Sulphide soil is an organic soil characterised by high water content and poor geotechnical properties. When excavated, it oxidises and becomes an environmental hazard due to leached metals and acid drain. To avoid excavation, methods for utilizing more sulphide soil as a subgrade material are being developed. However, precise characterisation of sulphide soil is challenging, as its inherent properties make it prone to sample disturbance, introducing large scatter into geotechnical test results. To minimise the scatter in laboratory test results, a portion of the characterisation could be based on reconstituted samples. This study explores the applicability of the slurry deposition method to produce homogeneous, repeatable and representative sulphide soil samples. The reconstituted samples were assessed by comparing their initial index properties and triaxial behaviour against those of the intact samples. The index properties of the tested reconstituted samples precisely and accurately matched the average results of the intact samples. The undrained triaxial behaviour and derived critical state line of the reconstituted samples and the intact samples were found to be comparable. Neither type of sample reached critical state in drained triaxial testing. In conclusion, this study suggests that the slurry deposition method is suitable for reconstituting sulphide soil samples.

Understanding the thermal regime of road embankments in cold climates during winter is essential for efficient road design and accurate estimation of maintenance frequencies to reduce freeze-induced damage. In response to the challenging climate conditions in northern Sweden, an experimental field setup was designed to assess the thermal impact of culverts and accumulated snow in ditches on the thermal regime of road embankments during a winter season. This study provides detailed information on the experimental setup, highlights potential challenges from installation phase to data acquisition, and addresses measurement errors. Methods to ensure accuracy and obtain reliable data are also presented. Additionally, some of the obtained measurement results are included in this paper. The results show that snow impacts the thermal regime of the embankment from the onset of accumulation in the ditch, when the snow cover is still thin, until it reaches a depth of 65 cm. Beyond this depth, the soil beneath the snow remains almost unfrozen throughout the winter season. Additionally, the temperature distribution measurements within the embankment indicate that freezing progresses faster near the culvert compared to the rest of the embankment. However, once the culvert ends are insulated by snow cover, the frost depth in the soil near the culvert does not increase significantly, while the rest of the road continues to freeze gradually to greater depths throughout the winter season. The measurement results presented in this study provide researchers with a reliable dataset for validating numerical models in related research areas simulating cold-climate conditions. Additionally, these results enhance the understanding of the thermal regime of road embankments in typical cold climates and offer valuable insights for planning road maintenance and construction in such regions. Furthermore, this study provides essential information for researchers aiming to design and optimize experimental measurement setups in similar investigations.

In Sweden, the most common remediation measure to stop acid rock drainage (ARD) formation from mine waste is to apply a multi-layer cover on top of the waste deposit. The access to suitable cover-materials is, however, limited, creating a driving force for alternative solutions. The recycling of an industrial residue for this purpose is beneficial for the industry where the residue is generated, the mining industry using the residue, and the society’s strive for end-of-waste. Green liquor dregs (GLD), a residue from pulp production, is an example of an industrial residue that has the potential to improve the sealing properties of a till. The use of a GLD-till mixture for the construction of a sealing layer in mine waste covers is one alternative to the wellused bentonite amendment to a permeable till. A few trials on using GLD-amended till have been made at demonstrational scale, but this study is the first to evaluate a sealing layer of a sulphidic mine waste cover consisting of GLD-amended till, monitored for four years. The results are compared to a traditional bentoniteamended till cover, analysing soil water content and oxygen concentrations. In addition, two methods of instrument installation (pits and monitoring wells) were evaluated. The monitoring of the soil water content in the sealing layers indicate saturation, or close to saturation, in both materials. This implies a successfully functioning sealing layer that minimises oxygen diffusion to the waste rock underneath. More monitoring is needed to conclude on the long-term performance of both types of sealing layers, i.e. bentonite-amended till and GLD-amended till. The findings in this and a previous study suggest that pits are recommended as an installation method if horizontal installation of instruments is possible. However, this study also concludes that the current great variation in GLD, especially its water content, makes it difficult to use compared to commercial, more homogenic, products.

Strains at the bottom of a large-scale experimental embankment dam were measured by fibre optics. The strains were measured in four sections, orthogonal to the dam axis. The fibre optic set up was operational after finalising the dam construction. The measurements were conducted continuously during the impoundment and later during the operation with an upstream water level of a maximum of 3.5 m. Based on the measurements, the post-construction behaviour of the dam was observed, indicating settlements. The foundation of the dam is inclined, which was captured by the measurements, with indications of more shear stresses developing at the downstream side. Variations of strains in the different dam zones were observed. The impoundment is causing most of the strain development in the dam. The strains develop further over time after the reservoir is at its maximum level, indicating a transient process is in place.

In 2019, Vattenfall AB together with several researchers, built an experimental embankment dam in Älvkarleby, Sweden. The dam was a four metres high small-scale conventional rockfill dam. The design and construction methods followed the Swedish dam safety guidelines for conventional dams. The dam was zoned, with a core made of glacial till, surrounded by fine and coarse filter zones and shoulder material. The dam was built and finalized in November 2019. Pore pressure, seepage, deformations and strains have been monitored in the dam. The impoundment of the dam was conducted in the first half of 2020, thereafter the water level in the reservoir was kept constant until early 2022. Then five cycles of emptying and filling up of the reservoir were conducted to evaluate the effects on the cyclic conditions of the embankment dam. In this contribution, the effects of varying reservoir levels on the dam body are assessed, based on the results from the monitoring of the pore pressures. Varying reservoir levels in hydropower dams, in a larger extent is usual today due to the new more flexible energy market, and are thus relevant for existing dams in the green transition.

Polycarbonate plastics containing bisphenol A (BPA) used to manufacture drinking water bottles. Kurdistan region in northern Iraq is a developed area with increased pollution from plastic bottles. Trace amounts of BPA have been detected in bottled water samples. The absorption of BPA was measured with HPLC using a vertical cultivation system with Bulbs of the Allium Cepa plant planted in these plastic bottles with monitored growth. Vertical cultivation was found to have a low level of BPA in the plant cells, making it a safe cultivation method under specific climate conditions. The mean concentration of BPA in vertical cultivation is 0.19 ug/ml (3.8 ng for a 20 uL injection), and the Limit of Quantification (LOQ) is 0.63 ug/ml (12.7 ng for 20 uL injection). While Scanning Electron Microscope (SEM) shows that the concentrations are relatively low in water samples stored at room temperature compared to those exposed to direct sunlight (40°C) and water bottle samples stored at (-4°C), The correlation coefficients were found to be good (0.9992). SEM is used for plastic bottle samples stored at different temperatures. The images identify compound decay and explore the morphology of BPA in manufactured plastic materials.

The mining industry has experienced rapid growth, leading to the accumulation of substantial mine waste, commonly referred to as tailings. Tailings are typically stored in tailings storage facilities, conventionally consisting of an impoundment surrounded by tailings dams. The construction of tailings dams can involve various methods, with the upstream method being commonly used in the industry. It is crucial to comprehend the long-term mechanical and geochemical behavior of deposited tailings to ensure the safety of upstream constructed tailings dams. The mineral composition, particle size distribution, and particle shape all affect the susceptibility to particle breakage or physical alternation. Therefore, there is an interest in understanding how grain size and grain shape relate to mineral composition and potential particle breakage to ensure the understanding of the long-term mechanical behavior. This study focuses on characterizing deposited tailings from various depths and investigates the impact of increased vertical stress on tailings, particularly examining the potential for crushing effects. The findings highlight the importance of considering these factors for a comprehensive understanding of tailings behavior and their implications for the long-term safety of tailings dams.

Frost-related damages around culverts are a common problem for roads and railways built on seasonally frozen ground. Culverts create altered thermal conditions in the embankment section where they are installed, leading to deeper frost penetration around the culverts compared to the rest of the road. However, estimating the depth of frost penetration and consequential heave is difficult due to the complex thermal conditions inside culverts, which depend on various factors. To monitor the influence of culverts on the surrounding soil and assess the effect of temperature distribution inside the culvert on frost penetration in the embankment, temperatures were measured inside a 0.6 m diameter culvert and in the soil 0.30 m from the culvert in northern Sweden during the winter of 2023. Control measurements were also performed in a road section without a culvert. Temperatures were recorded in seven locations in the embankment at depths ranging from 0.1 m to 2.55 m. Effect of the temperature distribution inside the culvert on frost penetration in the embankment is assessed. The results of this study could help in the design and management of culverts in cold climates and improve our understanding of the thermal conditions around culverts. This field study is part of a larger project where collected data will be used to verify numerical models, enabling assessment of the effect of culverts of any size on temperature distribution.

Ground thermal regime in cold regions is influenced by seasonal snow cover, which acts as an insulating layer influencing the heat transfer between the atmosphere and the underlying soil. The thermal properties of the snow change with different environmental conditions, playing a crucial role to determine the thermal state of the sub-surface soil. Previous research in this field have faced challenges to accurately characterize thermal properties of seasonal snowpacks under varying spatial and meteorological conditions. To address this issue, two experimental field setups were constructed in Luleå, Sweden, to observe the temperature distribution of the snowpack and the ground sub-surface soil. The first experiment studied a naturally accumulated, undisturbed snowpack. The second experiment was conducted on a roadside ditch where the snowpack consists of a combination of natural accumulated snow and plowed snow from the adjacent road. In this research, heat transfer processes at both field sites were monitored over a winter season each to better understand the complex relationship between snow cover properties and sub-surface thermal regime. Furthermore, thermal conductivity of a basal layer in each snowpack was calculated over a time period, based on the field measurements. The results showed that the history of snow deposition, meteorological conditions, and changes in soil moisture impact the metamorphism process within the snowpack, thereby altering the structure of the layers of snowpack and its influence on the thermal regime of the sub-surface soil. The findings of this research have important applications in various sectors, from mining to road maintenance and agriculture.