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A multi-criteria approach for asset management of waste water networks. D2-Decision Deck project Workshop, March 8-9, 2007 , University of Luxembourg. Amir NAFI, Caty WEREY. Joint Unit Research in Water Utilities Management Cemagref-Engees 1 quai Koch 67070 Strasbourg, France. Context.

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A multi criteria approach for asset management of waste water networks l.jpg

A multi-criteria approach for asset management of waste water networks

D2-Decision Deck project

Workshop, March 8-9, 2007 , University of Luxembourg.

Amir NAFI, Caty WEREY

Joint Unit Research in Water Utilities Management Cemagref-Engees

1 quai Koch 67070 Strasbourg, France.


Slide2 l.jpg

Context

Data

Encodage

REREAU

Proposition

Conclusion

Context

152 sewerage utilities

Joint international conference on computing and decision making in civil and building engineering - june 14-16 2006 - Montreal


Slide3 l.jpg

Data on the pipe and its environment

5 100 km

(4 600 km waste water)

Defects noticed by CCTV inspectionsunder « local » codification

32 232 inspections

89 311 defects

Context

Data

Encodage

REREAU

Proposition

Conclusion

Sewers inventory in 2003:

  • Data base called CHIMERE


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Context

Data

Encodage

REREAU

Proposition

Conclusion

CCTV « local » codification (extract)


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Context

Data

Encodage

REREAU

Proposition

Conclusion

EN 13508-2 standard codification (2003)

Defect:

Break/collapse

Main

Aditional information

description

code

BAC

characterisation

The nature of the observation is:

Break (A)

pieces of pipe visibly displaced

-

-

Missing (B)

missing pieces of wall

-

Collapse (C)

complete loss of structural

integrity

quantification

The length of the observation in millimetres

Circumferential location

The position of the observation

Joint international conference on computing and decision making in civil and building engineering - june 14-16 2006 - Montreal


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Exemple of recodification with EN 13508-2

Joint international conference on computing and decision making in civil and building engineering - june 14-16 2006 - Montreal


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Context

Data

Encodage

REREAU

Proposition

Conclusion

RERAU methodology

  • Defects:actual physical state of the pipe

  • Dysfunctions: consequences of defects

  • Impacts: effects of the dysfunctions if vulnerability: segment and environment.

  • Direct observation (O): it is the case of CCTV inspection

  • Observation-based estimations (E/O): some time results of defects observed by CCTV

  • Estimations based on risk factors (E/R): step before CCTV inspection.


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Context

Data

Encodage

REREAU

Proposition

Conclusion

Main categories of dysfunctions


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Context

Data

Encodage

REREAU

Proposition

Conclusion

RERAU methodology: E/O T criteria valuation

Dysfunction

INFILTRATION

DYSFONCT

INF4

-

E/O

-

T

indicator

, estimated by CCTV inspection

Infiltration risk

Valuation scale

Network and sub

-

system

segment

Ø

Valuation type

Observed Dysfunction

Observed

-

based estimation of Dysfunction

Ø

Est

imations of Dysfunction based on risk factors

Unit or gravity levels

level

: 1/2/3/4

1

coding Ci of observations Oi according standard EN 13508

-

2

;

Valuation

2

translating in Ni of coded observations Ci according following

table

;

3

calcul

ation of

density

D = N / Lt

,

S

with N

=

Ni, et LT

:length of the segment (m)

;

4

comparison of D with thresholds S1, S2, S3

: level 1

if

D ? S1

;

2

if

S1 < D ? S2

; 3

S2 < D ? S3

; 4

i

S3 < D.

[

[


Slide10 l.jpg

Context

Data

Encodage

REREAU

Proposition

Conclusion

  • Available data

  • Sewers data and CCTV inspections

  • The methodolgy

  • EN 13508 standard for dysfunctions encodage

  • Using RERAU methodology: Density assess

  • Calssification of sewers in three main categories

    Good, medium and bad

    Application

  • Use mutli-criteria approach for classification: Electre-tri method

  • Use an assignment example according given by an expert

  • Partial inference: wheights and profils

    Decisions

  • Investigation plans

  • Rehabilitation programms

Chimer


Slide11 l.jpg

Context

Data

Encodage

REREAU

Proposition

Conclusion

  • Available data

  • Sewers data and CCTV inspections

    The methodolgy

  • Using RERAU methodology: Density assess

  • EN 13508 standard for dysfunctions encodage

  • Calssification of sewers in three main categories

    Good, medium and bad

  • Application

  • Use mutli-criteria approach for classification: Electre-tri method

  • Use an assignment example according given by an expert

  • Partial inference: wheights and profils

    Decisions

  • Investigation plans

  • Rehabilitation programms

Chimer

EN 13508-2

RERAU methodology

Dysfonctions asses

Sewers hierarchisation

Muti-criteria approach

Electre-Tri


Slide12 l.jpg

Context

Data

Encodage

REREAU

Proposition

Conclusion

  • Available data

  • Sewers data and CCTV inspections

  • The methodolgy

  • Using RERAU methodology: Density assess

  • EN 13508 standard for dysfunctions encodage

  • Calssification of sewers in three main categories

  • Good, medium and bad

  • Application

  • Use mutli-criteria approach for classification:

    Electre-tri method

  • Use an assignment example according given by an expert

  • Partial inference: wheights and profiles

  • Decisions

  • Investigation plans

  • Rehabilitation programms

Chimer

EN 13508-2

RERAU methodology

Dysfonctions asses

Sewers hierarchisation

Muti-criteria approach

Electre-Tri

  • Investigation plans

  • Rehabilitation programms


Slide13 l.jpg

Context

Data

Encodage

REREAU

Proposition

Conclusion

  • Asset management approach for a given segment

  • 10 dysfunctions taken into account in decision making, number of

  • criteria equal to 10.

  • 3 categories , 2 profiles

  • We consider an assignment problem of 60 sewers ,

  • 20 for each category according to expert decision

Criteria

Sewers

Categories


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Context

Data

Encodage

REREAU

Proposition

Conclusion

January 2007 – May 2007

  • encoding data available : last year - 2006

  • RERAU methodology and density calculation for each criterion

  • assignment example: expert asses, sample of 60 segments

  • determination of profiles and weights of criteria : IRIS

  • application to extended set of sewers in order to propose

    rehabilitation programs


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