(692001.11.0100280AP


Where − CCf = 2, Condition Class 2 − STf = 5, normal sewer − NLPf = 3, residual groundwater


253718=+•+•+•= 7181031052 AF 34510

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Priority list

The assessment figures for the examples are listed below:

Example 1 Example 2 Example 3 Example 4 Example 5

255591 250613 321798 350861 253718

Sorting these assessment figures in descending order there results the following priority list:

Priority list

Example 4 Example 3 Example 1 Example 5 Example 2

350861 321798 255591 253718 250613

Assessment figures sorted in descending order ≡ Priority List

Table 1: Limitation of condition classes for the pipeline Immediate measure

Condition Class 0

Condition Class 1

Condition Class 2

Condition Class 3

Condition Class 4 Condition type Condition specification Condition description Condition description Condition description Condition description Condition description Classification based on symbols at the 3rd

position, if the numerical suffix does not demand a higher classification

All damage M E,A,B F

1 Branch Prejudiced part of cross-section

A - D

Branch blocked

All

-

-

-

-

AN Branch not correctly installed Assessment possible only in combination with additional description Measured/estimated width AP

AR Root ingrowing through branch

Crack in branch X ≥ 30 %

X ≥ 10 mm 20 % ≤ x < 30 %

5 mm ≤ x < 10 mm 10 % ≤ x < 20 % 2 mm ≤ x < 5 mm

X < 10 % 0.5 mm ≤ x < 2 mm

- x < 0.5 mm

2 Pipe fracture Measured/estimated area

BA BC BS BT BW

Missing piece of pipe at shaft,

connection to structure Missing piece of pipe in area of connection

Missing fragment Collapse

Hole, missing piece of pipe wall

X ≥ 25 cm2

X ≥ 25 cm2

X ≥ 25 cm2

Immediate

X ≥ 25 cm2

X < 25 cm2

X < 25 cm2

X < 25 cm2

-

X < 25 cm2

- - - - -

- - - - -

- - - - -

3 Corrosion C - CC CK CM

Internal corrosion

Corrosion in pipe connection Corrosion of brickwork

Corrosion of jointing mortar

- - - -

13,33 13,33

all 33

12,22,32 12,22,32

- 32

11,21 11,21

- -

- - - -

4 Deformation of flexible pipes Measured/estimated change to diameter

D -

Deformation

40 % ≤ X

20 % ≤ x < 40 %

10 % ≤ x < 20 %

6 % < x < 10 %

x ≤ 6 %

5 Bad connection F - - Wastewater in stormwater sewer - faeces visible

Stormwater in normal sewer, permanent water inflow

. -

6 Obstacle to flow Measured/estimated

H -

General obstacle

X ≥ 50 %

35 % ≤ x < 50 %

20 % ≤ x < 35 %

5 % ≤ x < 20 %

x < 5 %

Impaired part of cross-section HDG HDS

Sedimentation (debris) Sedimentation (sand) must be removed before carrying out inspection

HE HF HG HI HK HM HP HS HZ

Intruding obstacle Solidified deposits

Intruding sealing ring Encrustation

Intruding brickwork Intruding sealant

Root ingrowth Intruding piece

Crossing foreign pipeline/cable

X ≥ 50 % X ≥ 50 %

X ≥ 30 %

- X ≥ 50 % X ≥ 30 %

- -

35 % ≤ x < 50 % 35 % ≤ x < 50 %

all 20 % ≤ x < 30 %

- 35 % ≤ x < 50 % 20 % ≤ x < 30 %

all all

20 % ≤ x < 35 % 20 % ≤ x < 35 %

10 % ≤ x < 20 %

all 20 % ≤ x < 35 % 10 % ≤ x < 20 %

- -

5 % ≤ x < 20 % 5 % ≤ x < 20 %

5 % ≤ x < 10 %

- 5 % ≤ x < 20 %

x < 10 % - -

x < 5 % x < 5 %

x < 5 %

- x < 5 %

- - -

7 Sewer rehabilitation KN Sewer rehabilitation not carried out correctly Assessment possible only in combination with additional description 8 Deviation of position

ds: wall thickness of sewer pipe LB LH LL LV

Bending outwards, bowing downwards

Displacement in horizontal direction Axial displacement

Displacement in vertical direction

x ≥ 15 % of ∅ x ≥ 15 cm

x ≥ 15 % of ∅

x ≥ 100 % of ds1)

10 cm ≤ x < 15 cm x ≥ 100 % of ds

1)

75 % ≤ x < 100 % of ds1)

5 cm ≤ x < 10 cm 75 % ≤ x < 100 % of ds

1)

25 % ≤ x < 75 % of ds1)

2 cm ≤ x < 5 cm 25 % ≤ x < 75 % of ds

1)

x < 25 % of ds1)

x < 2 cm x < 25 % of ds

1) 9 Cracks

Measured/estimated RC RL RQ

Crack in area of connection

Longitudinal crack Transverse crack

10 mm ≤ x 10 mm ≤ x 10 mm ≤ x

5 mm ≤ x < 10 mm 5 mm ≤ x < 10 mm 5 mm ≤ x < 10 mm


0.5 mm ≤ x < 2 mm 0.5 mm ≤ x < 2 mm 0.5 mm ≤ x < 2 mm

x < 0.5 mm x < 0.5 mm x < 0.5 mm

RS RX

Fragmentation Cracks radiating from a point

Individual case consideration, at least as other cracks Individual case consideration, at least as other cracks

10 Connection pieces Impaired part of cross-section

S - D SE

Connection piece blocked

Connection piece protruding

All

x ≥ 50 %

-

35 % ≤ x < 50 %

-

20 % ≤ x < 35 %

-

5 % ≤ x < 20 %

-

x < 5 % SN Connection piece not correctly installed Assessment possible only in combination with additional description SO Connection piece externally proud Classification based on 3rd position - - Impaired part of cross-section

Measured/estimated SP SR

Root ingrowth through connection piece Crack in connection piece

x ≥ 30 % x ≥ 10 mm

20 % ≤ x < 30 % 5 mm ≤ x < 10 mm

10 % ≤ x < 20 % 2 mm ≤ x < 5 mm

x < 10 % 0.5 mm ≤ x < 2 mm

- x < 0.5 mm

Table 1: Limitation of condition classes for the pipeline (continued) Immediate measure

Condition Class 0

Condition Class 1

Condition Class 2

Condition Class 3

Condition Class 4 Condition type Condition specification Condition description Condition description Condition description Condition description Condition description 11 Missing component TK Missing brickwork Individual case consideration

12 Visible leaks UA UC UW

Leaking generally General leaks General leaks

Classification based on 3rd position Classification based on 3rd position Classification based on 3rd position

- - -

- - -

13 Mechanical wear according to numerical coding

V - VC

General mechanical wear

Mechanical wear at pipe connection

- -

13,33 13,33

12,22,32 12,22,32

11,21 11,21

- -

14 Other damage W - G Large, heavy water infiltration All - - - - 1) Wall thickness of outgoing sewer

Table 2: Limitation of condition classes for shafts and structures Immediate measure

Condition Class 0

Condition Class 1

Condition Class 2

Condition Class 3




1 Connection Prejudiced part of cross-section

A - D AE

Connection blocked

Protruding connection

All

x ≥ 50%

-

35% ≤ x < 50%

-

20% ≤ x < 35%

-

5% ≤ x < 20%

-

x < 5% AN Incorrectly constructed connection Individual case consideration 2 Fracture

Measured/estimated area BC BS

Missing piece of wall in area of connection

Missing fragment

Individual case consideration Individual case consideration

BT Collapse All - - - - BW Missing part of wall Individual case consideration 3 Corrosion

C - CC CK CM

Internal corrosion, general

Corrosion in area of connection Corrosion of brickwork

Corrosion of jointing mortar

- - - -

13,33 13,33

All 33

12,22,32 12,22,32

- 32

11,21 11,21

- -

- - - -

4 Deformation of flexible structures Measured/estimated Change to diameter of structure Defect

D- -W

Deformation of structure walling

x ≥ 40 %

20 % ≤ x < 40 %

10 % ≤ x < 20 %

6 % < x < 10 %

x ≤ 6 %

Signified faulty but still usable D General defect Individual case consideration D- -B

D- -C D- -D D- -F D- -G D- -H D- -I D- -K D- -L D- -M D- -N D- - Q D- -S D- -T D- -V

Abutment defect Compensating ring defect

Manhole cover defect Dirt trap defect Channel defect

Shaft neck, cone defect Shaft ring defect

Cover (cover plate) defect Ladder defect

Superstructure defect Railing defect Fixture defect

Step iron defect Step defect

Entry aid defect

- - - - - - - - - - - - - - -

- - X - - - - X X - X - X X X

X - - - X - - - - - - - - - -

- X - X - X X - - X - X - - -

- - - - - - - - - - - - - - -

5 Faulty connection F - - Wastewater in stormwater sewer - faeces visible

Stormwater in normal sewer permanent water inflow

- -

6 Obstacles Measured/estimated Impaired part of cross-section of outgoing sewer (Obstacle which does not effect the runoff cross-section; Individual case consideration

H - HDG HDS HE HF HI

General obstacle

Sedimentation (debris) Sedimentation (sand)

Intruding obstacle to flow Solidified deposits

Encrustation

x ≥ 50 % x ≥ 50 % x ≥ 50 % x ≥ 50 % x ≥ 50 % x ≥ 30 %

35% ≤ x < 50 % 35% ≤ x < 50 % 35% ≤ x < 50 % 35% ≤ x < 50 % 35% ≤ x < 50 % 20% ≤ x < 30 %

20 % ≤ x < 35 % 20 % ≤ x < 35 % 20 % ≤ x < 35 % 20 % ≤ x < 35 % 20 % ≤ x < 35 % 10 % ≤ x < 20 %

5 % ≤ x < 20 % 5 % ≤ x < 20 % 5 % ≤ x < 20 % 5 % ≤ x < 20 % 5 % ≤ x < 20 % 5 % ≤ x < 10 %

x < 5 % x < 5 % x < 5 % x < 5 % x < 5 % x < 5 %

HK Protruding brickwork All HP

HZ Root ingrowth

Crossing foreign pipeline/cable x ≥ 30 %

- 20% ≤ x < 30 %

All 10 % ≤ x < 20 %

- x < 10 %

- - -

7 Sewer rehabilitation KN Sewer rehabilitation not correctly carried out Assessment possible only in connection with additional description 8 Deviation of position [cm] Negative mismatch of the base in runoff LH Horizontal mismatch Individual case consideration LL Axial displacement X ≥ 30 cm 20 cm ≤ x < 30 cm - - -

Table 2: Limitation of condition classes for shafts and structures (continued) Immediate measure

Condition Class 0

Condition Class 1

Condition Class 2

Condition Class 3




9 Cracks Measured/estimated width

R - RC RL

General crack

Crack in area of connection Horizontal crack

10 mm ≤ x 10 mm ≤ x 10 mm ≤ x



0.5 mm ≤ x < 2 mm 0.5 mm ≤ x < 2 mm 0.5 mm ≤ x < 2 mm

X < 0.5 mm X < 0.5 mm X < 0.5 mm

RS Formation of fragments Individual case consideration, at least as other cracks RV Vertical crack 10 mm ≤ x 5 mm ≤ x < 10 mm 2 mm ≤ x < 5 mm 0.5 mm ≤ x < 2 mm X < 0.5 mm RX Cracks radiating from a point Individual case consideration, at least as other cracks 10 Pipe connection, connection to private

property, road gully Impaired part of cross-section of the outgoing

S - D SE

Connection blocked Intruding connection

All x ≥ 50 %

-

35 % ≤ x < 50 %

-

20 % ≤ x < 35 %

-

5 % ≤ x < 20 %

-

x < 5 % sewer otherwise consideration by individual SN Incorrectly produced connection Individual case consideration X < 5 % case SO Connection appears outside Classification based on 3rd position - - SP

SR Root ingrowth through connection

Crack in inlet x ≥ 30 %

x ≥ 10 mm 20 % ≤ x < 30 %

5 mm ≤ x < 10 mm 10 % ≤ x < 20 % 2 mm ≤ x < 5 mm

5 % ≤ x < 10 % 0.5 mm ≤ x < 2 mm

X < 5 % x < 0.5 mm

11 Missing component T-

Missing component

Individual case consideration

T - - B T - - C T - - D T - - F T - - G T - - K T - - L

Missing abutment Missing compensating ring

Missing manhole cover Missing dirt trap Missing channel

Missing (cover plate) Missing ladder

- - X - - X X

- - - - - - -

X - - - X - -

- X - X - - -

- - - - - - -

T - - M Missing superstructure component Individual case consideration T - - N Missing railing X - - - - T - - Q Missing fitting Individual case consideration T -- S

T -- T T --V

Missing climbing iron Missing step

Missing entry aid

X X -

- - X

- - -

- - -

- - -

TK Missing brickwork Individual case consideration 12 Visible leaks

U - UC

Leaks general

Shaft ring connection leak

Classification based on 3rd position Classification based on 3rd position

- -

- -

13 Mechanical wear V - VC

- -

13,33 13,33

12,22,32 12,22,32

11,21 11,21

- -

14 Other damage W - G Large, heavy water infiltration All - - - - 1) Wall thickness of outgoing sewer

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