A multi-criteria approach for asset management of waste water - - PowerPoint PPT Presentation

1

A multi-criteria approach for asset management

• f waste water networks

Joint Unit Research in Water Utilities Managem ent Cem agref-Engees 1 quai Koch 670 70 Strasbourg, France.

D2-Decision Deck project Workshop, March 8-9, 2007 , University of Luxem bourg.

Am ir NAFI, Caty WEREY

2

Context Context

Joint international conference on com puting and decision m aking in civil and building engineering - june 1 4 -1 6 2 0 0 6 - Montreal

152 sewerage utilities

Context Context Data Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion

3

Sewers inventory in 2003: Data base called CHIMERE

Data on the pipe and its environm ent 5 1 0 0 km ( 4 6 0 0 km w aste w ater) Defects noticed by CCTV inspections

under « local » codification

3 2 2 3 2 inspections 8 9 3 1 1 defects

Context Context Data Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion

4

CCTV CCTV « « local local » » codification (extract) codification (extract)

Context Context Data Data Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion

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 Defect gravity 1 2 3 4 5

5

EN 13508 EN 13508-

• 2 standard codification (2003)

2 standard codification (2003)

Joint international conference on com puting and decision m aking in civil and building engineering - june 1 4 -1 6 2 0 0 6 - 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 Context Data Data Encodage Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion

6

RERAU methodology RERAU methodology

q Defects: actual physical state of the pipe q Dysfunctions: consequences of defects q I m pacts: effects of the dysfunctions if vulnerability: segment and environment. q Direct observation ( O) : it is the case of CCTV inspection q Observation-based estim ations ( E/ O) : some time results of defects

• bserved by CCTV

q Estim ations based on risk factors ( E/ R) : step before CCTV inspection.

Context Context Data Data Encodage Encodage REREAU REREAU REREAU Proposition Proposition Conclusion Conclusion

7

Main categories of dysfunctions Main categories of dysfunctions

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 INF EXF HYD DEB DEV ENS BOU RAC EFF DSC ATC ABR

Dysfunctions I dentification

Context Context Data Data Encodage Encodage REREAU REREAU REREAU Proposition Proposition Conclusion Conclusion

8

RERAU methodology: E/O T criteria valuation RERAU methodology: E/O T criteria valuation

Dysfunction I NFI LTRATI ON

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 13508

• 2 ;

2 – translating in Ni of coded observations Ci according following table ; 3 – calculation of density D = N / Lt , with N= ΣNi, et LT:length of the segment (m); 4 – comparison of D with thresholds S1, S2, S3 : level 1if D ? S1 ; 2if S1 < D ? S2 ; 3[ S2 < D ? S3 ; 4[ i S3 < D.

Context Context Data Data Encodage Encodage REREAU REREAU REREAU Proposition Proposition Conclusion Conclusion

9

Available data q Sewers data and CCTV inspections The The m ethodolgy m ethodolgy q q EN 13508 standard for dysfunctions EN 13508 standard for dysfunctions encodage encodage q q Using RERAU methodology: Density assess Using RERAU methodology: Density assess q q Calssification of sewers in three main categories Calssification of sewers in three main categories Good, medium and bad Good, medium and bad Application Application q q Use Use mutli mutli-

• criteria approach for classification:

criteria approach for classification: Electre Electre-

• tri method

tri method q q Use an assignment example according given by an expert Use an assignment example according given by an expert q q Partial inference: Partial inference: wheights wheights and and profils profils Decisions Decisions q q Investigation plans Investigation plans q q Rehabilitation Rehabilitation programms programms

Chim er

Context Context Data Data Encodage Encodage REREAU REREAU Proposition Proposition Proposition Conclusion Conclusion

10 Available data q Sewers data and CCTV inspections

The m ethodology q Using RERAU methodology: Density assess q EN 13508 standard for dysfunctions codification q Calssification of sewers in three main categories Good, medium and bad Application Application q q Use Use mutli mutli-

• criteria approach for classification:

criteria approach for classification: Electre Electre-

• tri method

tri method q q Use an assignment example according given by an expert Use an assignment example according given by an expert q q Partial inference: weights and profiles Partial inference: weights and profiles Decisions Decisions q q Investigation plans Investigation plans q q Rehabilitation Rehabilitation programms programms

RERAU m ethodology EN 1 3 5 0 8 -2 Dysfonctions asses Sew ers hierarchisation Muti-criteria approach Electre-Tri Chim er

Context Context Data Data Encodage Encodage REREAU REREAU Proposition Proposition Proposition Conclusion Conclusion

11

Available data q Sewers data and CCTV inspections The m ethodology q Using RERAU methodology: Density assess q EN 13508 standard for dysfunctions codification q Calssification of sewers in three main categories Good, medium and bad Application q Use mutli-criteria approach for classification: Electre-tri method q Use an assignment example according given by an expert q Partial inference: weights and profiles Decisions q Investigation plans q Rehabilitation programms

RERAU m ethodology EN 1 3 5 0 8 -2 Dysfonctions asses Sew ers hierarchisation Muti-criteria approach Electre-Tri

• I nvestigation plans
• Rehabilitation program s

Chim er

Context Context Data Data Encodage Encodage REREAU REREAU Proposition Proposition Proposition Conclusion Conclusion

12

Asset management approach for a given segment q 10 dysfunctions taken into account in decision making, number of criteria equal to 10. q 3 categories , 2 profiles q We consider an assignment problem of 60 sewers , 20 for each category according to expert decision

S1 120 20 30 40 50 60 Good S2 120 20 30 40 50 60 Good . . . . . . . . . . . . . . . . S60 120 20 30 40 50 60 Medium Sewers I NF EXF HYD DEB DEV ... ENS Category

Sew ers Criteria Categories

Context Context Data Data Encodage Encodage REREAU REREAU Proposition Proposition Proposition Conclusion Conclusion

13 Context Context Data Data codification codification REREAU REREAU Proposition Proposition Conclusion Conclusion Conclusion

q encoding data available : last year - 2006 q RERAU methodology and density calculation for each criterion q assignment example: expert asses, sample of 60 segments q determination of profiles and weights of criteria : IRIS q application to extended set of sewers in order to propose rehabilitation programs q implementation of the method in sewer utility January 2 0 0 7 – May 2 0 07