Fine-grained soils

Silt and clay are fine-grained soils in which individual particle size cannot be readily distinguished with the unaided eye. Some classification systems distinguish these particles by size, other systems use plasticity to classify these particles. 

Atterberg-limit tests determine the water content influence in defining liquid, plastic, semisolid and solid states of fine-grained soils. Permeability tests may be carried out in the laboratory or in the field. Such tests are used to determine the hydraulic conductivity coefficient k. ... 

Electroosmotic soil processing is an in situ separation/removal technique for extracting heavy metals and organic contaminants from soils.17 55 89 The fluid between the soil particles moves because a constant, low DC current is applied through electrodes inserted into the soil mass. The electroosmosis (EO) remedial method provides an advantage over conventional pumping techniques for in situ treatment of contaminated fine-grained soils and is more efficient in saturated conditions. 

Fine-grained soils, such as silts and clayey silts, that have a relatively high water storage capacity. 

FIGURE 26.6 ASTM plasticity determination for fine-grained soils. (Adapted from U.S. EPA, Requirements for Hazardous Waste Landfill Design, Construction, and Closure, EPA/625/4-89/022, U.S. Environmental Protection Agency, Cincinnati, OH, August 1989.)... 

Jet u 200 M drilling fluids required smearing of borehole walls in fine-grained soils and sediments causing sealing Diameter limitations fluid level (water and NAPL) difficult sampling accuracy limited produced fluids... 

Fine-grained soils and low volatile hydrocarbons limit elfectiveness... 

Fine-grained soils and permeability constrasts limit ability to inject steam and recover fluids from subsurface... 

Fine-grained soils or permeability contrasts limit effectiveness Requires ongoing operation and maintenance... 

Cleanup strategies for hydrocarbon-affected soil will most likely be the last issue to be mandated from a regulatory perspective and certainly the most difficult technically to address. This difficulty reflects the large, deep-seated volumes of residual hydrocarbon present, and the current lack of efficient, cost-effective methodologies for in situ remediation of residual hydrocarbons in low-permeability, fine-grained soils. 

This technology cannot be located near noise-sensitive areas. The operating system does not work well in temperature extremes, such as below 30 or above 100°F. The technology is ex situ, requiring soil excavation. The technology changes the physical characteristics of fine-grained soils such as clay and topsoil. 

The costs associated with the PAT process will vary based on site-specific conditions and the costs of pozzolan additives, operating safety requirements, and labor. The estimated costs associated with the stabilization of fine-grained soils that do not require pretreatment and do not pose extreme handling hazards are between 30 and 50 per ton. For the stabilization of coarsegrained soils, costs were estimated between 40 and 60 per ton. Pretreatment, containment, and high-efficiency particulate air (HEPA) filtration would add to these cost estimates (D20799S, pp. 23, 24, 66). 

Applicability in fine-grained soils around buried structures (tanks, pipes, etc.) may be limited because of soil movement. 

Soil type and heterogeneity of the soil influence well locations and well screen intervals. As the percentage of fine grains in the soil increases, permeability decreases and water content increases. In fine-grained soils, the effective radius of treatment of DVE is reduced, meaning there is a smaller area where the vacuum is sufficient to induce in situ volatilization of hydrocarbons. 

At the end of this section focused on analytical problems, it should be mentioned that Thoming et al. [199] have evidenced that electrodialysis allows one to remove heavy metals from soils. During this process, the metals, including mercury, are transferred under the applied electric field to the pore water in either dissolved form or attached to colloids. This method is especially appropriate for the purification of fine-grained soils. 

Growth Medium and Frost Protection (Fine-Grained Soil)... 

Kim, Kim and Kim (2005) evaluated the treatment of arsenic in two fine-grained soils with an ex situ electrokinetic technology, which consisted placing the samples in a three-compartment chamber with a platinum anode and titanium cathode on opposite ends. One soil consisting of a Korean kaolinite was spiked with 1500 mg kg-1 of As(V). The second soil sample, which contained 3210 mg kg-1 of arsenic, was collected from the abandoned Myungbong gold mine in southern South Korea. The soils were treated with NaOH or KH2P04 electrolyte solutions. Deionized water was used with control samples to establish a baseline. 

Various new devices that have been used in soil sampling include a gravity-driven, hydraulically sampled multi-piston corer for fine-grained soils [11] and time-series trap that can collect 21 samples of soil at programmed intervals [12]. 

Fine grained soil comprising complex mixtures of mineral and glass fragments and microbreccias4 7 ... 

There are a number of specializes stabilizers for which there is little technical information or test data. These stabilizers are sold imder trade names. These products are only useful in stabilizing fine-grained soils [4]. 

Figure 20 Soil carbonate morphology and amount versus time for (a) gravelly and (b) fine-grained soils etal, 1966) (reprodueed by permission of Williams and Wilkins from 5 //5c/. 1966,101, 347-360).

Applying stress to any material results in a corresponding strain. For the common building materials such as steel and concrete the strain occurs virtually instantaneously with stress application. In contrast, fine-grained soils generally exhibit a measurable time lag between stress application and the resulting strain. This phenomenon is called consolidation. 

When a load is applied to a saturated fine-grained soil, it is instantaneously carried by the water as excess pore pressure. The water immediately begins to flow away from the point of maximum stress, and as it does so the load is transferred to the soil matrix, which deforms under the load. The finer the pores in the soil, the longer it takes for the pore water pressure to approach zero, and for settlement under the load to become negligible. In the field, the process could take months or years. 

Silt—Silt consists of mineral grains ranging from about 0.05 to 0.002 mm in size. It is a fine-grained soil lacking plasticity and having little or no dry strength. 

Static Fine-grained soils with more Dams, embankments. Clean coarse-grained soils. 

Semipervlous fine-grained soils—Zone 2 and clay fills above the water table— Zone 3 of Figure 5 250-350 41-60... 

Soft, fine grained soils 40 soils with large voids or cavities... 

Pathfinder), 4000 km apart in the northern hemisphere gave similar basaltic compositions for the fine-grained soils that were analyzed the fine material will contain a significant component from the ancient cratered terrain that dominates the southern hemisphere, where most of the global dust storms originate. However, no component more siliceous than basalt appears in the Martian compositions. At the Pathfinder site, more siliceous rock... 

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