Underground Sites Research Articles

Behavior of rare earth elements in an aquifer perturbed by CO2 injection: Environmental implications

Three cubic-meters of CO2-saturated water was injected into a subsurface fractured aquifer in a post-mined area, using a push-pull test protocol. Groundwater samples were collected before and after CO2-injection to quantify geochemical changes. CO2-injection initially reduced the pH of water from 7.3 to 5.7, led to the enrichment of major ions (Ca2+, Mg2+, and alkalinity), and dissolved trace metals (including Fe, Mn, As, and Zn) in the groundwater. Rare earth elements (REE) and yttrium concentrations were also measured in these samples before and after CO2 perturbation, to evaluate their behavior. An enrichment of total Y plus REE (REY) occurred. REY fractionation was observed with higher heavy REE (HREE) enrichment compared to light REE (LREE), and significant variations in La/Yb and Y/Ho ratios were observed following CO2 perturbation. Enrichment by a factor of three was observed for Y, Lu, and Tm, and by nearly one order of magnitude for Dy and Yb. A geochemical model was used to evaluate the amount of REE aqueous ions complexed throughout the experiment. Modeling of the results showed that speciation of dissolved REE with carbonate, along with desorption from iron oxyhydroxide surface were the main factors controlling REE behavior. This study increases an understanding of dissolved REE behavior in the environment, and the potential use for applying iron oxides for REE recovery from mine drainages. Furthermore, the description of REE fractionation patterns may assist in surveying CO2 geological storage sites, surveying underground waste disposal sites, and for understanding the formation of ore deposits and fluid inclusions in geological formations.

Evaluating the Radiation Status of the Environment on the Underground Nuclear Explosion Site Code-Named Tavda

This paper analyzes the radiation status of environmental components on the underground nuclear explosion site codenamed Tavda, which is located in the Nizhnetavdinsky District of Tyumen Oblast. This underground nuclear explosion occurred in 1967 and was part of the Program #7 Nuclear Explosions for the National Economy; it is currently one of the sources of radiation pollution in its environment. The authors hereof present the analysis of technogenic radionuclide contamination of soils in the explosion epicenter as well as within 500 meters thereof, which analysis takes into account the horizontal and vertical migration of radionuclides, and the contamination of grassy vegetation with strontium-90 and caesium-137 (measurements were taken at 100 m intervals).We have found out that the radiation burden is essentially a function of strontium-90 content in the soil. Maximum density of strontium-90 and caesium-137 contamination is observed in deeper soil layers. Technogenic radionuclide contamination is present in naturally growing grass on the Tavda site due to a high concentration of strontium-90 with a mean specific radionuclide activity of 288.33 Bq/kg, while the maximum permissible concentration of this element in natural hay is 180 Bq/kg. The concentration of caesium-137 in collected samples was not found to be in excess of the permissible concentrations.

Preliminary assessment of underground hydrogen storage sites in Ontario, Canada

The replacement of coal-fired power plants with increasing proportions of renewable and nuclear energies in the province of Ontario highlights the need to balance seasonal energy demands. This can be achieved through power-to-gas technology, where excess energy is used to generate hydrogen gas through electrolysis, and the generation is coupled with underground hydrogen storage. This article presents a preliminary assessment regarding the potential for underground hydrogen storage in geological formations including salt and hard rock caverns, depleted oil and gas fields, and saline aquifers in Ontario, highlighting potential locations where future storage could be feasible. Southern Ontario presents many potential storage options, including Silurian bedded salts, depleted Ordovician natural gas reservoirs, saline aquifers in Cambrian sandstone and hard rock caverns in argillaceous limestones. Hard rock caverns in Precambrian crystalline rocks of the Canadian Shield are also discussed, in addition to the potential for the use of lined rock caverns. This work aims to provide a basis for further research regarding the appropriate location of underground hydrogen gas storage facilities in Ontario.

Effects of Different Penetration Patterns on a Fault during Underground Fluid Injection

At underground fluid injection sites with natural faults, understanding how to avoid the subsequent fault reactivation and induced seismicity plays a crucial role in the success of subsurface anthropogenic activities. In this work, with the objective of avoiding risky faults in site selection in the Shengli Oilfield, we investigated the faults that are usually encountered in the target demonstration zone; based on the geophysical observations of fault structures, we designed different fault tectonic scenarios to investigate the different penetration patterns of faults. We used the finite element-based numerical method to assess the influence of the effective lateral and vertical reservoir transmissivity in each fault penetration pattern. Our results indicate that when a permeable fault intersects into the target reservoir, it presents both barrier effect to reservoir transmissivity within the target reservoir and hydraulic connection between reservoirs. The effective lateral reservoir transmissivity is dominated by the barrier effect of the fault, and the effective vertical reservoir transmissivity is dominated by the hydraulic connection between reservoirs. Relatively impermeable faults with less contact with the target aquifer make higher effective lateral reservoir transmissivity and lower effective vertical reservoir transmissivity, which would mitigate the risk of caprock failure and the magnitude of the induced seismicity.

Geoecological Monitoring on the Territory of Underground Disposal Sites of Highly Mineralized Waters in Western Yakutia

The safe disposal of highly mineralized runoff in the development of indigenous diamond deposits in Western Yakutia is the most important task of ensuring a favorable geo-ecological situation in the region. Using the example of a large experimental material collected at the industrial site of the Udachninsky mining and processing plant, PJSC ALROSA, the geoecological situation in the area of underground drainage water disposal sites was assessed. Under the conditions of a complex and dynamic cryohydrogeological situation on the background of an increase in the volume of water inflow into the mine workings, the excess of the capacitive capabilities of the reservoirs of the storage tanks of the brine can lead to serious geoecological problems. Markers that identify the effects of highly mineralized water on the main abiotic components of the region's ecosystems – soil, bottom sediments and surface water – are strontium and lithium.

Muon-induced neutrons in lead and copper at shallow depth

Next generation low-background experiments require a detailed understanding of all possible radiation backgrounds. One important radiation source are muon-induced neutrons. Their production processes are up to now not fully understood. New measurements with MINIDEX (Muon-Induced Neutron Indirect Detection EXperiment) of the production of neutrons by cosmogenic muons in high-Z materials are reported. The setup is located at the Tübingen Shallow Underground Laboratory, which provides a vertical shielding depth of (13.2 ± 0.8) meter water equivalent at the setup location. Muon-induced neutrons are identified by the detection of 2.2 MeV gammas from their capture on hydrogen with high-purity germanium detectors. The experimental results were compared to Geant4 Monte Carlo predictions. The measured rate of 2.2 MeV neutron capture gammas for lead was found to be in good agreement with the Geant4 predicted rate. An external neutron yield of (7.2 -0.6+0.7) · 10−5 g−1 cm2 neutrons per tagged muon was determined for lead with the help of Geant4. For copper the measured rate was found to be a factor of 0.72 ± 0.14 lower than the Geant4 predicted rate. Using this factor an external neutron yield of (2.1 ± 0.4) · 10−5 g−1 cm2 neutrons per tagged muon was obtained for copper. An additional simulation was performed using the FLUKA Monte Carlo code. The FLUKA predicted rate of detected 2.2 MeV neutron capture gammas for lead was also found to be in good agreement with the experimental value. A detailed comparison of muon interactions and neutron production in lead for Geant4 and FLUKA revealed large discrepancies in the description of photo-nuclear and muon-nuclear inelastic scattering reactions for muon energies at shallow underground sites. These results suggest that Geant4, when used with Geant4 recommended or standard physics lists, underpredicts the neutron production in photo-nuclear inelastic scattering reactions while at the same time it overpredicts the neutron production in muon-nuclear inelastic scattering reactions.

Removal of heavy metals (Co, Cr, and Zn) during calcium\u2013aluminium\u2013silicate\u2013hydrate and trioctahedral smectite formation

Hydrated aluminosilicates were synthesized with and without aqueous heavy metals (Me), such as cobalt (Co), chromium (Cr), and zinc (Zn), by a sol–gel process at different initial molar ratios of Ca/(Si + Al) (0.6–1.6) and Me/Si (0.0–2.0), and constant Al/Si ratio (0.05) using equilibrium-approaching experiments. The chemical composition of the reactive solutions during aluminosilicate precipitation and maturation was monitored by ICP-OES. The mineralogy, nanostructure, and chemical composition of the precipitates were studied by XRD and high-resolution TEM. At Me/Si ratios ≤ 0.2, calcium–aluminium–silicate–hydrates (C–A–S–H) with a defect 14 Å tobermorite-like structure formed, whereas at a Me/Si ratio of 2.0, either trioctahedral Co- and Zn-smectite or amorphous Cr gels precipitated, independent of the initial Ca/(Si + Al) ratio used for gel synthesis. The immobilization capacities for {text{Co}}^{2 + } , {text{Cr}}^{3 + } , and {text{Zn}}^{2 + } by C–A–S–H, Cr gel, and trioctahedral smectite are 3–40 mg/g, 30–152 mg/g, and 122–141 mg/g, respectively. The immobilization mechanism of heavy metals is based on a combination of isomorphous substitution, interlayer cation exchange, surface (ad)sorption, and surface precipitation. In engineered systems, such as underground concrete structures and nuclear waste disposal sites, hydrated aluminosilicates should exhibit a high detoxication potential for aqueous heavy metals.

How worker health and safety representatives are captured and outdone by production on South African mines

In South Africa, post-apartheid, under the Mine Health and Safety Act No. 29 of 1996, workers elect health and safety representatives (HSRs). Descriptive case studies were conducted at four underground mine sites (gold, platinum and diamond) to explore the relationship between employer safety management and HSRs. A systems approach (socio-autopoiesis) is used as a metaphor for the circular/closed communication that ensured HSRs were dominated by employer interests and let down by the regulator. The stance of the employer to worker representation has not significantly changed since the managerial self-regulation prevalent in the demise of apartheid years. Given union membership is high, the capacity of HSRs to act without reference to management is uniquely compromised and presents as an anomaly in studies of worker representatives worldwide.

Prediction of pressure and temperature changes in the salt caverns of Tuz Golu underground natural gas storage site while withdrawing or injecting natural gas by numerical simulations

Tuz Golu (Salt Lake) Underground Gas Storage (UGS) Project in Turkey is being implemented. In some of salt caverns, natural gas is currently stored. While analyzing the data of Tuz Golu UGS project, it was observed that this location is appropriate for safe underground natural gas storage due to its rock salt with high purity and very low permeability. In this study, many numerical simulations for a salt cavern in Tuz Golu UGS project at different gas withdrawal and injection rates were conducted by using TOUGH + RealGasBrine simulator. According to the results of these numerical simulations, the temperature inside salt cavern reduced below 0 °C from 53 °C within 20 days at a rate of gas withdrawal of 3.33 million standard m3/day due to Joule-Thomson effect. The temperature inside salt cavern reduced below 0 °C within 25 days, 40 days, and 60 days at a rate of gas withdrawal of 2.5, 1.67, and 0.833 million standard m3, respectively. In order to avoid fracture around the walls of salt cavern, the temperature change inside salt cavern should not be higher than 30 °C. In the numerical simulations, there is no gas seepages from the salt cavern to other neighbor salt caverns, which are 600 m away owing to very low permeability of salt rock in the study area. The implication of this study is that gas withdrawal and gas injection profiles are quite important to keep the temperature inside salt caverns at an optimum range for safe natural gas storage.

Face Ventilation on a Bleederless Longwall Panel.

A ventilation study using tracer gas was conducted at a western US coal mine. The objective of the study was to evaluate the movement of longwall face air exchanges between the face and worked-out area and to document the presence or absence of face airflow pathways between these locations. The mine operator uses a bleederless longwall ventilation system with a back return and a blowing mine ventilation system. The study was conducted on an active panel and included both underground and surface monitoring sites. The study used sulfur hexafluoride (SF6) released as a slug on the longwall face and in the front of the gob inby the face. The velocity of the tracer gas movement in the gob was 0.019 m/s (3.7 fpm). The rate of movement for the overall tracer gas slug averaged about 0.0091 m/s (1.8 fpm). A separate tracer gas test initiated with the release of SF6 into the legs of the first shield showed the existence of more than one pathway of face air in the general direction from the headgate towards the tailgate corner. Maintaining adequate ventilation air on longwall faces is important for worker safety and for the dilution of methane emitted from the face and caved gob. A more detailed characterization of longwall system air and gas movement allows a mine to better assess its ventilation design for controlling gas on the face and in the gob.

Long-Term Increase in Hibernating Bats in Swedish Mines — Effect of Global Warming?

We present the result of bat winter censuses in three old mines in southern Sweden from 1980 until present (2017). The Taberg and Kleva mines, each with about 1.5 km of accessible passages, have winter populations of 517 and 132 bats, respectively (maximum counts) belonging to six species, the highest numbers known in underground sites in Sweden. Adelfors is less extensive and has fewer individuals (maximum 22). The two former sites were protected and gated in the 1980′s while the third site still has no formal protection and is subject to disturbance. Generally Daubenton's bat Myotis daubentonii and the brown long-eared bat Plecotus auritus are common species and the numbers are stable. The whiskered and Brandt's bats M. mystacinus/brandtii and Natterer's bat M. nattereri have increased significantly, while the northern bat Eptesicus nilssonii, which is relatively rare in mines generally, has shown a slight but significant decline. At the species level the population trends conform well to those of the respective species in continental Europe and the British Isles. This suggests that there is a common factor behind the population changes across Europe. Although our data are very limited, the results question some previous explanations for the observed trends, but are in line with theoretical predictions based on global warming scenarios.

Allocating Underground Dam Sites Using Remote Sensing and GIS Case Study on the Southwestern Plain of Tehran Province, Iran

Systematic planning for extraction of underground water resources using the modern techniques is an essential task for appropriate use, protection and management of these vital resources. This study aims to develop a method for determining appropriate locations for underground dam (UGD) construction with the help of geospatial and multi-criteria analysis. This study was conducted over an area of 3396 km2 located in the southwest of Tehran province. The geographic information system, remote sensing and the mathematical method of the analytical hierarchy process were used to produce a map for the five categories from very high potential areas to very low potential ones, which indicate the suitability for UGD construction. The map was produced with the input variables such as precipitation, recharge, geological situation, lineament density, slope, density of the drainage streams and depth of groundwater. The weights for each factor were assigned according to its effect on the groundwater potential, and finally, the map was produced from the spatial weight model. The map showed that the Tehran–Karaj plain has generally an average potential for constructing UGDs with an area of 1562 km2, which covers 46% of the whole study area. The results of this study and obtained maps provide the useful information that can be used by decision makers and managers in exploration and optimal management of groundwater resources.

An ardent anti-slavery tale: Narrating resistance through Chicago's Underground Railroad, 1856-present

ABSTRACTOriginally situated in a suburb, today the 1856 Gray House is a private residence and part of Chicago's Old Irving Park neighbourhood. Known for his vocal stand against slavery, John Gray was the first Republican Sheriff of Cook County (1858–1860). In the years after his death, popular narratives arose designating his home a station on the Underground Railroad. By interrogating the documentary record, results from archaeological survey and excavation, and reports from known Underground Railroad sites, this paper focuses on the way that stories of the Underground Railroad are a preferred narrative of uplift and resistance even with absent site-specific evidence for these antislavery activities.

Simulation of muon-induced neutral particle background for a shallow depth Iron Calorimeter detector

The Iron Calorimeter (ICAL) detector at the India based Neutrino Observatory (INO) is planned to be set up in an underground cavern with a rock overburden of more than 1 km. This overburden reduces the cosmic muon flux by a factor of 106 with respect to that at the sea level. In this paper, we examine the possibility of a 100 m shallow depth ICAL (SICAL) detector. The cosmic muons would have to be detected in a veto detector with an efficiency of 99.99% in order to have the same level of muon background leaking undetected through the veto detector as at the 1 km depth underground site. However, an additional background arises from interactions of cosmic muons with the rock. Since the neutral particles produced in such interactions can pass through the veto detector without any interaction, they can possibly mimic neutrino events in the ICAL. In this paper, the results of a GEANT4 based simulation study to estimate the background signals due to muon induced interactions with the rock for the SICAL is presented.

Unraveling the role of Myotis myotis in the ecology and transmission of rabies-related lyssaviruses (RRLVs)

Purpose: Insectivorous bats have been found to carry a variety of Rabies-Related Lyssaviruses (RRLVs) across Europe, among which European bat Lyssavirus 1 (EBLV-1) is the most widely distributed. Despite the majority of lethal infections are reported from serotine bats, serological data suggest that other species might have a role in the ecology of this pathogen. EBLV-1 has been associated with spillover events to humans, domestic and wildlife animals, causing a neurological disease clinically indistinguishable from classical rabies. Unraveling its ecology would then be crucial in predicting and mitigating associated risks for public health. Methods & Materials: During 2012-2018, we investigated the role of Myotis myotis in the maintenance and transmission of EBLV-1, through the longitudinal screening of roosts for neutralizing antibodies and viral shedding. Five neighboring maternal colonies were investigated in Northern Italy, whose connectivity was assessed using genetic and capture-recapture studies. Results: Antibodies neutralizing EBLV-1 were detected yearly, confirming that M. myotis are constantly exposed to the virus in the area and do survive the infection. In addition, longitudinal data revealed wide oscillations of antibodies during a single reproductive season, suggesting waning of antibodies and waves of infection. All colonies showed similar serological trends over consecutive years. Indeed, we found evidence for genetic panmixia at the nuclear and mitochondrial level and confirmed the movement of adult females between roosts. Conclusion: Altogether, our results support the role of M. myotis as natural host for an EBLV1-like RRLV. While this bat species usually inhabits underground sites in the Mediterranean areas, M. myotis is a strictly house dweller species in northern areas, with all colonies investigated in this study being located in church roofs. Based on both serological and virological findings, we suggest that the risk for human exposure to the virus is limited, with viral excretion restricted to short predictable windows of time. We predict that this study will be useful to secure public health while maintaining a positive relationship between humans and these large vesper bats, whose critical role in the control of pest insects is well recognized in the area.

An integrated ARAS and interval type-2 hesitant fuzzy sets method for underground site selection: Seasonal hydrogen storage in salt caverns

The hydrogen seasonal storage, as pure gas or mixture with natural gas, is expected to sustain both the energy storage and sectorial integration. The salt caverns are able to store the large quantities of hydrogen at elevated pressures for seasonal period of time. In this study, a new approach integrating Additive Ratio ASsessment (ARAS) method and interval type-2 hesitant fuzzy sets (IT2HFSs) is proposed to tackle the underground hydrogen storage site selection problem in Romania. This study presents an integrated method to select the best location among four alternative sites based on 7 main and 14 sub-criteria. The result shows that the proposed method can be useful to handle fuzzy multi criteria decision-making (MCDM) problems.

I. ABTEILUNG - Excavations at St. Paul’s Catacombs: New Evidence at an Old Site

Excavations at St. Paul’s Catacombs: New Evidence at an Old Site Featuring more than 24 catacombs, the St. Paul’s Catacombs at Rabat have always been considered an important asset for Malta’s archaeological context. This paper gives a preliminary assessment of ongoing post-excavation work following extensive excavations carried out as part of Heritage Malta’s Archaeological Heritage Conservation Project between 2010 and 2015. These excavations revealed that the story of the site dates back to centuries before the first catacombs began to be dug. The initial human intervention at the area appears to have been as a quarry, possibly dating back to the Phoenician-Punic period. This quarry was subsequently used for the excavation of a number of shaft-and-chamber tombs and surface burials of cremated and infant inhumations. The Late Roman catacombs themselves were also part of the investigation; this article is an outline of the main discoveries within one of the excavated catacombs – catacomb 8. The underground burial site provided the largest amount of human bones and artefacts, which may give new insights into this period of the Maltese islands. This paper does not aim to give an exhaustive account or complete results, but instead outlines the highlights of these excavations and some of the preliminary interpretations.

Evaluating the Importance of Barometric Pumping for Subsurface Gas Transport Near an Underground Nuclear Test Site

Core Ideas Gas transport modeling can estimate ground surface breakthrough after an underground nuclear explosion. Comparison tracer‐injection experimental and model results reveals parameter sensitivity. Barometric pumping may explain gas breakthrough following an underground nuclear explosion. Amplitude and period of barometric pressure signal are key in controlling breakthrough. An underground nuclear explosion (UNE) generates and distributes radioactive gases that can be transported to the ground surface though preexisting and explosion‐induced fractures over timescales of hours to months. If detected, the presence of short‐lived radionuclides in gas is evidence of a recent UNE. Numerical modeling can provide estimates of surface arrival times that can help inform gas monitoring strategies at suspected foreign test sites. Efforts are underway at historic US UNE sites to better understand subsurface gas‐transport processes following a UNE by geologic characterization of the near‐field damage structures, field‐scale tracer experiments, and subsurface air pressure monitoring. The development of numerical models using historical and experimental datasets from former UNE sites can improve predictions by testing conceptual models, highlighting key processes, and constraining parameter ranges. The models developed in this study represent the U20az site at the Nevada National Security Site where the Barnwell device was expended in December 1989. A two‐phase (water and air), dual‐permeability flow and transport model of the U20az site was built to investigate gas transport processes under recent experimental conditions and following the Barnwell nuclear event. Results indicate that the model can explain both the lack of arrival of radioactive gas tracers in a 2013 field experiment as well as the observed arrival of radioactive gases following the 1989 Barnwell event using barometric pressure records from the respective periods, even when additional advective processes associated with the Barnwell detonation are ignored. The results demonstrate that the character of the barometric records may be a key factor in explaining the differences in transport behavior.

Airborne bacteria cultivated from underground hibernation sites in the Nietoperek bat reserve (Poland)

Airborne bacteria cultivated from underground hibernation sites in the Nietoperek bat reserve (Poland)

Guidelines for health and safety and fire safety on underground construction sites

AbstractUnderground construction sites represent a complex challenge for all project participants. Precisely in the area of health and safety as well as fire safety, therefore, good coordination is necessary in order to successfully counteract the increased accident and health risks. Clear definition of tasks and responsibilities is therefore essential. Through a continuous risk management process, it is possible to ensure from the design phase to the construction phase that risks can be minimized in advance and that the best risk reduction measures can be derived. The Guideline and Regulation for the Planning, Construction and Maintenance of Roadways (RVS) 09.01.51 ”Health and Safety on underground construction sites“ provides the necessary basis for this and thus represents an essential tool for all project participants to improve the level of safety.