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Hydrogeology
Published in Mohammad Albaji, Introduction to Water Engineering, Hydrology, and Irrigation, 2022
An aquifer is an underground layer consisting of water-bearing permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Aquifers produce a feasible quantity of water to be used through a spring or a well. The flow of groundwater from one aquifer to another restricts by aquitards. Aquitards consists of clay or non-porous layers of rock with low hydraulic conductivity. Aquifers are classified in different ways based on their characteristics (Figure 5.1).
The Dual Porosity Model
Published in Abdon Atangana, Mathematical Analysis of Groundwater Flow Models, 2022
Siphokazi Simnikiwe Manundu, Abdon Atangana
For both categories, aquifers can be further grouped into three other types, namely unconfined, confined, and leaky aquifers (Skinner et al., 2004). The unconfined aquifer may be defined as a geological layer with no confining layer above the aquifer, whereas with the confined aquifer, the geological layer is bounded by confining beds above and beneath it, resulting in the groundwater being subjected to pressure greater than that of the atmosphere. Lastly, the leaky aquifer geological layer is bounded between aquitards that allow for minimal water to travel through.
Common Properties of Chemicals of Concern and Soil Matrices
Published in Cristiane Q. Surbeck, Jeff Kuo, Site Assessment and Remediation for Environmental Engineers, 2021
Cristiane Q. Surbeck, Jeff Kuo
A leaking UST is illustrated in Figure 2.5. The vadose zone (also called the unsaturated zone, or zone of aeration) is the subsurface between the ground surface level (gsl) and the water table. The soil in the vadose zone is not fully saturated with water; in other words, the pores contain both air and water. Below the water table is the phreatic zone, in which the soil is saturated with water (i.e., the aquifer). The water table is the interface between the vadose zone and the uppermost aquifer.
Pathogen contamination of groundwater systems and health risks
Published in Critical Reviews in Environmental Science and Technology, 2023
Yiran Dong, Zhou Jiang, Yidan Hu, Yongguang Jiang, Lei Tong, Ying Yu, Jianmei Cheng, Yu He, Jianbo Shi, Yanxin Wang
With the increasing demand for groundwater due to the growing population, socio-economic development, and industrialization, greater attention has been focused on its quality and safety. Among the 17 Sustainable Development Goals of the United Nations, at least 13 of them are directly or indirectly associated with groundwater (United Nations, 2022). As groundwater is not as susceptible to contaminants as surface water, it has been widely used as a source of drinking water. Some engineering strategies such as bank filtration and artificial recharge groundwater have been employed for aquifer management. Increasing evidence, however, showed under-managed groundwater can be vulnerable to the risks by pathogenic contaminants. So far, a large number of waterborne disease outbreaks have been attributed to pathogen contamination in groundwater and GDEs (Krauss and Griebler, 2011; WHO, 2017b). The recent pandemics and our growing understanding of an unprecedented number of novel pathogens have raised widespread concerns about the biological integrity of vulnerable groundwater and how we can prepare for the next public health crisis (Carroll et al., 2018; EU, 2021). At the same time, rapid progress in technologies has facilitated more sensitive, accurate, efficient, and affordable approaches to detect and monitor waterborne pathogens (Váradi et al., 2017). Confronting these challenges and opportunities, it is critical to reassess groundwater bio-integrity from an ecological perspective, identify knowledge gaps, describe possible synergies and tradeoffs, and give an outlook for the future of groundwater biosafety.
Soil and groundwater remediation proposal for hydrocarbons in a tropical aquifer
Published in Journal of Applied Water Engineering and Research, 2023
Adriana Márquez, Estafania Freytez, Julio Maldonado, Edilberto Guevara, Sergio Pérez, Eduardo Buroz
The lithological profiles of fifteen MWs (Figure 1(b)) are shown in Figure 5. All the fifteen soil profiles contain alternate strata composed of sand and clay (impervious formation) for a depth varying between 8 and 20 meters below the ground surface (mbgs), being classified as a confined aquifer. A confined aquifer is one that (1) is bounded from above and below by impervious formations, and (2) the water pressure in it is such that the level of water in a well that is open in it will be at, or will rise above the upper impervious bounding surface (Bear and Cheng 2010). The clayey strata have a thickness that ranges from 4 to 10 m in the vadose zone and the interface between the vadose (unsaturated) and saturated zones (Figure 5). The presence of clayey strata in a significant thickness within the vadose zone is the main cause by which in-situ bioremediation is difficult to be implemented, since soils that are very stratified and clayey do not favor air distribution in the polluted zone (Álvarez and Guevara 2003; Guevara 2016). The soil profiles located within the gas station area gave similar alternate sequences of sand and clay (MW-1, MW-5, MW-6. MW-8, MW-9, MW-10, MW-11, M-12 and MW-14), and existing connectivity in the strata between this sample of soil profiles.
Soil and groundwater remediation proposal for hydrocarbons in a tropical aquifer
Published in Journal of Applied Water Engineering and Research, 2022
Adriana Márquez, Estafania Freytez, Julio Maldonado, Edilberto Guevara, Sergio Pérez, Eduardo Buroz
The lithological profiles of 15 MWs (Figure 1(b)) are shown in Figure 5. The 15 soil profiles contain alternate strata composed by sand and clay (impervious formation) for a depth varying until 8 and 20 m below ground surface (mbgs), being classified as a confined aquifer. A confined aquifer is one that (1) is bounded from above and from below by impervious formations, and (2) the water pressure in it is such that the level of water in a well that is open in it will be at, or will rise above the upper impervious bounding surface (Bear and Cheng 2010). The clayey strata have a thickness that ranges from 4 to 10 m in the vadose zone and in the interface between the vadose (unsaturated) and saturated zones (Figure 5). This is the main cause by which the in situ bioremediation is difficult to be implemented, since the soils very stratified and clayey do not favor the air distribution in the polluted zone (Álvarez and Guevara 2003; Guevara 2016). The soil profiles located within the gas station area gave similar alternate sequences of sand and clay (MW-1, MW-5, MW-6, MW-8, MW-9, MW-10, MW-11, M-12, and MW-14), existing connectivity in the strata between this sample of soil profiles.