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1 A multi-criteria approach for asset management of waste water networks Joint Unit Research in Water Utilities Management Cemagref-Engees 1 quai Koch.

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Presentation on theme: "1 A multi-criteria approach for asset management of waste water networks Joint Unit Research in Water Utilities Management Cemagref-Engees 1 quai Koch."— Presentation transcript:

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

2 2 Context Joint international conference on computing and decision making in civil and building engineering - june Montreal 152 sewerage utilities Context DataEncodageREREAUPropositionConclusion

3 3 Sewers inventory in 2003:  Data base called CHIMERE Data on the pipe and its environment km (4 600 km waste water) Defects noticed by CCTV inspections under « local » codification inspections defects Context DataEncodageREREAUPropositionConclusion

4 4 CCTV « local » codification (extract) Context DataData EncodageREREAUPropositionConclusion Defect gravity Horizontal fissure x Horizontal fissure, quite all around Horizontal fissure, water infiltration, quite all around Horizontal fissure, water infiltration x Horizontal fissure, visible humidity x Horizontal fissure, visible humidity, quite all around Vertical fissure x

5 5 EN standard codification (2003) Joint international conference on computing and decision making in civil and building engineering - june Montreal Defect: Break/collapse Main code Aditional information description 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 Context DataEncodageEncodage REREAUPropositionConclusion

6 6 Exemple of recodification with EN Joint international conference on computing and decision making in civil and building engineering - june Montreal

7 7 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. Context Data Encodage REREAUREREAU PropositionConclusion

8 8 Main categories of dysfunctions Main categories of dysfunctions IdentificationDysfunctions INF EXF HYD DEB DEV ENS BOU RAC EFF DSC ATC ABR Infiltration Exfiltration Decrease of hydraulic capacity Flooding Overflow Sand silting Blockage Ongoing degradation from roots intrusion Risk of collapse Destabilisation of ground-pipe system Ongoing corrosion Ongoing degradation from abrasion Context Data Encodage REREAUREREAU PropositionConclusion

9 9 RERAU methodology: E/O T criteria valuation Dysfunction INFILTRATION DYSFONCT INF4-E/O-T indicator Infiltration risk, estimated by CCTV inspection Valuation scale Network and sub-system  segment Valuation type Observed Dysfunction  Observed-based estimation of Dysfunction Estimations of Dysfunction based on risk factors Unit or gravity levels level : 1/2/3/4 Valuation 1– coding Ci of observations Oi according standard EN ; 2– translating in Ni of coded observations Ci according following table ; 3– calculation of density D = N / Lt, 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. Context Data Encodage REREAUREREAU PropositionConclusion

10 10 Available data  Sewers data and CCTV inspections The methodolgy  EN standard for dysfunctions encodage  Using RERAU methodology: Density assess  Calssification of sewers in three main categories Good, medium and bad Good, medium and bad Application 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 Decisions  Investigation plans  Rehabilitation programms Chimer Context Data EncodageREREAU PropositionProposition Conclusion

11 11 Available data  Sewers data and CCTV inspections The methodolgy  Using RERAU methodology: Density assess  EN 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 Decisions  Investigation plans  Rehabilitation programms RERAU methodology EN Dysfonctions asses Sewers hierarchisation Muti-criteria approach Electre-Tri Chimer Context Data EncodageREREAU PropositionProposition Conclusion

12 12 Available data  Sewers data and CCTV inspections The methodolgy  Using RERAU methodology: Density assess  EN 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 RERAU methodology EN Dysfonctions asses Sewers hierarchisation Muti-criteria approach Electre-Tri Investigation plans Rehabilitation programms Chimer Context Data EncodageREREAU PropositionProposition Conclusion

13 13 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 Sewers INF EXF HYD DEB DEV... ENS Category S Good S Good.... S Medium Sewers Criteria Categories Context Data EncodageREREAU PropositionProposition Conclusion

14 14 Context Data EncodageREREAUProposition ConclusionConclusion  encoding data available : last year  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 January 2007 – May 2007


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