Rozprawy doktorskie na temat „Liquid storage tank”

Boilover is a violent ejection of certain liquid hydrocarbons due to prolonged burning during a storage tank fire. It happens due to vaporization of the water sub-layer that commonly resides at the base of a storage tank, resulting in the ejection of hot fuel from the tank, enormous fire enlargement, formation of a fireball and an extensive ground fire. Boilover is a very dangerous accidental phenomenon, which can lead to serious injuries especially to emergency responders. The boilover can occur several hours after the fuel in a storage tank caught fire. The delayed boilover occurrence is an unknown strong parameter when managing the emergency response operations. Modelling and simulation of the boilover phenomenon will allow the prediction of the important characteristics features of such an event and enable corresponding safety measures to be prepared. Of particular importance is the time from ignition to the occurrence of boilover. In order to establish a tool for the prediction of the boilover events, it is essential to understand what happens within the fuel during a fire. Such understanding is important in order to recognize and determine the mechanisms for the hot zone formation and growth which are essentials, especially for predicting the onset time of boilover. Accordingly, boilover experiments and tests were planned and carried out at field scale by the Large Atmospheric Storage Tank FIRE (LASTFIRE) project with the intentions to evaluate the nature and consequences of a boilover, and to establish a common mechanism that would explain the boilover occurrence. Undertaking field scale experiments, however, is difficult to carry out so often due to high costs and high safety concerns. In order to obtain more detailed measurements and visual records of the behaviour of the liquids in the pool, a novel laboratory scale rig has been designed, built and commissioned at Loughborough University. The vessels used in the field scale tests and the laboratory scale rig were instrumented with a network of thermocouples, in order to monitor the distribution in temperature throughout the liquid and its variation with time. The temperature distribution variation as a function of time enabled the recognition of the phases of the evolution of the hot zone and hence the mechanism of boilover. The rig has allowed well defined and repeatable experiments to be performed and hence enable to study and assess boilover in a reproducible manner. In addition, visualisation of the fuel behaviour during the experiments could be obtained to better understand the formation and growth of hot zone, the boiling of water layer and hence the boilover occurrence. A number of small and larger scale experiments had been completed to obtain a wide spectrum of results, evaluating the effect of tank diameters, fuel depth, and water depth on the rate and extent of the boilover. The analysis of the results had elucidated further the processes of the hot zone formation and its growth, and hence mechanisms involved in the boilover occurrence. The important observation was that there are three stages observed in the mechanism of boilover incidence. At the start of the fire there is a stage when the hot zone is formed. This is followed by a period when the bottom of the hot zone moves downwards at a pseudo constant rate in which the distillation process (vaporisation of the fuel s lighter ends) is taking place. The final stage involved the heating up of the lowest fuel layer consisting of components with very high boiling points and occurrence of boilover. Based on the observations of the mechanisms involved in the hot zone formation and its growth, predictive calculations were developed which focus on the provision of an estimate on the time to boilover upon the establishment of a full surface fire and an estimate of the amount of fuel remaining in the tank prior to the occurrence of the boilover. A predictive tool was developed in order to provide predictions on the important parameters associated with a boilover event i.e. the time to boilover, the amount of fuel remaining in the tank prior to boilover and hence the quantity of fuel that would be ejected during boilover and the consequences of a boilover i.e. fire enlargement, fireball effects and the ground area affected by the expulsion of oil during a boilover event. The predictive tool developed is capable of providing good estimates of onset time to boilover and predicts consequences of the boilover. The tool predicting the time to boilover of the LASTFIRE field scale test and the laboratory scales tests was shown to produce predictions that correlated with the observed time to boilover. Apart from the time to boilover, the predictive calculation is also able to provide an estimate of fuel amount remained in the tank at the instance of boilover occurrence. Consequently, the tool is capable of predicting the quantity of burning fuel being ejected and hence the area affected by the extensive ground fire surrounding the tank. The predictive results are conservatives but yet show good agreement with observed time to boilover in real boilover incidents. Certain considerations in the development of safe and effective fire fighting strategies in handling fire scenario with a potential of boilover occurrence, can be assessed using the predictive tool developed.

A widespread rollout of alternative fuels is desirable to mitigate the issue of global warming. Hydrogen is widely considered one of the most promising solutions to reduce the environmental impact of the transport sector. This thesis work, performed in collaboration with the Norwegian University of Science and Technology NTNU, is based on the numerical study of the boil-off rate (BOR) of liquid hydrogen. The BOF represents the amount of liquid hydrogen that evaporates and that must be vented, through a pressure relief valve, in order to avoid the overpressurization of the tank. The case study considered is a cryogenic tank with a maximum capacity of 900 kg used as storage system in a liquid hydrogen refueling station. Two different insulation systems were considered: the high-vacuum multilayer (MLI) and the polyurethane foam insulation. The numerical computation was performed with OpenFoam , a computational fluid dynamics (CFD) open-source software. In order to accurately simulate the evaporation process that takes place inside the tank the Lee evaporation model and the kinetic gas evaporation model were used and critically compared. The results obtained show a great difference in terms of BOR between these two insulation systems. A layer of 15 mm of MLI makes it possible to obtain a BOR value an order of magnitude lower than that obtained with 1 meter of polyurethane foam.

Liquid storage tanks are a crucial type of structures. They are used to store various types of liquids and liquefied gases in different situations. In seismic regions, functionality of these structures after severe earthquakes is an important factor in their design. In earthquake-prone regions, the sloshing phenomena has an important role in the design procedure. Current design codes and guidelines (e.g. ACI 350.3 and ASCE 7) are based on analytical studies that in some cases can be inaccurate in prediction of forces and pressures. Since a long time ago scientists have studied the sloshing phenomena in liquid storage tanks with different methods including analytical, numerical and experimental studies. In the current study, rectangular ground-supported tanks are studied and the effect of seismic loading on them is investigated both experimentally and numerically. For the experimental tests, the tanks were placed on a shaking table and using high-speed HD cameras, tests were filmed and later analyzed frame by frame to capture the critical moments. To investigate the bi-lateral effect of base excitation on the tanks, they were oriented on the table with four different angles. In the numerical study, a computational fluid dynamics tool - OpenFOAM - was used to simulate the tank motion and finally the results were compared with the experiment in order to develop a reliable model.

Two underground concrete manure reservoirs of 70 m$ sp3$ were tested for their infiltration rate to water as well as to 1% and 3% total solid dairy manure. Positive and negative infiltration were measured for the water test while only negative infiltration was measured with the manure.
Positive infiltration is met when the water table into the soil is above the liquid level into the reservoir. In that case, the water is moving from the outside to the inside of the reservoir. An opposite situation is met when the infiltration is negative.
From the results, the infiltration rate varied from 0.00 to 6.684 $ times$ 10$ sp{-7}$ m/s. The minimum value was recorded at the reservoir 55 with 1% of total solid manure and the maximum value was recorded with same reservoir with positive pressure to water.

Le développement durable nécessite des investissements massifs pour l'exploration et l'utilisation des sources d'énergie renouvelables dans le bilan énergétique. Parmi diverses formes de l’énergie, l'électricité est sans doute la forme la plus souhaitable pour les usages quotidiens. Cependant, en raison de l'intermittence des sources d’énergie renouvelables, l'électricité doit être stockée sous d'autres formes afin de corréler la production éphémère et la consommation en continue. Malgré la présence des systèmes commerciaux de stockage d'énergie, la recherche de nouveaux matériaux et de nouvelles approches pour résoudre ce problème est toujours en cours et attire également une grande attention. Les récents progrès ont poussé la communauté scientifique vers l'utilisation de matériaux à l'échelle nanométrique pour des systèmes de stockage et de conversion de l'énergie. Bien que ces derniers offrent des avantages pour réduire les émissions de gaz à effet de serre, leurs performances sont encore inférieures aux valeurs théoriques. Dans ce contexte, l’ingénierie à l'échelle moléculaire devient cruciale non seulement pour créer un nouveau type d'entités moléculaires mais aussi pour augmenter les performances des matériaux existants. Dans ce contexte, nous proposons d’utiliser une nouvelle famille de matériaux à base de liquides ioniques pour diverses d’applications, comprenant celles dans le domaine énergétique et pour le long terme, dans la fabrication de la peau artificielle, ces objectifs font l’objet de ces travaux de thèse. Cette dissertation est composée de cinq chapitres. Le chapitre 1 présente différents aspects des liquides ioniques (LIs) et des polymères à base de LI décrites dans la littérature. Via ce chapitre, nous envisageons d’atteindre les points suivants : (1) Décrire les utilisations possibles des liquides ioniques en électrochimie ; (2) Discuter des comportements physico-chimiques de ces composés en solution, (3) Montrer l'immobilisation de liquides ioniques (Redox-actifs) sur différents substrats : de couches minces aux polymères et (4) Mettre en évidence les travaux marquant portant sur l’utilisation des polymères ioniques liquides dans diverses applications. Le chapitre 2 présente différentes approches électrochimiques pour l'immobilisation de liquides ioniques rédox à la surface de l'électrode. De plus, les différentes caractéristiques des nouvelles interfaces seront reportées. Le chapitre 3 se concentre sur l'utilisation des polymères LIs comme catalyseurs émergents et comme matrices pour la génération de matériaux hybrides vers l'activation de petites molécules (ORR, OER, HER). Le chapitre 4 étudie la réactivité à l'échelle micro / nanométrique de divers matériaux, y compris les polymères liquides ioniques électro-actifs, en utilisant la microscopie électrochimique à balayage (SECM). Le chapitre 5 présente les résultats préliminaires de la fabrication de substrats flexibles avec des fonctionnalités intéressantes : possibilité de convertir le frottement en électricité et stockage d'énergie en utilisant des liquides ioniques redox polymériques. Ces études ouvrent de nouvelles opportunités pour élaborer des dispositifs flexibles, portables et implantables
Increasing demand of energy requires massive investment for exploration and utilization of renewable energy sources in the energy balance. However, due to the intermittence of the current renewable sources, the generated electricity must be stored under other forms to correlate the fleeting production and the continuous consumption. Despite available commercialized systems, seeking for new materials and new approaches for resolving this problem is still matter of interest for scientific researches. Highlighted advancements have recently oriented the community towards the utilization of nanoscale materials for efficient energy storage and conversion. Although the advantages given by existing nanomaterials for diverse applications, especially in the energy field, their performance is still lower than theoretical purposes. Consequently, tailoring the physical-chemical properties at the molecular scale becomes crucial not only for boosting the activities of the existed materials but also for creating a new type of molecular entities for storing and releasing the energy. Accordingly, this PhD work aim to develop new family of materials based on ionic liquid that exhibits a multifunctionality towards energy applications. Our work is based on the knowhow in surface functionalization and material preparation by simple methods to build up electrochemical systems that can be utilized in various applications. Thus, this thesis will report different results obtained by following this direction and is composed of six chapters: Chapter 1 reports an overview of ionic liquid and polymeric ionic liquid. We propose to review the available literature on the redox-IL from solution to immobilized substrates. Through this chapter, we will achieve the following points: (1) Report the possible uses of ionic liquids in electrochemistry; (2) Discuss about the physical-chemical behaviors of these compounds in solution, (3) Show the immobilization of (Redox-active)–ionic liquids onto different substrates: from thin layer to polymer and (4) Highlight recent advances using polymeric ionic liquids for diverse applications. Chapter 2 will be devoted to different electrochemical assisted approaches for the immobilization of (redox)-ionic liquids to the electrode surface. We will focus on generating a thin layer and polymeric film based ionic liquid. Furthermore, the different characteristics of the new interfaces will be reported. Chapter 3 concentrates on the use of the polymer ionic liquid modified electrodes as emerging catalyst and as template for the generation of hybrid materials towards activation of small molecules. Chapter 4 studies the reactivity at micro/nanometer scale of diverse materials, including single layer graphene, polymeric redox – ionic liquid, using the scanning electrochemical microscopy (SECM). Chapter 5 reports the potential applications of redox ionic liquid and focus on providing the preliminary results towards the fabrication of flexible substrates with interesting functionalities: possibility to convert the friction to electricity and energy storage by using polymeric redox ionic liquids. These studies open a new opportunity to elaborate flexible, wearable and implantable devices. Finally, some concluding remarks are given to summarize different results obtained in the previous chapters. Besides, different perspectives will be given by using ionic liquid as main material for developing different energy storage and conversion systems

碩士
國立臺灣大學
土木工程學系
85
Liquid storage tanks are critical components of gas and liquid fuel lifeline transition and distribution system. Failure of these structures could curtail operation ofthe whole system. The safty hazard associated with the rupture consequence of failure. This is particularly obvious in a highly populated urban area. The vulnirability of tanks to seismic ground motions has been observed in many major past earthquakes. Since our country is located in a seismically active region, it is indeed urgent to propose a guidline to perform the safety evaluation of storage tanks on the basis of there earthquake resistant strength. In fact, this is exactly the objective of the study. This project will investigate the response characteristics ofliquid and storage tanks subjected to seimic ground motions. Several failure modes, e.g. buckling of shell, damage to the roof are considered. Only simple and practical procedures are adopted. The emphasis of the project is laid on the establishment of a design criterion and a safety evaluation guideline by which the industry may utilize to reduce the earthquake threat.

博士
國立臺灣大學
土木工程學研究所
91
The interaction between liquids and structures is emphasized in this study. First of all, the numerical approach for the liquid sloshing phenomenon inside a rigid tank subjected to a horizontal excitation is established. The liquid is assumed to be potential flow. Therefore, the Boundary Element Methods with the Lagrangian coordinate description and Taylor series expansion is applied to solve the non-linear sloshing problem. The hydrodynamic pressure on the tank wall is obtained by the use of the Bernoulli’s Equation, and the base shear force due to liquid sloshing can be calculated by the integration of the hydrodynamic pressure along the tank wall. Second, the base shear force is applied on the structure to simulate the interaction between liquids and structures. Then the space state vector method is treated to solve the transient structural responses. Hence, the interaction between liquids and structure can be studied by the present numerical scheme in detail. In this study, both numerical simulations and scaled model tests are adopted for the investigations of two engineering applications as following. The seismic isolation of rigid liquid-storage tanks is considered as the first application in this work. Based on the experimental and numerical results, an isolator with long natural period can deduce the seismic responses of the storage tank significantly, such as the tank acceleration, the base shear force, and the wave elevation. Second, the Tuned Liquid Damper (or TLD) is also investigated in the present work. The careful discussion on the mechanism of the TLD’s vibration-reduction ability is intensively addressed. In general, the TLD can mitigate structural vibrations efficiently while the liquid natural frequency is close to the one of the main structure. The damping coefficient of the liquid inside the TLD is also a very important factor for the effectiveness of vibration suppression. The agreements between the numerical and experimental results are very good in the two application examples. Therefore, the more numerical and experimental efforts described in the present work should be encouraged to apply on other case studies of the interaction between liquids and structures.

A systematic study is carried out on several aspects of the dynamic response of liquid containing, cylindrical steel tanks that may experience partial uplifting of their base during intense ground shaking. The tanks are presumed to rest on a rigid base and to be subjected to unidirectional horizontal ground motion. The objective is to formulate a method of analysis with which the dynamic response of such systems may be evaluated reliably and cost-effectively. The study consists of two parts: the first deals with the static uplifting resistance of the flexible base plate, and the second deals with the dynamic response of the uplifting system. In Chapters 2 and 3, an insight into the behavior of the uplifting plate is gained with the help of a prismatic beam solution. In Chapter 2, the solution is implemented 'exactly' whereas, in Chapter 3 it is implemented approximately by use of the Ritz energy procedure with a set of judiciously selected deflection shape functions. In Chapter 4, the 'exact' solution of the axisymmetrically uplifted plate is obtained. A detailed comparison is then made between the plate and the beam solutions in order to ascertain the suitability of the beam model for the plate analysis. The insight gained from this comparison is then utilized in the formulation of an approximate method of analysis for the solution of an asymmetrically uplifted plate. In obtaining the beam and plate solutions, due consideration is given to the effects of membrane forces associated with large deflections, plastic yielding in the base plate, and the restraining action of the tank wall at the plate boundary. In Chapter 5, an approximate method of analysis is formulated for efficiently computing the seismic response of uplifting tanks. Both unanchored tanks and partially anchored tanks for which the number of anchor bolts at the base is insufficient to ensure full fixity are considered. The responses examined include the hydrodynamic pressures, the base uplift at critical locations, the plastic rotation at the plate-shell junction, and the maximum compressive stress in the tank wall. The parameters that are varied include the intensity of ground shaking, the geometric and material properties of the tank, and the degree of base fixity.

Because of cost, cylindrical, ground supported liquid storage tanks are often not fixed to their foundation, even in seismic areas. For such an unanchored tank made of steel, the weight of the cylindrical shell is mostly insufficient to prevent local uplift due to seismic overturning moments. Although, for properly designed connecting pipes, uplift itself is not a problem, it results in larger vertical compressive stresses in the tank wall at the base, opposite to where the uplift occurs. These compressive stresses have often caused buckling, even in earthquakes which did not cause much damage to other structures.

Various investigators have studied the behavior of unanchored tanks experimentally, but, due to the complexity of the problem, so far very little theoretical work has been done. Two methods of analysis for static lateral loads are presented: An approximate one in which the restraining action of the base plate is modeled by nonlinear Winkler springs, and a more comprehensive one in which the two dimensional nonlinear contact problem is solved by the finite difference energy method. The theoretical results are compared with existing experimental results and with the approach from current U.S. design standards. The theoretical peak compressive stresses are in good agreement with the experimental results, but in some cases exceed those calculated by the code method by more than 100%.

Finally, a new design concept, by which the tank wall is preuplifted all around its circumference by inserting a ring filler is described. It will be shown theoretically and experimentally that this preuplift method substantially improves the lateral load capacity.

碩士
中華科技大學
土木防災工程研究所
98
The objective of this research is to develop the fragility curves of rectangular reinforced concrete liquid storage tanks subjected to various site conditions and different earthquake source mechanism. Chen-Kianoush distributed mass model is adopted in this research rather than Housner’s lumped mass model. The former model has been verified, which can achieve a more consistent with the nonlinear time history analysis. A nonlinear pushover analysis is performed to achieve a capacity curve with a different reinforcement. The ductility of displacements at the top of tank is used to classify damage states. This serves as a basis to conduct a rigorous nonlinear time history analysis with various site conditions and different source mechanism. The fragility curves constructed in this research can be implemented in the hazard planning.

This dissertation consists of four parts. The first part deals with the response of liquid storage tanks to a vertical component of ground motion. Galerkin's method is used to solve this problem approximately, and its accuracy is established by comparing the results with those obtained by the exact modal superposition method. The effects of soil structure interaction are examined, and a simple practical design procedure is proposed for providing for these effects. The second part deals with the response of liquid storage tanks to a horizontal component of ground shaking. The problem is analyzed by application of the Rayleigh-Ritz procedure in combination with Lagrange's equation. The details of the method of analysis are presented along with comprehensive numerical data which may be used readily in design applications. The third part of the dissertation deals with the response of liquid storage tanks, both rigid and flexible, to a rocking component of ground shaking. Emphasis is placed on understanding the behavior of the tank-liquid system and establishing the interrelationship of the responses of the system to rocking and to a lateral, translational motion. The fourth part deals with the harmonic response of massless ring foundations supported on a homogeneous elastic halfspace and subjected either to a vertical force or an overturning moment. The theory of elastic wave propagation is used to obtain the impedance functions. The method of analysis takes due account of the mixed boundary conditions at the surface of the halfspace. The effect of foundation mass on the response is also studied for the vertically excited system. The reported data are believed to be of high accuracy.

This dissertation presents a comprehensive study of the dynamic response of storage tanks containing high-level radioactive wastes in nuclear facilities. Of the many issues that are peculiar to these systems, four important ones have been studied. Accordingly, the study is presented in four parts. The first part deals with the dynamic response of flexible tanks that are placed inside concrete vaults and are attached to the vaults both at the top and the bottom. The tanks are presumed to be fixed at the base and supported by either a roller or a hinge at the top. The response quantities examined include the natural frequencies of vibration, the hydrodynamic pressures and the induced tank forces. The general trends are established by comparing the response quantities for the top-constrained systems with those for base-excited cantilever systems. The second part deals with the response of rigid and flexible tanks containing stratified liquids. The liquid is considered to be arranged in layers with varying layer thicknesses and mass densities, or to be inhomogeneous with a continuously varying mass density. In addition to the free vibrational sloshing characteristics of the liquid, the responses examined include the vertical displacements at the free surface, and the impulsive and convective components of the hydrodynamic wall pressures and associated tank forces. A simplified analytical procedure that estimates the response quantities for the layered systems from corresponding solutions for homogeneous systems is also presented. The third part presents an exploratory study for assessing the effects of tank-base flexibility on the response of vertically excited liquid storage tanks. A suitable model of the tank-liquid-foundation-soil system is considered, and the natural frequencies, the associated damping ratios and the induced pressures are studied for a wide range of base-flexibility values. The final part estimates the effects induced by the impact of the sloshing liquid on the tank roof. Consideration is given not only to the effects that are induced on the roof but also to the effects that are transferred to the side-wall. Both rectangular and cylindrical systems are considered and the effect of changing the slope of the roof on the induced impact effects is also studied.

A comprehensive study of the response of liquid storage tanks subjected to ground induced lateral excitations is presented. Wall flexibility affects the response coefficients of tall tanks significantly. In general, response coefficients for tanks are relatively insensitive to super-structure parameters. A simplified procedure for evaluating inertial interaction effects is considered. While foundation translation dominates the response of broad tanks, foundation rocking is important for tall tanks. Exact values and approximate expressions reveal that the effects of interaction are a function of the relative flexibilities of the medium and super-structure. Effects of ground motion incoherence are evaluated by formal stochastic and approximate semi-deterministic approaches. Kinematic interaction reduces the response of tanks. The reductions are generally small, particularly for tall tanks. Inertial interaction effects are generally substantially larger than corresponding kinematic interaction effects. Inertial interaction normally reduces the response of broad tanks, but can increase the response of tall tanks.

碩士
中國醫藥大學
公共衛生學系碩士班
104
Background: This is the first study conducting the health risk assessment on airborne toxics emissions from storage tanks in Taiwan. The proposed site was applied for environmental impact assessment with 111,701.43 m2 and 2,880,000 tons of annual net throughputs. Currently, there are no templates recognized by Taiwan Environmental Protection Agency (EPA) to estimate the emissions of a single component from specific stored liquid mixture. This makes it difficult to characterize the health risk to the surrounding residents. Objective: This study followed “Technical Guideline of Health Risk Assessment” published by Taiwan EPA in 2011, which requires using the conservative scenario when the actual exposure conditions are not certain for conducting health risk assessment. The estimation of emission complies with “Emission Calculation Handbook of Stationary Pollution Sources” by Taiwan EPA and “AP-42 empirical formulae” by USEPA. In addition, we established a calculation template of single component of mixture liquids for evaluating their emission loss and the associated health risks. Methods: For conservative scenario, we proposed a three-steps screening procedure for organic liquids disposition by storage tank type, emission total loss, and risk strength. From the 17 chemical species of organic liquids, we identified 23 chemical components from MSDS. For risk calculation purpose, we evaluated 5 types of emission source, including fixed roof tanks total loss, internal floating roof tanks total loss, tank truck loading emission, equipment leak emission, and total loss during cleaning. Average gaseous concentration were simulated by the ISC3 dispersion model on the proposed site of 10 km × 10 km area with 200 m resolution using five years (2009~2013) hourly meteorological data. The stimulated results were input to FRAMES/MEPAS multimedia models with 5 exposure pathways for risk estimation, and the results were used to produce 5-grade risk map with ArcGIS. Results: The mixed liquid generating the 3 highest emissions was naphtha, diesel fuel and gasoline, which contributed approximately 44%, 21% and 12%. Among the 23 components of emissions, the top 4 toxics were pentane, hexane, p-xylene and toluene, which accounted for 64% of total emissions. The predicted excess lifetime cancer risk (ELCR) showed a mean and P95 value of 0.3E-06 and 0.9E-06, and hazard index (HI) of 1.9E-03 and 6.6E-03, respectively, which were lower than the acceptable cancer and non-cancer risk criteria. This analysis also showed that the air intake contributed 97% to 99% of total risk. Benzene was the major contributor of cancer risk with 46.6% and naphthalene in second with 41.0%. The primary contributors of non-cancer risk were naphthalene for 59.4% and benzene for 28.5%. The excess cancer risk maps indicated that the hotspot of ELCR is located around the harbor, and the excess non-cancer risk maps reveal the hotspot of HI was situated at the southern part of the site; the both maps displayed a dispersion direction toward the south. Conclusions: The predicted risk was acceptable under the conservative scenario set up for this study. Because the vapor pressure will increase in high ambient temperature periods, we suggest that the storage tanks be operated as much as possible in winter or at night to minimize the emission losses. Furthermore, the monitoring station can be set up in the hotspot to verify our study outcomes when the site is in operation.

Light Non-Aqueous Phase Liquids (LNAPLs) are used throughout the world for numerous applications, the most well-known being automotive fuels, such as petrol and diesel. The widespread production, distribution, storage and use of LNAPLs results in the ubiquitous occurrence of spillage to ground (Geller et al, 2000). Considering the hazardous nature of most LNAPLs due to their explosive and toxic characteristics, releases of LNAPLs to ground have well documented human health and ecological consequences. The occurrence of leaking underground and above-ground storage tanks at service stations and consumer installations is a common cause of contamination; and is described in literature for various countries of the world (Dietz et. al., 1986; Moschini et al, 2005; Mulroy and Ou, 1997; Harris, 1989; The Institute of Petroleum, 2002). Little failure data are however available for the South African context. In addition to this, data concerning the location and characteristics of sites storing LNAPLs in South Africa is similarly scarce. The study analysed data from three sources, namely the eThekwini Fire and Emergency Services data, GIS data and data from a local consultancy, in order to determine whether certain factors increased contamination risk posed by these facilities. The results indicated that contamination may be a result of numerous factors, but primarily line and tank failure. The type of installation was also found to have a significant influence on whether a site would be contaminated or not. In addition to the above, the results indicated that certain circumstances increase the severity of loss. The results indicated the need for more investigation to be performed into contamination as a result of LNAPL loss to ground, and the need for protective measures to be implemented for high risk sites where the likelihood and severity of a potential loss is high. Focus should then be centred on the probability of failure of non-ferrous pipework and GRP tanks to ensure adequate protective mechanisms are in place in the event of a failure of this newer infrastructure. In addition, a review of regulatory control of LNAPL storage in South Africa and the eThekwini Municipality, with reference to the international context, indicated the need for a specific department within the local government structure that manages LNAPLs with the objective of reducing contamination incidents. The continued use of underground storage of LNAPLs will always present a risk of failure/contamination due to the unseen nature of the installations and related infrastructure. It is this risk that requires regulatory management. Details of contaminated sites in South Africa should be within the public domain.
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.