Owners of infrastructure assets have responsibility for the management of a diverse portfolio of civil engineering assets. These assets make up the foundations of modern society and are arguably pivotal in the economic growth and wellbeing of a nation. It is of no surprise therefore, that asset management business practises have risen in popularity as the UK’s infrastructure asset base continues to grow and inevitably ages with time. In the context of water and waste water infrastructure assets, which communities rely upon for health, economy and environmental sustainability, it is widely acknowledged that these assets have historically suffered from underinvestment. Whilst funding shortfalls have been evidenced historically, through the inadequacy of infrastructure to meet the needs and challenges of the past, it is of great concern that infrastructure expenditure is reducing in real terms as a result of the global financial crisis. This is leading to a widening funding gap between the available and the required finances for infrastructure investment which is further compounded by natural phenomena and human behaviours, i.e., climate change, population growth and urbanisation. To further intensify the problem, asset planning and management in the water industry is considered a complex and challenging discipline because of high interdependencies and the vast quantity of assets themselves. In acknowledgement of this global position, this thesis seeks to address some of the key challenges faced by utility companies in the adoption of asset management best practice across water and waste water assets, namely: • Operational decision making - the efficient and effective specification of least-cost rehabilitation programmes from condition information that ensure behavioural alignment with an organisations strategic objectives. • Tactical decision making - achieving risk based asset level inspection prioritisation that considers serviceability performance, for two particularly challenging asset groups: i.) High value - low volume assets and ii). Low value - high volume buried infrastructure. • Strategic decision making - identifying optimal long-term investment plans and asset management policies for assets that have previously not benefited from such technological advancements. To improve upon operational decision making, the author capitalises on the availability of condition inspection information for buried sewerage infrastructure by applying advanced optimisation techniques to help form an environment where the decision makers is presented with an array of optimal rehabilitation solutions. The trade-off curve that is presented uniquely evaluates solutions for the benefits they offer in-terms of: condition improvement, cost and operational performance. A financially favourable comparison (up to 45% saving) is drawn between the optimisation results which are automatically generated by the model and those that have been developed manually by experienced engineers in a ‘real world’ case study. However, it could be argued that the greatest benefit arises from the trade curve of feasible solutions which are presented to the decision maker across a range of investment levels. In recognition that tactical and strategic decision making have been the focus of a substantial amount of research for commonly found infrastructure assets, i.e., public sewers and water mains, a focus has been placed on improving upon and adopting best practise across infrastructure assets which have not previously benefited from the technological developments across these decision making levels. Firstly, a methodology for translating standardised condition inspection information into more meaningful reliability scores, to support risk based planning and decision making, is presented for service reservoirs. A service reservoir can be regarded as high value- low volume infrastructure asset and would typically have its condition evaluated between 1 (poor) to 5 (good). A case study demonstrates how this new reliability scoring mechanism has been successfully applied during a typical structural condition survey. The output from this process is a fully document reliability assessment for each component of the service reservoir. The output can be aggregated to provide an overall reliability assessment for the structure and/or used to target specific remedial works to troublesome components. Secondly, two methodologies are presented which address the fact that high volume – low value infrastructure assets across both the water distribution and wastewater collection networks, are typically less well understood and often sub-optimally managed in comparison to more critical or higher value assets. 1. A methodology has been developed to help UK water companies overcome the recent legislative changes associated with Section105A of the Water Act; which has transferred ownership of the private sewer network to UK water companies. The new methodology which has been developed, has allowed one of the UK’s water and sewerage companies to initiate a proactive asset management programme with the aim of addressing the deteriorating condition of these assets whilst also tackling their associated serviceability performance. Initially, a number of GIS tools are used to provide an estimate of the likely extent of the transferred network before a well-established public sewer deterioration model is used to predict the condition and operational performance of these S105A assets over time. 2. A novel deterioration modelling framework is developed by coupling the latest geospatial technologies with statistical deterioration modelling techniques. The modelling framework is specifically applied to small diameter water distribution assets (25-50mm diameter), known as communication pipes, which connect individual properties to the water distribution mains. Reliability curves are developed from failure data provided by two UK based Water Companies that have captured specific communication pipe failure records since 2001. The deterioration modelling curves and supporting data are compared and contrasted to demonstrate the robustness of this modelling approach, which is shown to be capable of modelling failure rates to a high degree of accuracy. This was validated by comparing the predicted number of failures against three years of failure data not used during the model building process. The yearly failure counts were predicted to within +/-5% accuracy and the overall cumulative modelled failure count at the end of 2014 was predicted within 1%. To conclude, the successful deterioration modelling tools for communication pipes are explored further, via the development of a strategic whole life cost optimisation framework for these assets. The outputs from the previous geospatial mapping tool are used alongside the calibrated Weibull deterioration curves to drive a whole life cost and performance analysis. Against this improved understanding of whole life costs, an optimisation algorithm is used to evaluate the trade-off between whole life costs (totex) and the prevention of future asset failures (serviceability). The model successfully identifies optimised investment policies according to the decision maker’s priorities which is evidenced in a case study that shows outperformance against existing maintenance policies for these assets. Financial savings in the region of £8.5M, or the prevention of 1,320 asset failures, were shown to be possible over a 25 years planning horizon in the case study. For the avoidance of confusion, the term ‘integrated’ is considered from the perspective of the three decision making levels associated with the management of an asset, namely: strategic, tactical and operational decision making. Therefore, data quality improvements and the management of information transactions between decisional levels are inherently considered within all of the methodologies developed in this thesis.

Syftet med denna studie har varit att undersöka om koloniträdgårdar läcker näringsämnen till Drevviken i Stockholms län. Underlaget till studien kommer från en kvalitativ intervju med tre representanter från Miljöförvaltningen i Stockholms stad samt litteraturstudier. Resultaten visar att det föreligger problem med att kolonister använder sig av egna avloppslösningar vilket inte är tillåtet enligt arrendeavtalet. Stockholm stad står fast vid att indraget vatten fortsättningsvis inte ska få förekomma trots att ansträngningar gjorts från Skarpnäcks stadsdelsnämnds sida med att utforma bra avloppslösningar för kolonistugor. Dessa avloppslösningar arbetades fram under två år genom projektet Möjlighet att anordna avlopp inom delar av Listuddens koloniområde. Den enda åtgärd som idag tillämpas är att arrendeavtalet ska följas eftersom problemet med näringsläckage från kolonistugor då inte längre skulle vara ett problem. Dock görs inga ansträngningar att motverka problemet. Inga inventeringar av avlopp vid koloniträdgårdar görs idag och ingen information går heller ut till kolonister om de regler som gäller. I de åtgärdsprogram för Drevviken som ligger till grund för studien, har endast förslag tagits fram att inventera koloniträdgårdsområden för att se hur många stugor som använder sig av enskilda avlopp samt att informera kolonister om att dessa enskilda avlopp inte får förekomma. Resultaten visar även på en svårighet att ge ett fullgott svar på frågan om koloniträdgårdar läcker näringsämnen till Drevviken. Förmodligen gör de det men mängden diffus tillrinning är svår att mäta och skulle dessutom bli mycket tidskrävande att undersöka. / The purpose of this study was to investigate if allotment gardens in the Drevviken area leak nutrients into nearby lakes and streams. The basis for the study comes from a qualitative interview with three representatives from the Environmental Administration in Stockholm Municipality, as well as literature. The results show that there is a problem that the colonists use their own wastewater solutions which are not allowed under their lease agreement. Stockholm City is committed that running water still will not be allowed to occur despite efforts made ​​by Skarpnäcks stadsdelsnämnd of designing good wastewater solutions for cottages in the allotment areas. These wastewater solutions were developed over two years within the project Ability to organize drains in parts of the Listudden allotment area. The only action that presently exists is to follow the lease agreement and problems with leaking allotment gardens would no longer be a problem. However, no efforts to combat the problem are being made. No inventories of sewage treatment at the allotments are made ​​today, and no information is distributed to colonists on what applies.  In the action programs concerning Drevviken, the basis for the study, inventory of sewage treatment at the allotment areas and information to the colonists are proposed. The results also show a difficulty to give a satisfactory answer to the question if allotment gardens leak nutrients. Probably they do leak but the amount of diffuse runoff is difficult to measure and would be very time consuming to study.