Simulation of contaminant migration through a soil layer due to an instantaneous source

2011 ◽  
Vol 19 (2) ◽  
pp. 385-398 ◽  
Author(s):  
Erdal Cokca ◽  
H. Tolga Bilge ◽  
Berna Unutmaz
Keyword(s):  
Soil Layer ◽  
Contaminant Migration ◽  
Instantaneous Source

Effect of multiple contaminant migration on diffusion and adsorption of some domestic waste contaminants in a natural clayey soil

1989 ◽  
Vol 26 (2) ◽  
pp. 189-198 ◽  
Author(s):  
F. S. Barone ◽  
E. K. Yanful ◽  
R. M. Quigley ◽  
R. K. Rowe
Keyword(s):  
Diffusion Coefficient ◽  
Clayey Soil ◽  
Chemical Constituents ◽  
Soil Layer ◽  
Laboratory Model ◽  
Contaminant Migration ◽  
Adsorption Parameters ◽  
Domestic Waste ◽  
Diffusion Parameters ◽  
Initial Source

This paper describes laboratory model tests involving the placement of domestic landfill leachate on top of a layer of saturated undisturbed clayey soil and allowing chemical constituents to migrate into the soil by diffusion only. During the testing period (15 days), samples from the overlying leachate were regularly collected and analyzed for the chemical constituents of interest (i.e., Cl−, Na+, K+, Mg++, and Ca++). At the end of the test, the soil layer was sectioned to determine the pore-water and adsorbed concentration variations with depth for each species. Mathematical model POLLUTE was then used to back-figure both the diffusion coefficient (D) and the adsorption term (ρK). The measured diffusion coefficients at a temperature of 10 °C were determined to be [Formula: see text], [Formula: see text], and [Formula: see text]. The corresponding adsorption terms were [Formula: see text], [Formula: see text], and [Formula: see text].Ca++ and Mg++, originally predominant on the clay exchange sites, were heavily desorbed to accommodate the adsorption of migrating Na+, K+, and possibly NH4+, causing hardness halo effects that the model could not fit. This behaviour corresponds to that commonly observed at domestic waste sites in southern Ontario.The importance of multiple contaminant migration on diffusion rates was assessed by comparing the leachate models with similar models using a variety of single salts dissolved in distilled water as the source solutions. For the single-salt models, all species considered, including Ca++ and Mg++, behaved in a way that could be described by conventional Fickian theory. A comparison of the diffusion and adsorption parameters obtained from the two types of models indicated that for both Na+ and K+, the measured D and ρK from the leachate models were 20 and 60% lower, respectively, than the values obtained from the single-salt models. For Cl−, the diffusion coefficient obtained from the leachate models was 25% higher than that obtained from the single-salt models.For the Sarnia grey soil used, both D and ρK are significantly influenced by the types and amounts of co-diffusing species present in the initial source solutions. Laboratory tests conducted to determine diffusion parameters for use in design should be run with soils and source solutions chemically identical to those expected in the field. Key words: domestic waste leachate, multiple contaminant migration, clayey soil, diffusion, adsorption, laboratory study.

Impact Assessment of Dynamic Characteristics on the Hydraulic Driven Machinery Operation

2018 ◽  
pp. 1-12
Author(s):  
A. D. Terenteva
Keyword(s):  
Dynamic Error ◽  
Total Error ◽  
Soil Layer ◽  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Working Mechanism ◽  
Automated Control ◽  
Vertical Coordinate ◽  
Construction Machinery ◽  
The Difference

In civil engineering in Russia, trenching for utilities is currently under digging. To perform such works, it is necessary to use high-precision construction machinery, because inaccurate performance of works can lead to the break down of existing utilities, thereby affecting the residents of nearby houses and demanding the additional works for renewal.The most universal labour saver to perform construction works is hydraulic driven single-bucket excavators, which provide up to 38% of works. Therefore, to improve technical characteristics that affect the accuracy of the work performed is an important task.High requirements for the performance of works are defined by existing construction regulations: an allowable soil layer to remain is at most 0.05 m. To fulfil such requirements, an exact assessment of the working mechanism position and a trench profile is necessary.Examination of a manually operated digging process shows that an operator provides operations untimely, however an automated control system can solve this problem. Dynamic phenomena in the working mechanism have the greatest impact on the accuracy of the works performed.To assess the bucket digging edge position accuracy, a mathematical model of the working mechanism has been created. Based on the cycle scheme of the working process, the excessive displacements of the hydraulic cylinder rods under the load are taken into account. By the end of the cycle, the difference between the specified and obtained positions along the vertical coordinate has been 0.0892 m.A dynamic error of the hydraulic drive system of the working mechanism is considered as a sum of the error due to excessive displacements of the hydraulic cylinder rods and the error due to delay of the hydraulic drive, with the latter being calculated for the average time of delay taking into account the data available in the literature. The total error of the bucket digging edge position of the working mechanism is 0.1176 m, which is 2 times more than the value of 0.05 mConformity of all the links with specification requirements does not guarantee compliance with the required displacement accuracy of the bucket digging edge, and, thus, the soil layer to remain in the base of the trench can exceed the regulated value of 0.05 m.

Prospects of spring wheat cultivation in the conditions of arid Volga region

2020 ◽  
pp. 28-33
Author(s):  
Valery Genadievich Popov ◽  
Andrey Vladimirovich Panfilov ◽  
Yuriy Vyacheslavovich Bondarenko ◽  
Konstantin Mikhailovich Doronin ◽  
Evgeny Nikolaevih Martynov ◽  
...  
Keyword(s):  
Spring Wheat ◽  
Soil Layer ◽  
Weather Conditions ◽  
Volga Region ◽  
Mineral Fertilizers ◽  
Climate Conditions ◽  
Wheat Cultivation ◽  
Forest Belts ◽  
Clear Differentiation ◽  
The Impact

The article analyzes the experience of the impact of the system of forest belts and mineral fertilizers on the yield of spring wheat, including on irrigated lands. Vegetation irrigation is designed to maintain the humidity of the active soil layer from germination to maturation at the lower level of the optimum-70-75%, and in the phases of tubulation-earing - flowering - 75-80% NV. However, due to the large differences in zones and microzones of soil and climate conditions and due to the weather conditions of individual years, wheat irrigation regimes require a clear differentiation. In the Volga region in the dry autumn rainfalls give the norm of 800-1000 m3/ha, and in saline soils – 1000-1300 and 3-4 vegetation irrigation at tillering, phases of booting, earing and grain formation the norm 600-650 m3/ha. the impact of the system of forest belts, mineral fertilizers on the yield of spring wheat is closely tied to the formation of microclimate at different distances from forest edges.

Cryogels as a solution to the issues of environmental management and trunk pipeline operation in Arctic

2020 ◽  
Vol 10 (2) ◽  
pp. 173-185
Author(s):  
Lyubov K. Altunina ◽  
◽  
Vladimir P. Burkov ◽  
Petr V. Burkov ◽  
Vitaly Y. Dudnikov ◽  
...  
Keyword(s):  
Composite Materials ◽  
Field Experiments ◽  
Oil And Gas ◽  
Soil Layer ◽  
Soil Microflora ◽  
Russian Arctic ◽  
Thaw Cycle ◽  
Trunk Pipeline ◽  
Geological Conditions ◽  
Spatial Lattice

In the Russian Arctic, a soil cryostructuring technique (i.e. strengthening of soil horizons with cryogel-based composite materials with no excavation of unstable soils required) seems to be showing promise. Experiments have proven that mechanical and thermal insulation properties attributed to cryogels make them appropriate for use in strengthening and thermally insulating the soil, while their structure makes it possible to form a stable vegetation cover. Field experiments have confirmed that cryostructuring efficiently strengthens the soil layer with cryogels stimulating soil microflora. An experience of using cryotropic compositions in the oil and gas sector was described. Notably, cryogels can be used to strengthen unstable soil foundations of trunk pipelines, as well as to bind soil (e.g. on slopes). In addition, cryogels are advised for use in engineering protection to prevent the uneven settlement of a trench base and its creep: thus, cryogels are pumped into the soil of the trench bottom base to create a support system representing a spatial lattice. After the first freeze and thaw cycle, cryotropic material is formed and then increases its strength and elasticity with each new cycle. More broadly, opportunities have been considered regarding cryogels used in various engineering and geological conditions, while taking into account the outcomes of landscape and territorial analysis. It was concluded that cryogel-based composite materials are a promising innovative scientific field expanding technological capabilities for developing and using spaces and resources in the Russian Arctic.

Sign in / Sign up

Export Citation Format

Share Document