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Permanent Groundwater Control Systems
Published in Pat M. Cashman, Martin Preene, Groundwater Lowering in Construction, 2020
For most temporary construction dewatering systems, the capital cost of equipment and the cost of installation will be much greater than the operating costs (e.g. power costs, spare parts and other consumables). On most temporary dewatering projects, little effort is made to maximize efficiency of operation, the focus often being on speed of installation and use of standardized equipment.
Geotechnical Considerations
Published in Paul W. McMullin, Jonathan S. Price, Sarah Simchuk, Special Structural Topics, 2018
High water tables, or high water pressures in lower strata, will affect foundation construction and need to be designed around or mitigated. Groundwater control methods include interception and removal (via sumps, wells, or drains), reduction of pressure, and isolation of the excavation (via cutoff walls, grout curtains, or freezing). Again, we must consider the effect on neighboring structures: lowering a water table will result in increased pressure on existing surrounding foundations. The dewatering method will depend largely on site conditions, but will also take into consideration designer and contractor capability. It is not unusual to require the contractor to provide a dewatering design for designer approval. An extensive discussion of dewatering methods and practice is available in the Army Technical Manual 5–818–5, Dewatering and Groundwater Control.11
Foundation Stabilization and Construction Dewatering
Published in Ian Watson, Alister D. Burnett, Hydrology, 2017
Ian Watson, Alister D. Burnett
In the content discussed, dewatering is primarily a construction tool used to lower the water table on a temporary basis so that deep foundations may be built in the dry (Figure 12-10). Linear well-point dewatering systems of the type shown in the Chapter 12 Frontispiece and in Figure 12-11 are also used on a temporary basis for installing pipelines and sewers in the dry. Permanent dewatering systems are sometimes installed as a design “fix” to protect foundations, prevent the flooding of basements and so on. Mining dewatering systems, although in a strict sense temporary, must be designed for fairly long-term use.
Demulsifying of waste oils in a port reception facility by ultrasound with a new coagulant: techno-economic evaluation
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Nurullah Özdoğan, Ahmed M. Albahnasawi, Havva Ağır, Serkan Arslan, Okan Gunaydin, Ercan Gürbulak, Murat Eyvaz, Ebubekir Yüksel
To the best of our knowledge, there is no detailed technical and economic analysis study on the dewatering of emulsions (oil-in-water), such as ship waste oils. In this study, demulsifying real ship waste oils coming to a port reception facility with a pilot-scale ultrasound probe was aimed. Existing dewatering applications in the facility were compared with the application of ultrasound. Also, a chemical developed as an alternative to commercial demulsifiers was used as an emulsion breaker. First, the performance of the existing dewatering methods in the facility was analyzed both individually and in combination. The studies were carried out in three main steps. While the effect of only heating on dewatering was tested in the first step, chemicals were also used in addition to heating in the second step. Finally, chemicals and ultrasound were applied together without heating. In the experiments employing chemicals, available commercial and a newly synthesized demulsifier in the plant were also compared. The water content of the dewatered waste oil was used as the main performance parameter, and a detailed economic evaluation was carried out considering all operational parameters (chemicals, labor, and electricity) in the facility. The results of this study are expected to guide (i) the technical and economical waste oil management/dewatering in similar port reception facilities, (ii) the reduction of the organic load of the sequent treatment plant, and (iii) the installment of industrial-scale dewatering processes that can be utilized in similar facilities.
Determining the portion of dewatering-induced settlement in excavation pit projects
Published in International Journal of Geotechnical Engineering, 2021
Mahdi Khosravi, Mohammad Hossein Khosravi, Seyed Hossein Ghoreishi Najafabadi
Dewatering operation for excavation pits may result in surrounding ground settlement and serious damage to adjacent buildings. In general, the ground settlement is the result of two main factors, dewatering and excavation. Knowing the portions of settlements due to each of these factors can help to control the settlement. The Taklar 2 excavation pit project located at north-eastern part of Tehran city was used as a case study for this research. In order to determine the dewatering-induced settlement, the settlement due to excavation and dewatering were determined separately by using numerical and analytical methods. The numerical and analytical data were compared with some monitoring data measured directly at the field and it was concluded that:
Investigating impacts of deep foundation pit dewatering on land subsidence based on CFD-DEM method
Published in European Journal of Environmental and Civil Engineering, 2022
Xuan Zhang, Lihua Wang, Hualao Wang, Chunlei Feng, Haojie Shi, Shengzhi Wu
The cut and cover method is widely used in urban shallow tunnelling projects (Han et al., 2017; 2018). For deep excavations, dewatering is a process to prevent groundwater from penetrating into the pit and ensure the foundation pit can be constructed under dry conditions. When the project is located in water-rich strata, the dewatering process must be carried out, which, however, is very likely to cause washaway of fine particles in the sandy cobble stratum (Figure 1) and result in considerable land subsidence. Therefore, it is of great significance to design the dewatering process reasonably to keep land subsidence in check (Galloway et al., 1999; Teatini et al., 2012; Zhang et al., 2015).