Construction Of Barriers Research Articles

Influence of sediment composition on morphology and internal structure of mixed siliciclastic–bioclastic coastal barriers: Contribution of flume experiments

ABSTRACTCoastal barriers are dynamic systems, the morphology and architecture of which are controlled by local hydrodynamics, sea‐level fluctuations at different timescales, geological heritage and sediment composition. Coastal barriers may be composed of siliciclastic sediments, bioclastic sediments, or a mixture of both. Mixed siliciclastic–bioclastic sediments (as common as ‘pure’ sediments) are still little represented in the literature. Changes in sediment composition could affect sedimentary processes which are involved in the construction and stability of coastal barriers due to a different hydrodynamic behaviour between bioclastic and siliciclastic particles. In this study, wave‐flume experiments were used to investigate the role of sediment compositional mixing on the morphology and architecture of coastal barriers. Three different siliciclastic/bioclastic mixtures were exposed to regular wave forcing, together with mean water level fluctuations to create regressive and transgressive depositional units. Compositional mixtures responded similarly in first‐order to mean water‐level fluctuations, with the formation of a bar at low water level. Its subsequent on‐shore migration and reworking as berm deposits during rising water level stages, and with the formation of washover deposits during high water level stages. In detail, the increasing content of bioclastic sediment increased the beachface slope and reduced the length of washover deposits. The faster aggradation of washover sheets with bioclastic‐rich mixtures accelerated the barrier recovery after a submersion and breaching event. A strong segregation between the siliciclastic and the bioclastic grains was observed in the different depositional units, which is attributed both to the coarse size (grain‐size control) and to the flat‐shape (compositional control) of the bioclastic particles.

Monitoring and mapping noise levels of university campus in central part of India

Introduction: Each one of us is directly or indirectly exposed to noise pollution in our daily life. Noise has chronic effect on the human but many of us are not aware. In our modern research platform very few studies are available for monitoring and mitigating of noise pollution compared to other environmental pollution.
 Materials and methods: This study has been designed to monitor, map the noise pollution in educational institute and find out the sources of noise followed by identification of hot spot. In this regards National Institute of Technology Raipur, Chhattisgarh, India was selected as study area. Noise levels measurements were carried out at 15 locations within the study area at time intervals of forenoon (9:30 – 10:30 AM), noon (12:30-1:30 PM) and afternoon (4:30-5:30 PM) for 5 days of the week (working days). Using GIS tool observed noise levels were interpolated by Inverse Distance Weighted (IDW) method and graphical plots were prepared for different time intervals.
 Results: Noise Levels were found to be between 46 dBA to 72.08 dBA during our study. Sources contributing to higher levels of noise in the premises were traffic, honking of trains followed by students themselves. On comparing the finding with Central Pollution Control Board, New Delhi, India (CPCB) standards all the locations recorded higher noise levels than the prescribed limits.
 Conclusion: Based on our finding, mitigating approaches like: plantation of trees, construction of noise barriers, proper parking area, restricting high speed of vehicles etc. were suggested for making a healthy learning environment.

Temporary hydraulic barriers using organic gel for enhanced aquifer remediation during groundwater flushing: Bench-scale experiments

This study presents the use of organic gel-forming material for the construction of hydraulic barriers in aquifer, which can be easily removed after use. Experiments on the performance of the temporary hydraulic barrier during NAPL removal (aquifer flushing) were also conducted. An aqueous solution of sodium alginate was injected into the horizontally oriented, 2-dimensional flow chamber packed with sand, followed by gelation using a calcium solution. The alginate gel formed in the porous media produced a circular shape barrier (24 cm diameter, 1.3 cm thickness) that was successfully removed using sodium bicarbonate solution (1.0 M) in 72 h, whereas the gel was stable for 7 days during simulated groundwater flushing at the same flow rate as the sodium bicarbonate solution. When circular hydraulic barriers (12 cm diameter each, 14 cm apart) were set on either side of the NAPL (n-hexane and PCE mixture)-contaminated zone, the increased water flux during water flushing resulted in significantly increased PCE removal by almost 108%. When a surfactant solution (sodium dodecyl sulfate, 0.037%) was applied, the influenced groundwater flow controlled by hydraulic barriers on the NAPL removal was amplified by 196% removal.

Accelerated performance recovery of anaerobic granular sludge after temperature shock: Rapid construction of protective barriers (EPS) to optimize microbial community composition base on quorum sensing

Poor temperature shock resistance of anaerobic granular sludge (AnGS) is one of its main disadvantages. In this study, enhancing the temperature shock resistance of AnGS by regulating quorum sensing (QS) based on the exogenous addition of N-acyl homoserine lactones (AHLs) was investigated, and the regulatory mechanism of AHLs-mediated QS based on extracellular polymeric substances (EPS) action in AnGS was revealed. The results indicated that adding 10 μM AHLs significantly enhanced the COD removal (increased by 9.3 ± 1.2%) and specific methanogenic activity (increased by 15.2 ± 3.6%) of AnGS after temperature shock, and the recovery time was reduced by 4 days. The sludge breakage and particle size reduction induced by temperature shock were attenuated by AHLs-mediated QS. Meanwhile, exogenous AHLs increased EPS concentration and the number of hydrophobic functional groups in AnGS. The addition of 10 μM AHLs reduced the ratio of Firmicutes to Bacteroidota (decreased by 0.17 ± 0.01), leading to higher microbial community stability. The enrichment of major functional bacteria (Bacteroidota, Desulfobacterota and Firmicutes) and hydrogenotrophic methanogens (Methanothermobacter and Methanobacterium) was promoted by 10 μM AHLs. The increased EPS induced by AHLs provided the protection for microbial community optimization, leading to the rapid recovery of the temperature-shocked AnGS performance. This study provided a new comprehensive insight into the regulatory mechanisms of AHLs-mediated QS in AnGS.

Predicting the hydraulic conductivity of compacted soil barriers in landfills using machine learning techniques

Machine learning models (MLMs) were developed to predict saturated hydraulic conductivity of compacted soil barriers and help to identify appropriate soils for the construction of landfill liners and covers. Data from hydraulic conductivity tests on compacted soil barriers were collected from the literature and compiled into a database for MLM construction. The database contains 329 records of hydraulic conductivity tests associated with 12 selected impact factors covering physical properties, compaction efforts, and hydration and mineralogy behaviors of compacted soil barriers. Three machine learning algorithms (random forest, gradient boosting decision tree, and neural network) were used to develop MLMs, and a statistical technique (multiple linear regression) was used to compare the precision of predictions with the MLMs. Results from this study showed that the random forest model provided the best prediction of the hydraulic conductivity of compacted soil barriers, with 100% of predicted hydraulic conductivity within 100-time differences to measured hydraulic conductivity and 93% within 10-time differences. Feature importance analysis showed that void ratio after compaction, fines content, specific gravity, degree of saturation after compaction, and plasticity index of soils are the top-five factors (in descending order) that influence the hydraulic conductivity of compacted soil barriers and are recommended for a precise prediction. Three predictive MLMs were created for industries as simple tools to screen the soils prior to the construction of compacted soil barriers in landfill liners and covers.

Geomorphological change in rivers: research approaches, results and challenges

Although rivers are inherently dynamic systems that are susceptible to change, human impact on rivers in the last century is considered to have been so significant that it has caused an unprecedented intensity of geomorphological change in river channels and floodplains. As these changes often lead to deterioration of ecological conditions as well as increased flood risks, the approach to river management has changed over the past twenty years. There is an increasing emphasis on a holistic approach based on the understanding of river system processes, for which studies of geomorphological change in rivers represent a very important source of information. The aim of this review is to present the basic methods used in studies of geomorphological change in rivers, including the spatio-hierarchical delineation of the river system, data sources, and the most commonly analysed geomorphological characteristics and factors of change. The results of previous research are presented for the period of the last 150 years. The most important geomorphological changes include channel narrowing, incision, and reduction in the complexity of fluvial landforms and processes due to channelization and the construction of numerous barriers that disrupt the connectivity in water flow and sediment transport. Explaining the cumulative impacts and predicting future changes are the major research challenges. These challenges are related to the complexity of the river system, i.e. a large number of causal factors, connections, and interactions in the river system, and to the nonlinearity of the evolutionary trajectory of changes in rivers.

УСТАНОВЛЕНИЕ ФАКТОРОВ, СПОСОБСТВУЮЩИХ ПОЯВЛЕНИЮ И ПОВТОРНОМУ ВОЗНИКНОВЕНИЮ БРУЦЕЛЛЕЗА КРУПНОГО РОГАТОГО СКОТА НА ТЕРРИТОРИИ САРАТОВСКОЙ ОБЛАСТИ

The aim of the study was to identify factors that contribute to the emergence and re-emergence of brucellosis in cattle in the Saratov region. Conducted epizootological analysis for the period from 2018 to 2022. made it possible to identify the main factors contributing to the functioning of the infectious system of brucellosis in the population of cattle in newly emerging, active and fading epizootic foci in the Saratov region. In the Saratov region, there are a number of areas where brucellosis is recorded much more often and is of a stationary nature. First of all, in the south-eastern part of the region, which is associated with an uncontrolled veterinary service, the importation of patients with brucellosis and animals infected with brucella from the nearby West Kazakhstan region of the Republic of Kazakhstan (RK), as well as the Republic of Dagestan of the Russian Federation, where brucellosis is also quite common . Another problem is that in the border areas of the Republic of Kazakhstan, many farm animals are grazing, which, when grazing in the summer, cross the border into the Saratov region, contact with the animals of our region, which also contributes to the emergence and spread of the disease. Another factor is the concealment from accounting of newly imported livestock and nascent young animals that are not subjected to serological tests for brucellosis. The fourth factor is that the livestock detected by laboratory tests, positively reacting to brucellosis, or is not sent to a specialized meat processing plant for slaughter in a timely manner. The fifth factor is that the methods used for serological diagnostics: agglutination reaction (RA) and complement fixation reaction (CFR) due to low sensitivity do not allow timely detection of animals infected with Brucella. The sixth factor is that the vaccine from Brucella abortus strain No. 82 used in disadvantaged areas of the region does not meet modern requirements. The seventh factor is that brucellosis is mainly recorded in small and individual farms, where there are difficulties in carrying out veterinary and sanitary measures, in particular, in the construction of disinfection barriers and disinfection mats, and in general, disinfection.

Опытная демонстрация гидроизоляционных свойств барьерных глинистых материалов

The article presents research data visually demonstrating the behavior of barrier clay materials with different mineral compositions when interacting with water. It shows that bentonite clays have higher waterproofing capacity: increased portion of kaolin in the mixture (decreased portion of montmorillonite) yields in a decreased waterproofing capacity of clay materials. It can be concluded that the addition of kaolinite to bentonite has negative effect on the waterproofing capacity of clay materials used in the engineered safety barriers construction.

ASSESSMENT OF THE IRRIGATION WEIR REMOVAL IN THE ENGURI RIVER

Background: Dams are one of the biggest threats to aquatic biodiversity. They restrict the movement of migratory fish. The construction of barriers can cause the complete extinction of some species from the rivers. When a dam can no longer perform its function or research will determine the need to demolish it, dams are often removed. In the lower part of the Enguri River, Georgia, an irrigation weir is currently non-functional. Aims: This research aims to prove the need to demolish the dam construction on the 44th km of the Enguri River, as it negatively impacts biodiversity and creates an artificial barrier in the river. Methods: Visual inspection was used as a method to assess the morphology and habitat of the dam where it is located. The conversation method was used with Engurhesi LTD representatives to understand the current function of the dam. The Questions were related to the current function of the dam. Results: Based on the conservation with Engurhesi LTD representatives, the study has shown that there is no reason that an irrigation weir might be left in its current state on the Enguri River. Based on the studies, the damage to biodiversity is real and disturbing. Discussion: The irrigation weir on the Enguri River was left untended because of the construction of the Enguri dam. Currently, there is no reason to divert the river Enguri with the help of an irrigation weir as there is no excess water in this river. Conclusions: In conclusion, it can be said that it is necessary to remove the irrigation weir on the Enguri River to restore habitat and mitigate the threats to biodiversity.

Submarine groundwater discharge in response to the construction of subsurface physical barriers in coastal aquifers

Submarine groundwater discharge (SGD) is an important component of the local and regional hydrologic cycles, affecting coastal water quality and ecology. However, the influence of subsurface physical barriers widely built in coastal aquifers for seawater intrusion control has not yet been fully understood with respect to the downstream SGD. In this study, we used both laboratory experiments and numerical simulations to quantify the contribution of subsurface physical barriers to the fresh and saline SGD fluxes. Different types of physical barriers, including cutoff wall and subsurface dam, were examined with various structures (e.g., barrier location, height, or penetration depth). The results demonstrated that subsurface physical barriers with different structures resulted in various changes in the location of the freshwater discharge at the aquifer-sea interface, e.g., the discharge location shifted seaward as the cutoff wall moved inland. The water exchange across the aquifer-sea interface was closely related to the structure of subsurface physical barriers. With the increase in the height of subsurface dam or the increase in the depth of cutoff wall, the fresh and saline SGD fluxes revealed a decreasing trend. Generally, the presence of a physical barrier hindered the hydraulic connection between the upstream and downstream aquifers, and the SGD fluxes were reduced compared to those without any barrier. For cutoff walls, the change in wall depths led to decreases in tide-induced saltwater circulation of 25%–33%, density-driven saltwater circulation of 10%–30%, fresh groundwater discharge of 17%–60%, and the total efflux of 18%–36%. Within the effective height range of the subsurface dam, fresh and saline SGD fluxes peaked at the minimum effective height. These findings provide a general framework for the prediction and monitoring of SGD behavior in coastal aquifers where subsurface physical barriers are intended or have been constructed.

River fragmentation and barrier impacts on fishes have been greatly underestimated in the upper Mekong River

River barriers reduce river connectivity and lead to fragmentation of fish habitats, which can result in decline or even extinction of aquatic biota, including fish populations. In the Mekong basin, previous studies have mainly focused on the impacts of large dams but ignored the impacts of small-scale barriers, or drew conclusions from incomplete barrier databases, potentially leading to research biases. To test the completeness of existing databases and to evaluate the catchment-scale fragmentation level, a detailed investigation of river barriers for the whole Upper Mekong (Lancang catchment) was performed, by conducting visual interpretation of high-resolution remotely sensed images. Then, a complete catchment-scale barrier database was created for the first time. By comparing our barrier database with existing databases, this study indicates that 93.7% of river barriers were absent from the existing database, including 75% of dams and 99.5% of small barriers. Barrier density and dendritic connectivity index (DCID and DCIP) were used to measure channel fragmentation within the catchment. Overall, 50.5% of sub-catchments contained river barriers. The Middle region is the most fragmented area within the Lancang catchment, with a median [quartiles] barrier density of 5.34 [0.70–9.67] per 100 km, DCIP value of 49.50 [21.50–90.00] and DCID value of 38.50 [9.00–92.25]. Furthermore, since 2010, distribution ranges of two representative fish species Schizothorax lissolabiatus (a rheophilic cyprinid) and Bagarius yarrelli (a large catfish) have reduced by 19.2% and 32.8% respectively, probably due in part to the construction of river barriers. Our findings indicate that small-scale barriers, in particular weirs and also small dams are the main reason for habitat fragmentation in the Lancang and must be considered alongside large dams in water management and biodiversity conservation within the Mekong.

Urban encroachment in ecologically sensitive areas: drivers, impediments and consequences

The drivers and consequences of unregulated urban expansion processes in Accra, Ghana, are examined together with the associated encroachment upon ecologically sensitive areas in the city’s rapidly growing periphery. Three sites are considered which attracted settlers from vastly different economic segments of the urban population from the 2000s and onwards. A combination of geographical information system (GIS)-based analysis, evidence from a recent household survey, insights from a range of key informant interviews and field observations provide evidence for the dynamics of urban expansion and settlement consolidation. These dynamics wield significant pressure on ecologically sensitive areas, <em>e.g.</em> wetlands, riparian zones and coastal lagoons, which are transformed into housing development through drainage, landfilling, channelling of streams and construction of barriers. Encroachment upon ecologically sensitive areas is associated with intensifying flood hazards. Key impediments are identified for the preservation of ecologically sensitive areas within the specific urban governance context of Accra. Encroachment is not necessarily driven by poverty or low income; it occurs for several socio-economic situations. Governance and enforcement in planning need improvement. Such insights must inform efforts to promote more sustainable trajectories of urban expansion, allowing cities to accommodate rapidly growing populations while preserving ecologically sensitive areas and benefiting from crucial ecosystem services. <strong><em><br /></em></strong> <strong><em>Policy relevance</em></strong> Critical impediments exist in planning urban expansion. Insights are provided on why ecologically sensitive areas are not sufficiently protected from urban encroachment. These include the intricacies of regulating land transactions in rural and peri-urban areas before incorporation into the built-up area of the city, the ambivalent and overlapping land administration systems, the strong incentives for traditional authorities to commercialise marginal land, the unfeasibility of policing permanent structures, and the lack of cooperation and coordination among local government entities concerning the management of urban watersheds. Within the urban governance context of Accra, encroachment upon ecologically sensitive areas constitutes a ‘wicked’ planning problem that defies rational, technical solutions and which is fraught with multi-causality, multiple perspectives and diverging interests. Insights into these complexities must inform efforts to promote more sustainable trajectories of urban expansion.

The Temporal-Spatial Variation and the Cause Analysis of the Thermokarst Lakes Along the Qinghai-Tibet Highway in Recent 30 Years

As the climate changed, the Qinghai-Tibetan Plateau (QTP) has been experiencing rapid permafrost degradation in the past decades. One of the most remarkable characteristics is the formation of thermokarst lakes. Based on the Google Earth Engine platform (GEE), the distribution of thermokarst lakes along the Qinghai-Tibet Highway (QTH) in recent 30 years (1991-2020) are examined, and the environmental factors affecting the distribution of thermokarst lakes are investigated, combined with field monitoring and Landsat data. Both the number and area of thermokarst lakes along QTH show a trend of decreasing - increasing - rapidly increasing - decreasing. The area of thermokarst lakes increased from 107.14 km² in 1991 to 184.92 km² in 2020. In 2018, the density of thermokarst lakes along the Qinghai-Tibet Highway was 14.4 /100km², which is generally high over QTP. The changes in the number and area of the thermokarst lakes on the QTP were significantly positively correlated with the annual mean temperature (p <0.05), while weakly positively correlated with the annual mean precipitation, indicating that the number and area variations of the thermokarst lakes on the QTP were strongly affected by temperature than precipitation. The study on QTP thermokarst lakes provides an investigation of the impact of climate change on the ecology and environment of permafrost regions, background research for the construction of QTH, and further serve the construction of ecological safety barrier in China.

Institutionalising the Exception: Homeland Security Section 102(c) Waivers and the Construction of Border Barriers

ABSTRACT To expedite the construction of barriers along the border with Mexico, U.S. Secretaries of Homeland Security have waived an extensive array of laws since 2005 when authority for such actions was first delegated to that position as part of the REAL ID Act. This paper contextualises the political origins of what is referred to as Section 102(c) waiver authority, shows how these waivers are used to dramatically expand border barrier construction, and reviews legal challenges. In doing so, it connects the use of waivers in governance as viewed through the study of law with the theoretical prominence of Agamben in the discipline of geography. By examining the specific ways in which these legal practices and their geographic expression have institutionalised a state of exception that pushes the boundary of legal acceptability, we arrive at a more transdisciplinary understanding of the role of states of exception as a tool of governance.

Relationship of spirituality, health engagement, health belief and attitudes toward acceptance and willingness to pay for a COVID-19 vaccine.

To explore the wider determinant factor of citizens' spirituality, health engagement, health belief model, and attitudes towards vaccines toward acceptance and willingness to pay for a Coronavirus disease 2019 (COVID-19) vaccination. A community-based cross-sectional online investigation with convenience sampling was utilized to recruit 1423 citizens from 18 districts across Indonesia between December 14, 2020 and January 17, 2021. Descriptive statistics, One-way analysis of variance, Pearson correlation, Independent t-tests, and multiple linear regression were examined. Spirituality, health engagement and attitude toward vaccines, as well as health beliefs constructs (all scores of perceived benefits and barriers) were significant key factors of acceptance of vaccines. Interestingly, the spirituality, attitude toward vaccine, and health beliefs constructs including perceived susceptibility, and benefits indicated a significantly higher willingness. Results demonstrated the utility of spirituality, health engagement, health belief model, and attitudes towards vaccines in understanding acceptance and willingness to pay for a vaccine. Specifically, a key obstacle to the acceptance of and willingness to pay COVID-19 vaccination included a high score of the perceived barrier construct. Moreover, the acceptance of and willingness to pay could be impaired by worries about the side-effects of a COVID-19 vaccination.

From Small-Gain Theory to Compositional Construction of Barrier Certificates for Large-Scale Stochastic Systems

This article is concerned with a compositional approach for the construction of control barrier certificates for large-scale interconnected stochastic systems while synthesizing hybrid controllers against high-level logic properties. Our proposed methodology involves decomposition of interconnected systems into smaller subsystems and leverages the notion of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">control</i> <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sub-barrier certificates</i> of subsystems, enabling one to construct control barrier certificates of interconnected systems by employing some <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\max$</tex-math></inline-formula> -type small-gain conditions. The main goal is to synthesize hybrid controllers enforcing complex logic properties, including the ones represented by the accepting language of deterministic finite automata, while providing probabilistic guarantees on the satisfaction of given specifications in bounded-time horizons. To do so, we propose a systematic approach to first decompose high-level specifications into simple reachability tasks by utilizing automata corresponding to the complement of specifications. We then construct control sub-barrier certificates and synthesize local controllers for those simpler tasks and combine them to obtain a hybrid controller that ensures satisfaction of the complex specification with some lower bound on the probability of satisfaction. We finally apply our proposed techniques to a fully-interconnected Kuramoto network composed of 100 nonlinear oscillators.

Viscosity method for random homogenization of fully nonlinear elliptic equations with highly oscillating obstacles

Abstract In this article, we establish a viscosity method for random homogenization of an obstacle problem with nondivergence structure. We study the asymptotic behavior of the viscosity solution u ε {u}_{\varepsilon } of fully nonlinear equations in a perforated domain with the stationary ergodic condition. By capturing the behavior of the homogeneous solution, analyzing the characters of the corresponding obstacle problem, and finding the capacity-like quantity through the construction of appropriate barriers, we prove that the limit profile u u of u ε {u}_{\varepsilon } satisfies a homogenized equation without obstacles.

Determining Factors For Social and Environmental Practices of Corporate Responsibility in Mozambique

Purpose: This study analyzes the main factors that determine the adoption of social and environmental practices in companies operating in Mozambique. To this end, it analyzes the perception of managers about the pressure, motivation and barriers they face for these practices. Theoretical framework: Corporate Social Responsibility (CSR) is based on legitimacy, stakeholder and institutional theories. The stakeholder theory has two variants: one that concerns the attention to all stakeholders in the activities of the organization; the second is understood in a strictly organization-centered manner and relates to empirical responsibility. The latter coincides with the concept of legitimacy theory where they try to ensure that their activities are perceived as being legitimate. In institutional theory, the dependence of an organization creates isomorphisms of structure, climate and behavioral focus. Method/design/approach: The data were collected through a stratified sampling survey according to the size and nature of the activities, using Likert type questions. Constructs of Pressure, Internal Motivation and Barriers to CSR practices were assessed, as well as compliance with social and environmental practices. A number of 227 representative responses of Mozambican business fabric were obtained. To analyze the data and test the conceptual model presented, we used the PLS (Partial Least Squares) methodology. Results and conclusion:. The results show that there is little pressure from stakeholders and society in general, low motivation of the agents responsible for practicing social and environmental actions and that they recognize that barriers exist, but do not have a significant effect on the decision to adopt CSR practices. It was also found that in the CSR analysis, social practices should be seen separately from environmental practices. Research implications: The study argues that managers consider the multi-factors involved in CSR. It also points to important contributions to the definition of economic policies and institutional designs, particularly in developing countries, to leverage CSR practices. Originality/value: This study contributes to the literature by demonstrating that, although there are positive conditions, negative factors (barriers) in the determination of social and environmental practices should not be neglected. Additionally, the conclusions presented differ significantly from the results obtained in geographies of developed countries, thus contributing to the understanding of the determining factors in African countries, which has been less studied, and in particular in Mozambique, to which we contribute in a pioneering way.

Bulli Pass Landslide Risk Management Part 1 - Hazard Assessment

The Princes Highway along Bulli Pass is a narrow, heavily trafficked two lane section of the Princes Highway that traverses steep slopes on a grade of 9H:1V on the Illawarra Escarpment, about 11 km north of Wollongong, and 75 km south of Sydney in New South Wales (NSW), Australia. It is an important arterial road for the northern suburbs of Wollongong, connecting Mt Ousley Road (M1 Princes Motorway) at the crest of the escarpment to the suburb of Thirroul on the coastal plain at the base of the escarpment. Bulli Pass has a long history of landslide and rockfall events, some of which were reported as early as 1890. One of the most significant of these events occurred on 17 August 1998 during a 1 in 100 year rainfall event. The 1998 landslide event comprised approximately 38 debris flows and slides and numerous rockfalls which partially inundated a number of cars and trapped about 15 cars on the pass. More recently, in early 2015, a small rockfall penetrated the windscreen of a car travelling up the pass. Transport for New South Wales (TfNSW) commissioned an investigation into slope instability hazards affecting the road in late 2011. This was followed in 2015 by a Risk Mitigation Options study and the detailed design of risk mitigation works in 2016. This paper provides an overview of the methods used to investigate hazards and assess risk at the site over a five year period. This has included research into the landslide history, geomorphological mapping, acquisition and review of airborne laser scanning (ALS) data, review of rainfall data and the development of a landslide volume frequency model. The development of this model allowed hazards to be readily communicated and risks to be assessed. The actual design and construction of the Shallow Landslide Barriers and the Debris Flow Barriers that followed on from these assessments will be discussed in a subsequent companion paper.

Clay and carbon materials-based engineered barriers for technetium immobilization

Immobilization of long-lived 99Tc is one of the most complicated tasks faced during disposal of radioactive waste. Bentonite clays, which are common components used for construction of engineered barriers are not capable of preventing migration of highly soluble oxidized technetium forms. Modification of bentonite clay materials with natural and industrial coals of various genesis, added in amount of 5 mass %, was carried out as part of this research. The anthracite from Omsukchan coal cluster, coke of Kuznetsk basin and activated carbons of AG-3 and CAU marks have demonstrated high ability to immobilize technetium under oxidizing conditions with values of partition coefficient exceeding 103 ml/g. The resulting composite materials are characterized by low water permeability (Kp < 1–5·10−11 m/s at a dry density of 1.1–1.2 g/cm3), which is mandatory for engineered barriers. Dispersed materials are easy-flowing (ff > 4), which allows the construction of clay barriers by dry, cavity-free backfilling. Quantitative immobilization of technetium occurs during the first day of interaction, with strongly-bonded forms accounting for over 90% of all technetium in the barrier material.