INTERNATIONAL STANDARD ISO 24516-1 First edition 2016-11-15 Guidelines for the management of assets of water supply and wastewater systems — Part 1: Drinking water distribution networks Lignes directrices pour la gestion d’actifs des systèmes d’eaux usées et d’eau potable — Partie : Réseaux de distribution d’eau potable Reference number ISO 24516-1:2016(E) I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n © ISO 2016 ISO 24516-1:2016(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2016, Published in Switzerland All rights reserved Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n ISO 24516-1:2016(E) Contents Page Foreword v Introduction vi Scope Normative references Terms and definitions Principles aspects of the management of assets 4.1 4.2 4.3 4.4 Objectives and requirements 4.1.1 Objectives 4.1.2 Functional requirements 4.1.3 Performance requirements General aspects 4.2.1 General 4.2.2 Principal aspects — Drinking water utilities 4.2.3 Principal aspects — Drinking water systems 4.2.4 Integrating the principal aspects Risks and li fe cycle aspects 4.3.1 Risk 4.3.2 Li fe cycle 10 Structuring the process for management of assets 10 4.4.1 General 10 4.4.2 Strategies for the management of assets 11 4.4.3 Periods of planning 12 4.4.4 Strategic level activities 13 4.4.5 Tactical level activities 13 4.4.6 Operational level activities 13 Investigation 14 General 14 Purpose of investigation 14 5.2.1 General 14 Determine the scope of the investigation 14 Data collection 14 5.4.1 General 14 5.4.2 Data requirements 15 5.4.3 Inventory data 15 5.4.4 Failure data 16 5.4.5 Further condition data 16 5.5 Data registering and data assignment 18 5.5.1 Data registering 18 5.5.2 Data assignment 18 5.5.3 Geo-referencing 19 5.6 Review of existing information 19 5.7 Inventory update 19 5.8 Types o f investigation 20 5.8.1 Hydraulic investigation 20 5.8.2 Structural investigation 20 5.8.3 Operational investigation 20 5.9 Review of performance information 21 5.10 Planning of investigation 22 5.11 Performance testing 22 5.1 5.2 5.3 5.4 Assessment 22 6.1 6.2 Principles 22 Assessment o f the hydraulic performance 23 © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n iii ISO 24516-1:2016(E) 6.3 Assessment of the structural condition 6.4 Assessment of operational performance 6.5 C ompare with performance requirements 6.6 I dentificatio n o f unaccep tab le imp acts 6.7 I denti fy caus es o f p er fo rmance deficiencies Planning D evelop integrated solutions Assess solutions Prepare action p lan General C reate/up date plan 8.3 C arry o ut wo rk M onitor performance Review performance O peration M aintenance 29 1 General 0.2 S trategic p lan D o c u fo r rehab ilitatio n o f p hys ical in fras tructure (lo ng- term p lanning) General 2 Service life and failure rate development 1 0.2 D etermining the need B udgeting Tactical p lan fo r fo r rehab ilitatio n o f p hys ical in fras tructure 3 rehab ilitatio n o f p hys ical in fras tructure (mid- term p lanning) Risk-based evaluation ap proach I ndividual evaluation and p rioritizing 3 C oordination with other construction activities O perational plan m e n t a t i o n a n d e f — f i c i I mp lementation of rehabilitation measures (short-term p lanning) e n c y r e v i e w Annex A (informative) Further objectives of the management of assets of drinking water networks Annex B (informative) Examples for the assessment of service life and failure rates of pipes Annex C (informative) Examples for risk consideration in management of assets Bibliography iv 27 General Rehabilitation 1 0.3 26 Operation and maintenance 10 24 General Implementation I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n 36 38 40 42 45 ISO 24516-1:2016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f preparing International Standards is normally carried out through ISO technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso.org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) Any trade name used in this document is in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html The committee responsible for this document is Technical Committee ISO/TC 224, A list of all parts in the ISO 24516 series can be found on the ISO website Service activities relatin g to drin kin g water supply system s an d wastewater system s — Quality criteria of th e service an d perform an ce in dicators © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n v ISO 24516-1:2016(E) Introduction T h i s c u ment i s written with i n the overa l l concep t o f management o f a s s e ts wh ich i s an ac tivity a l l organi zation s under take in some manner and to some degree I t fo cuses on the detai ls of managing the phys ic a l a s s e ts at the op erationa l level rather than the organ i z ationa l (cor p orate management, s truc tural or proces s) level D rin king water uti lities are reliant on their as s ets to del iver their ser vices to the res ident p opu lations in their j uris dic tions T he as s ets (underground pip es , reser voirs , s torage tan ks , treatment plants , etc.) col le c tively form the phys ic a l i n fra s truc tu re o f the d ri n ki ng water uti l itie s a nd are the s e quence o f the acc umu lated capital inves tments and op erational exp enditures on maintenance and rehabi litation over many ye ars I n ma ny o f the s e uti l itie s , the replacement va lue o f the s e p a s t i nve s tments wi l l amou nt to ma ny m i l l ion s (even bi l l ion s) o f US dol l ars dep end i ng on the s i ze o f the com mu n ity s er ve d T he infras truc ture represents therefore a maj or so cietal inves tment in es sential ser vices contributing to public health and the protec tion of the environment In many countrie s , the s e a s s e ts have b e en identi fie d as i n fras tr uc tu re s , critic a l a nd pro gram me s are i n place to a s s u re thei r pro te c tion or thei r s u s tai nabi l ity L i ke ma ny o ther organ i z ation s havi ng as s e ts , d ri n ki ng water uti l itie s u nder ta ke pro gram me s o f ac tivitie s to manage the as s e ts to en s u re they conti nue to me e t the ne e d s o f the com mu n ity for rel i able del iver y o f d ri n ki ng water T he s e management ac tivities can b e at the s trategic, tac tical or op erational level T he ac tivities can b e p ar t of a formal ma nagement s ys tem, the re s u lt o f s p e ci fic le gi s lative re qu i rements , or s i mply the re s u lt o f due d i l igence by the s er vice op erators and managers T h i s c ument c an s er ve a s a s upp or ti ng c u ment for uti l itie s op erati ng an as s e t management s ys tem re gard le s s o f whe ther the uti l itie s ma ke u s e o f a ny management s ys tem s tandard (e g I S O 5 01) In many cou ntrie s , in fras truc ture gap, there is which a re co gn i ze d recogni zes that s u s ta i nabi l ity for various ma i ntai ne d over the ye a rs on a tru ly s u s ta i nable b as i s , i e problem, reasons , s ome ti me s the fu nd i ng and re ferre d in fras truc ture has to as not the b een i mplementation o f rehabi l itation programmes have b een p os oned, with a fo cus ins tead on shor t-term rep airs or an al lowed decrease in the level of ser vice provided T he cond ition o f water i n fra s tr uc tu re s gre atly i n fluence s the ade quac y o f the from water s er vice as p e c ts o f qua l ity, quantity, pre s s ure, s a fe ty, rel iabi l ity, envi ron menta l i mp ac t, de gre e o f tre atment and e conom ic e ffic ienc y S ys tem cond ition-b a s e d rehabi l itation appro ache s s er ve to me e t the s e requirements with a fo cus on a holis tic appro ach of condition-b ased, risk- oriented maintenance As the ins tal lation and development of water as sets mature, the op timi z ation of networks wi l l b e come ne ce s s ar y i n many place s i n order to re s p ond to cha ngi ng s o cie ta l and e conom ic cond ition s C on s e quently, ne tworks are s ubj e c t no t on ly to agei ng as wel l as we a r a nd te ar but a l s o to adap tation pro ces ses res u lting from growth, new legislative requirements , or changing cus tomer ser vice level exp e c tation s T h i s re qu i re s d ri n ki ng water uti l itie s no t on ly to fo c u s on mai ntenance a nd reh abi l itation but also to keep future requirements and developments in mind Rehabi l itation wi l l thus b ecome es sential in management of as sets , with ever more s tringent requirements on the des ign and exec ution o f rehabi l itation ( p ar tia l replacement o f s p e ci fic s e c tion s o f the enti re ne twork i s a l s o s idere d as rehabil itation) I n re cent ye ars , much e ffor t s b e en appl ie d to the whole i s s ue o f ma nagement o f as s e ts on two level s: — — Wh at are the pri nc iple s a nd s truc tu re o f a n as s e t management s ys tem? What are the go o d prac tices that can b e implemented on a technical level to as ses s the condition of the a s s e ts and help de cide when a s s e t i nter vention s (rep r, renovation or replacement) ta ke place? T h i s c ument de s c rib e s the i n formation re qu i re d and how to col le c t a nd pro ce s s rel iable i nventor y, cond ition, op erationa l a nd conte xt data ab out d ri n ki ng undergrou nd water i n fra s truc ture no tably i nclude data on for vi water fa i lu re s ys tematic mai ntenance and c a n a l s o contribute data ne e de d I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n s ys tem s C ond ition data for the T he s e data s er ve mai n ly a s a b a s i s for b ench ma rki ng ISO 45 6-1 : 01 6(E) Rel i able fa i lu re s tati s tics and the datab a s e de s crip tion o f the cond ition a re o f p ar tic u lar s ign i fic a nce establishing investigation, maintenance and rehabilitation priorities for T h i s c u ment a l s o provide s gu idance on how to defi ne a s trateg y on ma nagement o f as s e ts with regard to the overa l l p er forma nce e xp e c te d b y the d ri n ki ng water uti l ity a nd o ther s ta keholders I t includes several aspects of the operation and maintenance, including asset condition assessment and investment strategies (new assets and rehabilitation) T he appro ache s o ffere d i n th i s c u ment a re i ntende d to b e u n ivers a l ly appl ic ab le, regard le s s o f the s truc tu re o f a given water s ys tem The usual and expected goal of the effective management of assets is to provide an appropriate service l i fe wh i le fu l fi l l i ng given re qui rements i n a co s t- e ffe c tive man ner T h i s c u ment i s i ntende d to provide gu idance on the as s e ts typic a l ly owne d or op erate d by d ri n ki ng water uti l itie s (ne tworke d d ri n ki ng water s ys tem s) th at are exp e c te d to me e t c u s tomer ne e d s a nd expectations over longer (multi-generational) periods Additional information on objectives of management of assets is provided in Annex A Information on f f f f Annex B and riskbased prioritization of pipe rehabilitation in Annex C the as s e s s ment o typic a l s er vice l i e and age -b a s e d © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n lu re rate s o pip e s i s shown i n vii I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n INTERNATIONAL STANDARD ISO 24516-1:2016(E) Guidelines for the management of assets of water supply and wastewater systems — Part 1: Drinking water distribution networks Scope T h i s c ument s p e ci fie s gu idel i ne s for te ch n ic a l a s p e c ts , to ol s and go o d prac tice s of assets of drinking water networks to maintain value from existing assets for the ma nagement T h i s c ument e s no t apply to the ma nagement o f as s e ts o f water works (i nclud i ng c atch ment a nd tre atment, pu mpi ng and s torage i n the ne twork) , wh ich a re a l s o phys ic a l ly p a r t o f the d ri n ki ng water s ys tem and c an i n fluence the ma nagement o f as s e ts o f the pip e ne twork NOTE fre e The drinking water network is taken to include both pressurized and non-pressurized (i.e containing s u r face flow) co ndu its a nd acce s s or ie s s uch a s va l ve s a nd co ntro l or me ter i ng e qu ip ment NOTE The management of assets of drinking water pumping stations and storage in the network will be included in another part of the ISO 24516 series T h i s c ument fo c u s e s on the a s s e ts typic a l ly owne d or op erate d b y d ri n ki ng water uti l itie s (ne tworke d d ri n ki ng water s ys tem s) th at a re exp e c te d to me e t c u s tomer ne e d s a nd exp e c tation s over longer (mu lti- generational) periods This document includes examples for good practice approaches on the strategic, tactical and operational levels T h i s c u ment i s appl ic able to a l l typ e s and s i ze s o f orga ni z ation and/or uti l itie s op erati ng d ri n ki ng water s ys tem s , and a l l d i fferent role s/fu nc tion s for the management o f a s s e ts with i n a uti l ity (e g as s e t owner/re s p on s ible b o dy, as s e t manager/op erator, s er vice provider/op erator) NO TE D ep end i ng o n the s i z e a nd s tr uc tu re o f a n orga n i z ation , the uti l ity c a n de c ide to wh at e x tent it ap p l ie s the gu id a nce i n th i s c u ment, b ut i n a ny c a s e , the p h i lo s op hy o f th i s c u ment rem a i n s app l ic ab le to s m a l l a nd medium utilities Normative references There are no normative references in this document Terms and definitions For the pu r p o s e s o f th i s c u ment, the fol lowi ng term s and defi n ition s apply ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at http://www.iso.org/obp — IEC Electropedia: available at http://www.electropedia.org/ © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n ISO 24516-1:2016(E) 3.1 asset capital-forming go o ds used for the provis ion of the ser vice Note to entry: Assets can be tangible or intangible Examples o f tangible assets are: land, buildings, pipes, wells, tan ks , treatment plants , equ ipment, hardware E xamples of i ntangible as s e ts are: s oftware, datab as es Note to entry: Contrary to consumables, assets can be depreciated in accounting systems [SOURC E: I SO 4510 : 07, 4] 3.2 asset management processes that enable a water utility to direct, control and optimize the provision, maintenance and disposal o f in frastructure assets, including the necessary costs for specified per formances, over their li fe-cycle [SOURC E: I SO 4510 : 07, ] 3.3 asset system set of assets (3 1) that interac t or are interrelated [SOURC E: I SO 5 0 : 014, ] 3.4 asset type grouping of assets (3 1) having common charac teris tics that dis tinguish those as sets as a group or clas s Note to entry: Examples o f asset types include, but are not limited to, physical assets, in formation assets, intangible assets, critical assets, enabling assets, linear assets, in formation and communications technology (I C T ) as s ets , i n fras truc ture as s ets , move able as s ets , e tc Note to entry: Examples o f physical asset types in the water sector are pipes, valves, pumps or filters o f the same class, coating, year o f manu facture, producer or the ageing process [SOURC E: I SO 5 0 : 014, 6] 3.5 failure local inadmissible impairment o f the operability o f an asset o f a drinking water or wastewater system 3.6 failure data data describing the charac teris tics of the failure (3 ) caused at a cer tain p oint in time on a cer tain as set o f a drinking water or wastewater system 3.7 failure rate numb er of failures (3 ) p er unit Note to entry: In the case o f pipelines, expressed per kilometre per year Note to entry: For drinking water networks, in the case o f connections and valves, expressed per thousand per year 3.8 inspection identi fying the actual status o f an asset or asset system I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n ISO 24516-1:2016(E) E s tabl i s he d trend or re gre s s ion fu nc tion s may b e employe d to de s crib e the c a lc u late d age -relate d progres s ion of fai lures , to determine the ser vice l ife and to forecas t fai lure rate development I f ne ce s s ar y, e xp er ts s hou ld b e s u lte d for th i s fa i lu re s tati s tic s ana lys i s (for an e xample, s e e Figure 6) Key p ermissible failure rate increase o f annual failure rate o f, for examp le, % average failure grade increase o f annual failure rate o f, for examp le, % sp read o f failure grade worst- case scenario b est-case scenario X technical s ervice li fe, in years Y mean failure rate, in failures /km/year Figure — Example illustrating service life derivation on the basis of alternative failure rate progressions (1 % and %) In the pre s ence o f i n s u fficient data on c urrent as s e t typ e fa i lu re eva luation s , an an nua l age -relate d p ercentage i nc re a s e o f the c u rrent rate s fai lure a nd pre clud i ng s tati s tic a l rate may b e as s u me d T h i s i s an approxi mate re ference va lue a s s u me d to o cc ur i f the as s e t typ e i s no t rehabi l itate d I n s uch c as e s , orientation va lue s o f % to % a n nua l i nc re a s e i n the c u rrent fa i lu re rate s may b e u s e d to calcu late the ser vice l ife scenario T he future development of a fai lure grade can b e calcu lated with a progres s ion of %/a as the b es t- case scenario and a progres s ion of %/a as wors t- case scenario T he real scenario is in b etween the s pread of b oth fai lure grades S er vice l i fe end s and the as s e t s hou ld b e rehabi l itate d when the ac tua l the p erm i s s ible fa i lu re rate T he p erm i s s ible fai lu re rate fa i lu re rate p ermanently exce e d s for a d ri n ki ng water ne twork shou ld b e defi ne d by the d ri n ki ng water uti l ity and/or agre e d with relevant s ta keholders as a n accep te d level o f s er vice Fre quently, the ri sk as s e s s ment o f i nd ividua l mai n s s trateg y for form s the on ly b a s i s long- d i s tance and tran s m i s s ion s ys tem s O ther fac tors for de term i n i ng a rehabi l itation s uch as cond ition o f s u rrou nd i ng s oi l, tra ffic lo ad, op erati ng pre s s u re, and i n s ta l lation qua l ity shou ld a l s o b e s idere d Fu r thermore, the fai lu re rate s s hou ld b e lower th an tho s e applyi ng to d i s tribution ne tworks I n pri nciple, however, e ach pip el i ne s ys tem s hou ld b e add re s s e d s ep a rately with rega rd to the vu l nerabi l ity aga i n s t as any fai lu re fai lu re c an entai l la rge - s c a le water s upply i nterr up tion s re s u lti ng i n s ub s tantia l i mp ac t (e g haz ard s to huma n s and prop er ty) B y contra s t, re dundant long- d i s tance a nd tru n k ma i n s no t p o s e any i ncre as e d ri s ks and may b e tre ate d l i ke ma i n s with i n the ne twork 32 I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n ISO 24516-1:2016(E) If the available data not permit a failure forecast, the pipe deterioration of the drinking water network may, alternatively, be assessed on the basis o f the estimated residual service li fe; see also Annex B 10.2.3 Determining the need for rehabilitation of physical infrastructure 10.2.3.1 General The annual rehabilitation need depends largely on the service li fe expected for the individual asset types The following methods may be used to determine the required rehabilitation rates on the basis o f the data available (volume, quality, currentness) Results become more reliable the greater the body o f data available and the greater the level o f detail I f a correspondingly detailed data collection and analysis are available, the pre ferred method should be Method 3, in particular with a view to enhancing economic e fficiency and planning sa fety (see Re ference [17]) 10.2.3.2 Method 1: Direct asset type-specific derivation from service li fe The reciprocal of the expected service lives (and/or the residual service lives if little or no rehabilitation measures have been taken so far) o f the asset types concerned may be used as a first approximation for determining the required annual rehabilitation rate This is true particularly for drinking water networks that have grown homogenously over a long period o f time, and for which no reliable data are available on age-related length distributions within the asset types An expected asset type service li fe o f 50 years or 100 years, for example, entails strategic rehabilitation rates o f % or % per annum, respectively Taking into account all asset types within a drinking water network, this is an easy way to derive as a first approximation, the required long-term rehabilitation rate for the entire drinking water network For asset type-based technical service li fe experience, see example in Figure B.1 10.2.3.3 Method 2: Derivation from technical service lives and age-related existing asset lengths I f data on existing assets are available with re ference to age and asset types within a drinking water network, their rehabilitation needs over time can be determined as a first approximation As a first step, the service life (see 10.2.2 ) of the asset type concerned is assumed to apply to all individual assets Based on the individual year o f construction, the respective rehabilitation time frames can be estimated from the estimated end o f their technical li fe Taking into account all asset types within the drinking water network, the rehabilitation needs applicable to the entire drinking water network over the long term are thus determined analogously to Method While the rehabilitation rate can level out because the service lives assumed for the individual asset types can possibly overlap, the resulting overall rehabilitation rate generally shows volatility on a yearto-year basis It is there fore recommended to average the resulting rehabilitation rates over years or 10 years in order to obtain stable values, always observing the asset type to which they pertain 10.2.3.4 Method 3: Derivation from mathematical distribution functions In real li fe, it is not only the service li fe o f a homogenous asset type that cannot be determined with absolute certainty Actual operating service lives o f individual assets within an asset type also vary within certain boundaries, depending on the factors a ffecting the system’s condition This fact may be taken into account as well when devising rehabilitation strategies By employing mathematical distribution functions (e.g Gaussian, Weibull, Herz distribution), the probable point of transition into provides a more meaningful picture of required, long-term annual rehabilitation rates the projected poor condition (i.e the end o f the service li fe) can be calculated This method ultimately Commercially available so ftware products and the corresponding necessary data are available and may be employed to calculate service li fe margins and derive from this basis one or more o f the above- © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n 33 ISO 24516-1:2016(E) mentioned probability distributions This can help utilities to determine rehabilitation rates (see, as an example for a pipe type-dependent grade o f failure rate, Figure B.2) 10.2.4 Budgeting The rehabilitation budget required to implement a rehabilitation strategy is generally determined by the product of the annual rehabilitation rates and the respective asset lengths and numbers and the specific cost estimates Cost estimates should be based on utility-specific, long-term empirical data, as well as on any planned changes in pipe materials and systems The results o f possible strategic network optimization activities should likewise be included in the rehabilitation budget calculation As far as mains and in particular trunk and long-distance mains are concerned, reliable budgeting generally always pre-supposes individual pipe examinations Since a rehabilitation budget calculated in accordance with the method described above only covers the condition-based rehabilitation o f a drinking water network, expenditures on third-party induced replacement (in the absence of an urgent need for rehabilitation) should be added to the rehabilitation strategy budget Such additions should be in the form o f an average basic amount based on long-term empirical data, unless covered by a separate budget Any activities carried out in the course o f urgent network optimization procedures, such as remedying current functional weaknesses in the drinking water network, should be reflected by short-term rehabilitation budget increases 10.3 Tactical plan for rehabilitation of physical infrastructure (mid-term planning) 10.3.1 Risk-based evaluation approach Reaching the rehabilitation objectives presupposes knowledge of the risks involved With the exception o f quality problems (e.g turbidity), which can have many di fferent causes, the risk emanating from the drinking water network is generally derived from the probability o f pipe failure (and indirectly also from water losses) and the respective extent o f the failure resulting in hazards to humans, third-party assets and the environment In addition, failures in the supply quality, direct added costs and possibly the resultant negative public perception o f the failure and the image o f the utility should be taken into account The probability and the extent to which drinking water quality is a ffected can be derived from customer complaints, operating experience, measured values and pipe network simulations As far as the rehabilitation strategy is concerned, the aspect o f risk can only be considered to a limited extent The only feature that can be generally analysed and predicted in the technical evaluation o f the rehabilitation strategy is the development o f the asset type-related failure probability I f water losses or turbidity can be clearly attributed to individual pipe types (asset types) and not to individual line sections, these aspects, too, can be taken into account in the rehabilitation strategy In rehabilitation planning and rehabilitation measures, all influencing risk factors can be evaluated by re ference to the location of the individual assets All requirements should be completely fulfilled and cannot be o ffset one against another Low failure rates not necessarily imply a high supply quality even when water losses are high This situation means that there are pipe failures which have not yet been discovered probably due to un favourable soil conditions Although increased inspection activities to reduce the water losses can help as a first step to detect and to reduce the water losses locally, the only way in the long run o f keeping network failure rates, water losses and thus also the risks permanently low is a well-targeted rehabilitation strategy for the pipe network For further information on a risk-based evaluation approach, see Annex C The tactical rehabilitation plan pursues the objective of implementing in the medium term, i.e within two years to five years, the rehabilitation rates determined by the rehabilitation strategy for the individual asset types The rehabilitation measures required for the task should be identified and prioritized 34 I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n ISO 24516-1:2016(E) The prioritization criterion should be the risk emanating from hazards affecting a pipe section This risk results from the probability o f occurrence and the extent o f loss or failure The utility should define utility-specific evaluation criteria and an evaluation approach adequately reflecting the selected criteria and producing evaluation results for each pipe section Risk assessment evaluation criteria can be subdivided into the following groups: a) The probability o f failure occurrence can be deduced from 1) the failure rate development in an individual section, 2) the failure rate development in the asset type (failure and/or empirical data), 3) other pipe condition data (e.g corrosion, connection type, pipe coating), 4) ambient data (e.g bedding, soil corrosiveness, stray currents, tra ffic load, overbuilding), and 5) knowledge about fluctuating pressure changes b) The probability o f occurrence o f quality impairments can be deduced from 1) customer complaints, 2) operational experience, 3) measured values, and 4) calculations c) The extent of loss or failure can be assessed with a view to 1) cost, 2) quality o f supply (pressure, quantity, quality, availability), 3) hazards to persons and other assets (type o f pipeline, location, distance from others’ assets and tra ffic routes, dimension), and 4) utility’s image/public perception Network evaluation results serve to assess the risk for each pipe section on the basis o f pre-defined criteria The evaluation results for the entire network or for individual network sections determine the rehabilitation priority ranking o f the pipe sections concerned Risk can be expressed by a variety o f units Figure illustrates the general process for network evaluation Figure — Network evaluation process 10.3.2 Individual evaluation and prioritizing An evaluation standard should be defined for the relevant criteria, e.g in the form o f points scored, with negative evaluations scoring more points Each criterion should be applied to each pipe section, its final evaluation being attained by adding and/or multiplying the individual evaluation results As this step constitutes the most crucial procedure at this stage of the process, it should be prepared and coordinated with due care The mathematical combination of the individual evaluations should correctly reflect the weighting o f the criteria against each other Sorting the evaluation results then yields the priority ranking o f the rehabilitation measures planned for the medium term © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n 35 ISO 24516-1:2016(E) When selecting evaluation criteria, care should be taken to ensure that information about each criterion is available for each pipe section or else the evaluation results can be inappropriately biased The list of priorities should provide the following information about the individual pipe sections as a minimum requirement: — unambiguous pipeline identification (technical data, geography); — length o f section; — quantitative evaluation (e.g how many points have been scored) The list of priorities should be compared to the pre-determined strategic rehabilitation objectives (e.g attaining a certain level of rehabilitation) The list of priorities should be processed in accordance with the rehabilitation strategy Any deviations from the list o f priorities in the rehabilitation strategy should be evaluated and examined for their relevance to impacts on the rehabilitation strategy The prioritization should be made by using a risk matrix with the axis, e.g failure extent versus failure probability system (see Figure C.1), or a risk scoring classification system (class A, B, C) 10.3.3 Coordination with other construction activities Coordination with activities carried out by other industries or contractors (e.g gas, wastewater, telecommunication, rehabilitation or reconstruction o f roads) can entail a change in priority ranking, which, in turn, can make the utility’s construction work more economically e fficient 10.4 Operational plan planning) — Implementation of rehabilitation measures (short-term The rehabilitation methods should be designed and implemented on the basis of the rehabilitation strategy and rehabilitation plan, always taking into account prevailing local conditions Alternative construction measures comparable from a supply technology point o f view should be considered when planning the construction measures It can make sense to simultaneously rehabilitate adjacent pipe sections o f roughly the same priority ranking so as to achieve economies in the rehabilitation programme (e.g having larger units of project and appropriate construction equipment on-site for longer periods without incurring repeated relocation costs) Asset management and annual construction/rehabilitation measures are also constrained by the road programme implementation or the impact o f the development projects These projects can sometimes significantly impact the lists o f sections to be rehabilitated, by anticipating mains not already ageing or by de ferring the rehabilitation in time Dimensions, rehabilitation technology (open or trenchless installation technologies, renovation, predictable repair work, cleaning) and the rehabilitation materials should be defined for the individual pipeline construction measures This should also include quality assurance o f materials and installation, as well as requirements for the executing contractors 1 D o c u m e n t a t i o n a n d e f f i c i e n c y r e v i e w All major results and decisions should be documented so as to be able to understand the individual process steps, from the original strategic approach to the final execution o f the work Care should be taken in this context to include previous experience with such measures and apply it to planning future work The documentation should be sa fely filed, publicized and made accessible E fficiency reviews should be carried out at regular intervals including all persons involved in the respective processes in order to be able to adapt the rehabilitation strategy and plan To this end, the following questions should be addressed: — Have the rehabilitation objectives been reached? 36 I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n ISO 45 6-1 : 01 6(E) — H ave the budge t s trai nts b e en ob s er ve d? — Were the reh abi l itation te ch nique s and materi a l s ade quate or were there b e tter s olution s? — I s there a ne e d to mo d i fy any eva luation c riteria and/or s ta nda rd s? — Wa s the co s t p er s er vice or c apita l s p ent targe t ach ieve d? — Were the i n fra s truc tu re a s s e t cond ition i nd ic ators acc u rate a nd u s e fu l? — D o the i nd ic ators ne e d to b e adj u s te d? — Were the rehabilitation works carried out without negative impact on the network users or the envi ron ment? In all cases, answered i f the a s s e s s ment i s ne gative, then the que s tion “Why no t? ”, i f app l ic able, s hou ld be T he e ffic ienc y review s hou ld b e c umente d cle a rly and made acce s s ible to the de c i s ion ma kers T he reh abi l itation s trateg y i n place shou ld b e reviewe d ever y five ye ars (or le s s) and mo d i fie d, i f ne ce s s ar y The current rehabilitation plan should be reviewed on the basis of the performance monitoring reports, and no le s s fre quently tha n once p er ye ar, a nd mo d i fie d i f ne ce s s ar y © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n 37 ISO 24516-1:2016(E) Annex A (informative) Further objectives of the management of assets of drinking water networks Reasons for the management of assets of drinking water networks are the following: — d ri n ki ng water ne tworks a re exp o s e d to ri s k- ca rr yi n g i nterna l a nd ex terna l i nter ference s i mp ac ti ng hygiene and s e c u rity o f s upply; — water s upply s ys tem s are de s igne d to have long s er vice l ive s; — the ab s ence o f mai ntena nce c a n endanger the conti nue d e xi s tence o f the d ri n ki ng water uti l ity b y c au s i ng grave deviation s from water qua l ity a nd s e c urity o f s upp ly s tandard s , re s u lti ng i n s eriou s damage to th i rd p ar tie s; — the u s er h as a right to dema nd s upply o f s a fe d ri n ki ng water; — i nterr up tion s o f s upply s hou ld b e kep t to a m i n i mum The management of assets of drinking water networks should take into account the following operational and maintenance objectives: — m i n i m i z i ng envi ron menta l i mp rment; — c au s i ng no de tri menta l i mp ac t to publ ic he a lth; — avoida nce o f water qua l ity i mp a i rments; — re duc i ng water lo s s e s or ke epi ng them low; — s tabi l i z i ng the pre s s u re level; — ke epi ng s upply i nterrup tion s , e s p e c i a l ly tho s e c au s e d b y pip e fai lu re (nu mb er and du ration p er u s er) , to a m i n i mu m; fai lu re s a nd de fe c ts with i n a re a s onable p erio d o f ti me; — corre c ti ng — op ti m i z i ng the s er vice l i fe o f e xi s ti ng s ys tem s , wh i le s i mu ltane ou sly mai nta i n i ng s upply qua l ity; — mai nta i n i ng and i mprovi ng u s er s ati s fac tion; — op ti m i z i ng mai ntenance co s ts , wh i le mai ntai n i ng the re qui re d level o f s er vice; — s er vi ng the exi s ti ng s tr uc tu re and s a feguard i ng o f the qua l ity o f the d ri n ki ng water ne twork; — en s u ri ng the envi ron menta l comp atibi l ity o f a l l me a s ure s and ac tivitie s T he overa l l obj e c tive o f the ma nagement o f a s s e ts s hou ld b e to en s ure that the d ri n ki ng water uti l ity compl ie s with its s upply mandate wh i le a l s o mai nta i n i ng a s table e conom ic p o s ition The provisions set forth in this guideline are intended to help attain these operation and maintenance obj e c tive s and prevent a ny negative s e quence s c au s e d b y p o tenti a l h a z a rd s to the s e c u rity o f s upply (qua ntity, pre s s u re a nd qua l ity) H a z ard s c a n b e c au s e d b y, — i ncorre c t d i men s ion i ng o f pip e s; — i nappropriate choice o f materi a l s and comp onents; 38 I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n for e xa mple: ISO 45 6-1 : 01 6(E) fau lty — u n s u itab le or de s ign or s tr uc tion me tho d; — i ncorre c t rep r or ma i ntenance me a s ure s h avi ng contac t with d ri n ki ng water; — p o or com m i s s ion i ng/de com m i s s ion i ng ac tivitie s; — op erati ng with critic a l flow cond ition s (e g flu s h i ng) ; — p o or s ys tem d i s i n fe c tion or s e condar y d i s i n fe c tion i n the pip el i ne ne twork; — i nade quate rehabi l itation prac tice s; — u n s a fe d i s tribution concep ts; — fu nc tiona l fau lts — u naccep table water pre s s u re s; — p o or s ys tem op erationa l ma nagement and/or s e c urity control s; — i mp rment c au s e d b y envi ronmenta l — p o or th i rd-p ar ty s truc tion work; — i n s u ffic ient nu mb ers or qua l i fic ation o f s ta ff; — i nade quate plant management; — s tagnant water; — p o or s torage o f comp onents; — i n fi ltration or — h igh water lo s s e s; and fa i lu re fe e d i ng o f s ys tem s a nd comp onents; fac tors; o f non-p o table water; — frequent pipe failures The hazards listed above can form the basis for further risk assessment © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n 39 ISO 24516-1:2016(E) Annex B (informative) Examples for the assessment of service life and failure rates of pipes An example for the assessment o f minimum and maximum service lives o f pipes by pipes type based on exp erience is shown in Figure B Key AC PVC PE Gen/PE 0 PE 63 /PE Steel after Steel until D I with PE , ZN o r cement coating D I without co ating C l after 10 C l until X year Y p ipe material Figure B.1 — Example for the assessment of service life of different pipe types shows as an example o f the predicted failure rate development for di fferent pipe types (type o f material, coating, jointing, corrosion protection) based on the Kaplan-Meier procedure and approximated by a Weibull function as basis for failure rate prognosis Figure B [1 ] 40 I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n ISO 24516-1:2016(E) Key X Y CI [cast iron (in sand forms)] (until 1930) ST1 (until 1980) AC PE63 (until 1980) s ervice li fe, in years failure rate, in failures /km/year Figure B.2 — Example for predicted failure rate development of different pipe types © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n 41 ISO 45 6-1 : 01 6(E) Annex C (informative) Examples for risk consideration in management of assets C.1 Risk-based assessment for rehabilitation of pipes [1 ] T he prob abi l ity o f pip el i ne -accident o cc u rrence may b e s e t b y collected data: 1) fol lowi ng me tho d s accord i ng to the Perio d o f ye a rs i n u s e To ana lys e the pip e typ e s with h igh p o s s ibi l ity o f fai lu re b y the u s age ye a rs I n the fi rs t s tep, age s o f as s e ts c an b e u s e d a s the i nd ic ator o f l i kel i ho o d o f pip e — : E lap s e d ye ars o f or more; — 4: E l ap s e d ye a rs o f or more to le s s than ; — : E lap s e d ye ars o f or more to le s s tha n ; — : E lap s e d ye ars o f 10 or more to le s s tha n ; — : E lap s e d ye ars o f le s s th an 10 fai lu re For exa mple, 2) Operation and maintenance information To ana lys e the fac i l itie s and/or are as with h igh p o s s ibi l ity o f fa i lu re b y i nter viewi ng p ers on nel with operation and maintenance experience and consulting the operation and maintenance data (data concern i ng faci l ity cond ition s ob tai ne d b y i n s p e c tion and rep a i r, e tc , s u lt data concern i ng u s ers ’ complai nts ab out colou re d water, e tc ) likelihood cl as s i fie d b y are a a nd faci l ity that c an b e u s e d to e s ti mate For example, likelihood of failure should be estimated based on characteristics as follows: — pip e u nder p e c u l i ar lo c a l cond ition s and envi ron ment, e tc ; — pip e op erate d with p e c u l i ar pre s s u re; — areas in which there were complaints and/or unusual cases (e.g surroundings of a site of a road col lap s e, low cover, advers e l ayi ng cond ition s , compl nts) ; — pipe at a location where there is a special feature in the environment of its surrounding area (e.g an are a i n wh ich la nd s ub s idence i s l i kely to o cc ur, a n a re a with an envi ron ment exp erienc i ng h igh grou ndwater s a l i n ity s uch as a co as ta l a re a) ; — pipe conditions, e.g material, diameter, joints, corrosion protection, lining 3) Functioning rate estimation curve To na rrow down the fac i l itie s with the h ighe s t p o s s ibi l ity o f fa i lu re b y the fu nc tioni ng c ur ve, the acc u mu l ate d data “ fu nc tion i ng rate” i s u s e d, wh ich i s the ratio o f prop erly to the mains as a whole (see 10.2.2 and Annex B) “Fu nc tion i ng rate” i s the ratio o f prop erly Annex B) 42 I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n func tion i ng rate e s ti mation fu nc tioni ng mai n s to the mai n s a s a whole (s e e mai n s 10.2.2 and ISO 45 6-1 : 01 6(E) C.2 Example for risk-based prioritization for rehabilitation of pipes Example for risk-oriented rehabilitation and a condition-based prioritization of pipes: The extent of damage can result from a pipe failure under the aspects of — hazards to humans and structures, — supply quality (pressure, quantity, quality and availability), — repair/follow-up costs and may also be taken into consideration besides the failure probability Turbidity e ffects may be taken into consideration based on frequency and intensity and independent o f the pipe failure risk A basic evaluation of risk-oriented rehabilitation can be carried out using Formula (C.1): ) ( ( ) ( = q F × + s + s + s + s × fH + fQ + fC + q T × fT r ) (C.1) where risk; r q F (type o f pipe-related) failure rate; q T rate o f turbidity; s4 line-specific evaluation factors for failure probability; H f Q f C f T f s f f ailure extent regarding supply quality; ailure extent regarding costs; f f C.3 ailure extent regarding personal and environmental hazards; ailure extent regarding turbidity Example for a condition-based prioritization for the rehabilitation of pipes The following example for a risk matrix shows all single rehabilitation measures related to extent of failure versus failure probability Measures on the upper line in Figure C.1 have the same risk Measures right above the upper line should be in focus of rehabilitation © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n 43 ISO 24516-1:2016(E) Key X failure Y failure extent (risk points) p ro b ab ility, in failures /km/year Figure C.1 — Risk matrix T he priority o f me a s u re s i s o f cou rs e no t the on ly s ele c tion criterion I t merely s er ve s a s a s upp or t in s ele c ti ng the me a s u re s T he p ers on in cha rge s hou ld s ider th i s b e fore any lo c a l ly avai lable information (e.g coordination of the measures with other contractors, combination of measures) in his fi na l de ci s ion concern i ng the i mplementation o f the me a s ure s 44 I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n ISO 45 6-1 : 01 6(E) Bibliography [1] [2] [3] ISO 9000:20051) , Quality management systems —Fundamentals and vocabulary ISO 19440:2007, Enterprise integration — Constructs for enterprise modelling ISO 24510:2007, Activities relating to drinking water and wastewater services — Guidelines for the [4] ISO 24512, Activities relating to drinking water and wastewater services — Guidelines for the [5] [6] [7] [8] [9] ISO 31000, Risk management — Principles and guidelines IEC 31010, Risk management — Risk assessment techniques ISO 55000:2014, Asset management — Overview, principles and terminology ISO 55001, Asset management — Management systems — Requirements ISO 55002, Asset management — Management systems — Guidelines for assessment and for the improvement of the service to users management of drinking water utilities and for the assessment of drinking water services ISO 55001 the application of [10] EN 15898:2011, Conservation of cultural property — Main general terms and definitions [11] EN 15975-2, Security of drinking water supply — Guidelines for risk and crisis management — Part 2: Risk management [12] EN 15978:2011, Sustainability of construction works — Assessment of environmental performance of buildings — Calculation method [13] [14] [15] [16] EN 16323:2014, Glossary of wastewater engineering terms EN 752:2015, Drain and sewer systems outside buildings DVGW-W403 (M), April 2010, Decision support for the rehabilitation for water distribution systems DVGW-W400, Part (A), September 2006, Technische Regeln Wasserverteilungsanlagen (TRWV) — Teil 3: Betrieb und Instandhaltung [17] DVGW-W402 (A), September 2010, Network and damage statistics — Registering and evaluating data for the maintenance of water pipe networks [1 ] K E L., & M eier P (1958), Nonparametric estimation from incomplete observations B Rehabilitation of Water Distribution Facilities — The Holistic Approach of the German aplan [19] H eyen DVGW Standards; International Water Association 4th Leading Edge Conference on Strategic Asset Management September 27-30, 2011, Mülheim an der Ruhr, Germany 1) C ancelled and rep laced by I S O 0 : © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n 45 ISO 45 6-1 : 01 6(E) ICS 13.060.01; 13.060.20 Price based on 45 pages © ISO 2016 – All rights reserved I n tern ati o n al Org an i z ati o n fo r S tan d ard i z ati o n