This study compared four different water main failure prediction models: a statistically simple model, a statistically complex model, a statistically complex model with modifications termed the 2019 model, and an age-based model. The statistically complex models compute the probability of failure based on age, size, internal pressure, length of pipe in corrosive soil, land use, and material of the. These two values are then used to prioritize a water main rehabilitation program to effectively use the municipality’s funds. The 2019 model calculates the probability of failure and consequence of failure differently than the statistically complex model by considering corrosive soil data instead of assuming all the pipes are in highly corrosive soil and average daily traffic volume data instead of using street classifications. The statistically simple model only uses the pipe age and material for probability of failure. The age-based model relies purely on the age of the pipe to determine its probability of failure. Consequences of failure are determined by the proximity of the pipe to highly trafficked streets, critical services, pipe replacement cost, and the flow capacity of the pipe. Risk of failure score is the product of the consequence of failure score and probability of failure score. Pipes are then ranked based on risk of failure scores to allow municipalities to determine their pipe rehabilitation schedule. The results showed that the statistically complex models were preferred because results varied between all four models. The 2019 model is preferred for long-term analysis because it can better account for future traffic growth using the average daily traffic volume. Corrosive soil data did not have a significant impact on the results, which can be attributed to the relatively small regression parameter for corrosive soil. The age-based model is not recommended because results of this study shows it places a significantly high number of pipes in the high and critical risk categories compared to the other models that account for more factors. This could result in the unnecessary replacement of pipes leading to an inefficient allocation of funds. Keywords: Risk of Failure, Consequence of Failure, Probability of Failure

The European Commission had approved the Registration, Evaluation and Authorization of Chemicals (REACH) regulations in the year 2006, and will begin to implement it form 1 June 2007. This regulation greatly increases safety of protection for the users of chemicals, but it also brought a problem for the manufactures as well as downstream users. That is they have to generate and distribute much more Material Safety Data Sheets (MSDS) then before. This work is difficult for most companies since this job usually was done manually. The new regulation requires a much more efficient method to generate and distribute them. This thesis project addresses the problem of automatically distributing MSDS and the corresponding metadata. It presents the underlying technology selected for this project. It gives a brief introduction of this project, the underlying technologies used, along with the methods used to deliver relevant and up to date materials safety information. At last an HTTP web application approach was selected to solve the problem, the resulting application can efficiently notify a downstream user of the newly updated MSDS and transport the corresponding file and metadata. It is truly data driven, therefore the downstream user does not need to check for updates everyday, instead will be notified when there is an available update. / Den Europeiska kommissionen antog 2006 en ny bestämmelse för informationsspridning av kemikalier, Registration, Evaluation, and Authorization of Chemicals (REACH), och den kommer att tas i bruk från första juni 2007. Bestämmelsen innebär ett starkt ökat skydd för användare av kemikalier, men den ställer även till problem för både tillverkare och användare. Exempelvis, de måste generera och distribuera betydligt fler materialsäkerhetsföreskrifter, Material Safety Data Sheets (MSDS), än tidigare. Detta arbete är krävande för de flesta företag eftersom arbetet ofta sker manuellt. Den nya bestämmelsen kräver mycket effektivare metoder att generera och distribuera MSDS. Det här examensarbetet fokuserar på problemet att automatiskt distribuera MSDS och den korresponderande metadatat. Rapporten presenterar den underliggande teknologin för examensarbetet. Därutöver ges en kort introduktion till examensarbetet, den underliggande teknologin, tillsammans med de metoderna som används för att skicka relevanta och aktuella materialsäkerhetsföreskrifter. Som avslutning väljs en HTTP Web applikationslösning för att lösa problemet. Den lösningen kan effektivt underrätta en användare att det finns en nyare MSDS och sedan skicka den korresponderande filen och dess metadata. Den är data driven, vilket gör att en användare inte måste kontrollera för uppdateringar varje dag, utan kommer att bli informerad när det finns en ny tillgänglig.

This thesis documents the relationship among the major water quality parameters during a nitrification episode. Nitrification unexpectedly occurred in a chloraminated pilot drinking water distribution system practicing with a 4.0 mg/L as Cl2 residual dosed at 4.5:1 Cl2:NH3-N. Surface, ground and sea water were treated and disinfected with monochloramines to produce finished water quality similar to regional utility water quality. PVC, galvanized, unlined cast iron and lined iron pipes were harvested from regional distribution systems and used to build eighteen pilot distribution systems (PDSs). The PDSs were operated at a 5-day hydraulic residence time (HRT) and ambient temperatures. As seasonal temperatures increased the rate of monochloramine dissipation increased until effluent PDS residuals were zero. PDSs effluent water quality parameters chloramines residual, dissolved oxygen, heterotrophic plate counts (HPCs), pH, alkalinity, and nitrogen species were monitored and found to vary as expected by stoichiometry associated with theoretical biological reactions excepting alkalinity. Nitrification was confirmed in the PDSs. The occurrence in the PDSs was not isolated to any particular source water. Ammonia for nitrification came from degraded chloramines, which was common among all finished waters. Consistent with nitrification trends of dissolved oxygen consumption, ammonia consumption, nitrite and nitrate production were clearly observed in the PDSs bulk water quality profiles. Trends of pH and alkalinity were less apparent. To control nitrification: residual was increased to 4.5 mg/L as Cl2 at 5:1 Cl2:NH3-N dosing ratio, and the HRT was reduced from 5 to 2 days. Elimination of the nitrification episode was achieved after a 1 week free chlorine burn.

Biostability and related issues (e.g. nitrification) were investigated for 18 months in 18 pilot distribution systems, under various water quality scenarios. This study specifically investigated the impact of steady-state water changes on HPC levels in chlorinated and chloraminated distribution systems. Chlorination was more effective than chloramination in reducing HPC levels (1-2 log difference). There was a rapid increase in HPC corresponding to the change in steady-state water quality, which was observed in all PDS. Modeling effort demonstrated that HPC levels reached a maximum within five days after water quality change and return to initial level ten days after the change. Since alkalinity was used as a tracer of the steady-state water quality change, time to reach maximum HPC was related to a mixing model using alkalinity as a surrogate that confirmed alkalinity transition was complete in approximately eight days. Biostability was assessed by HPC levels, since no coliform were ever detected. It was observed that HPC levels would be above four logs if residual droped below 0.1-0.2 mg/L as Cl?, which is below the regulatory minimum of 0.6 mg/L as Cl?. Therefore bacterial proliferation is more likely to be controlled in distribution systems as long as residual regulatory requirements are met. An empirical modeling effort showed that residual, pipe material and temperature were the most important parameters in controlling HPC levels in distribution systems, residual being the only parameter that can be practically used by utilities to control biological stability in their distribution systems. Use of less reactive (i.e. with less chlorine demand) pipes is recommended in order to prevent residual depletion and subsequent bacterial proliferation.This study is investigated biofilm growth simultaneously with suspended growth under a wide range of water quality scenarios and pipe materials. It was found that increasing the degree of treatment led to reduction of biofilm density, except for reverse osmosis treated groundwater, which exerted the highest biofilm density of all waters. Biofilm densities on corrodible, highly reactive materials (e.g. unlined cast iron and galvanized steel) were significantly greater than on PVC and lined cast iron. Biofilm modeling showed that attached bacteria were most affected by temperature and much less by HRT, bulk HPC and residual. The model predicts biofilms will always be active for environments common to drinking water distribution systems. As American utilities do not control biofilms with extensive and costly AOC reduction, American utilities must maintain a strong residual to maintain biological integrity and stability in drinking water distribution systems.Nitrite and nitrate were considered the most suitable indicators for utilities to predict onset of a nitrification episode in the distribution system bulk liquid. DO and ammonia were correlated to production of nitrite and nitrate and therefore could be related to nitrification. However since ammonia and DO consumptions can be caused by other phenomena than nitrification (e.g. oxidation by disinfectant to nitrite and reduction at the pipe wall, respectively), these parameters are not considered indicators of nitrification.Ammonia-Oxidizing Bacteria (AOB) densities in the bulk phase correlated well with nitrite and nitrate production, reinforcing the fact that nitrite and nitrate are good monitoring tools to predict nitrification. Chloramine residual proved to be helpful in reducing nitrification in the bulk phase but has little effect on biofilm densities. As DO has been related to bacterial proliferation and nitrification, it can be a useful and inexpensive option for utilities in predicting biological instability, if monitored in conjunction with residual, nitrite and nitrate. Autotrophic (i.e. AOB) and heterotrophic (i.e. HPC) organisms were correlated in the bulk phase and biofilms.

No description available.

Yes / Distributed generators (DGs) are a reliable solution to supply economic and reliable electricity to customers. It is the last stage in delivery of electric power which can be defined as an electric power source connected directly to the distribution network or on the customer site. It is necessary to allocate DGs optimally (size, placement and the type) to obtain commercial, technical, environmental and regulatory advantages of power systems. In this context, a comprehensive literature review of uncertainty modeling methods used for modeling uncertain parameters related to renewable DGs as well as methodologies used for the planning and operation of DGs integration into distribution network. / This work was supported in part by the SITARA project funded by the British Council and the Department for Business, Innovation and Skills, UK and in part by the University of Bradford, UK under the CCIP grant 66052/000000.

Failure of pipes in water distribution systems is a common occurrence especially in large cities. The failure of a pipe results in: loss of water; property damage; interruption of service; decreased system performance; and the financial cost of restoring the failed pipe. The cost of replacement and rehabilitation in the United States is estimated at 23 plus billion dollars. It is virtually impossible to replace all vulnerable pipes at the same time. As a result, there is a need for methods that can help in progressive system rehabilitation and replacement subject to budgetary constraints. If delaying is considered a good strategy due to the time value of money then, the timing of preventive maintenance becomes a crucial element for system maintenance and operation. The central under pinning element in the decision process for scheduling preventive maintenance is the deteriorating nature of a pipe under a given surrounding. By planning to replace pipes before they fail, proper planning can be put in place for securing of finances and labor force needed to rehabilitate the pipes. With this approach, service interruptions are minimized as the loss of service time is limited to the time used in replacing the pipe. In this research, a mechanistic model for assessing the stage of deterioration of an underground pipe is developed. The developed model consists of three sub-models namely, the Pipe Load Model (PLM), the Pipe Deterioration Model (PDM), and the Pipe Break Model (PBM). The PLM simulates the loads and stresses exerted on a buried water main. These loads include the earth load, traffic load, internal pressure, expansive soil loads, thermal, and frost loads. The PDM simulates the deterioration of the pipe due to corrosion resulting from the physical characteristics of the pipe environment. The pipe deterioration effect is modeled in two stages. First, the thinning of the pipe wall is modeled using a corrosion model. Second, the localized pit growth is used to determine the residual strength of the pipe based on the fracture toughness and the initial design strength of the pipe. The PBM assesses the vulnerability of a pipe at any time in terms of a critical safety factor. The safety factor is defined as the ratio of residual strength to applied stress. For a conservative estimate the multiplier effect due to thermal and frost loads are considered. For a chosen analysis period, say 50 years, the pipes with safety factors less than the critical safety factor are selected and ordered by their rank. Aided by the prioritized list of failure prone pipes, utilities can organize a replacement schedule that minimizes cost over time. Additionally a physically based regression model for determining the optimal replacement time of pipe is also presented. A methodology for assessing the consequences of accelerated and delayed replacement is also provided. The methodologies developed in this dissertation will enable utilities to formulate future budgetary needs compatible with the intended level of service. An application of the model and results are included in the dissertation. / Ph. D.

This thesis describes the application of microprocessor based relays with internet communication capabilities in distribution protection systems. The traditional distribution protection system (recloser, sectionalizers) was configured to automatically isolate faulted circuits as well as to reenergize unfaulted loads after a certain number of reclosing operations. Internet Peer-to-Peer communication enables distribution relays to communicate with others connected to the communication network without having a master device. According to the results, the addition of peer-to-peer communication to a traditional distribution protection system significantly enhances its general performance eliminating undesired losses of unfaulted load. Additionally, it reduces outage duration as well as thermal and mechanical stress due to successive re-energizations under faults condition. / Master of Science

High-impedance faults (HIFs) on distribution feeders are abnormal electrical conditions that cannot be detected by conventional protection schemes. These faults pose a threat on human lives when neighboring objects become in contact with the line's bare and energized conductors. An accurate electrical model for a HIF is implemented to investigate typical patterns in the line's current that allow for the detection of these faults. The occurrence of HIFs is detected with harmonic-current phase analysis and localized with recloser-sectionalizer technology as presented in this work. A sectionalizer algorithm is then presented showing the decision criteria for HIF declaration and shown to discriminate against nominal behavior in distribution feeders of similar harmonic content. Finally, it is shown that the algorithm will not produce a misreading when a current transformer enters saturation. / Master of Science

Large public water utilities currently are required to take several 100 mL water samples every month in their distribution systems and to test these samples for the presence of total coliforms to comply with the Total Coliform Rule. How and where they take these samples is not specified. The Total Coliform Rule is currently undergoing review and revision. One possible revision is more specific rule language or guidance of where and when utilities take their monthly coliform water samples. This project considers various drinking water distribution system monitoring strategies for a large drinking water utility using simulations within an EPANET computer model of that utility's distribution system. A review of the literature and the use of best professional judgment help to inform the understanding of the primary causes of the occurrence of coliform bacteria in drinking water distribution systems. In this analysis, both contamination scenarios and coliform monitoring approaches are simulated in the EPANET computer model to better understand what types of contamination events might be detected by routine coliform monitoring and to what extent monitoring strategies affect observed results. In addition, statistical strengths of the various strategies and their respective results are considered in this project. Analysis of model output supports the assertion that water age may be a good factor to consider in designing a monitoring plan, especially if sampling cannot be conducted every day and that taking samples immediately after and in the vicinity of rapid changes in flow (e.g., during a firefighting incident) may help utility operators to better understand what associated risk, if any, exists to consumers of drinking water as a result of these flow conditions. / Master of Science