Moisture characteristic, soil

The HAVE System is a simple, effective, and low-cost technology that completely destroys the contaminants that it removes. However, variables such as pile temperature, soil characteristics, soil moisture, and porosity can negatively affect the performance of HAVE. 

The bathtub effect occurs, in part, because most wastes have much higher hydraulic conductivities than the natural material into which they are placed they may also have very different unsaturated soil—moisture characteristics. The hydraulic conductivity of some wastes can be reduced by compaction. The bathtub effect also occurs because more infiltration enters the disposal excavation than would under normal undisturbed conditions. Trench covers may be constructed to achieve the desired hydraulic conductivity and to limit infiltration for the required period of containment or until compaction of the wastes occurs however, it is difficult to maintain the trench covers. The covers must withstand attack by plants, weather (freeze—thaw, wet—dry), erosion, and strains caused by consolidation within the trench. Most trench covers are not capable of meeting these demanding requirements without costly long-term maintenance programs. The cover should be designed to allow for expected consolidation and to utilize hydro-geological concepts of saturated and unsaturated flow systems present at the site. 

Soil Moisture Characteristic. The relationship between water content and the matric component is referred to as the "soil moisture characteristic." Although this relationship comnonly displays hysterysis, the effect is not significant for most applications. 

Childs, E.C. 1940. The use of soil moisture characteristics in soil studies. Soil Sci. 50 239-252. 

Standard procedures for soil testing, such as density characteristics, soil texture, and moisture content. 

The moisture characteristic (moisture content versus soil suction) of a soil provides valuable data concerning the moisture contents corresponding to the field capacity (defined in terms of soil suction, this Is a pF value of about 2.0) and the permanent wilting point (pF of 4.2 and above), as well as the rate at which changes In soil suction take place with variations in moisture content. This enables an assessment to be made of the range of soil suction and moisture content that is likely to occur In the zone affected by seasonal changes In climate. 

A.S. Rogowski, Watershed Physios Model of The Soil Moisture Characteristic, Water Resour. Res., Vol.7, pp.1575-1582, 1971. 

In the presence of NAPL, the concentration of contaminants in the soil moisture (Cw) can be calculated simply from the solubility of the compounds (equation 3 in Table 14.3). Adsorption of contaminants to the soil particles is a much more complex phenomenon, which depends both on contaminant properties and on soil characteristics. The simplest model for describing adsorption is based on the observation that organic compounds are preferentially bound to the organic matter of soil, and the following linear equation is proposed for calculating the adsorbed concentration (Cs) ... 

Soils and vadose zone information, including soil characteristics (type, holding capacity, temperature, biological activity, and engineering properties), soil chemical characteristics (solubility, ion specification, adsorption, leachability, cation exchange capacity, mineral partition coefficient, and chemical and sorptive properties), and vadose zone characteristics (permeability, variability, porosity, moisture content, chemical characteristics, and extent of contamination)... 

Physico-chemical characteristics of the soils were summarized in Table 1. The values were comparable to that described in the previous reports about the SERS (Doi and Sakurai 2003 Doi et al. 2004 Sakurai et al. 1998). The one-way ANOVA indicated that most of the soil variables significantly reflected the land degradation with high values of bulk density, sand content and exchangeable acidity, and low values of moisture content, pH, OM, base (K, Ca, Mg) contents, EC, CEC, base saturation rate, TN and TC contents, available phosphorus and MPN on the glucose medium with no antibiotics. These results also told that the human activities induced several soil environmental gradients. 

Denitrification, a dissimilatory pathway of nitrate reduction (see Section 3.3 also) into nitrogen oxides, N2O, and dinitrogen, N2, is performed by a wide variety of microorganisms in the forest ecosystems. Measurable rates of N20 production have been observed in many forest soils. The values from 2.1 to 4.0 kg/ha/yr are typical for forest soils in various places of Boreal and Sub-Boreal Forest ecosystems. All in situ studies (field monitoring) of denitrification in forest soils have shown large spatial and temporal variability in response to varying soils characteristics such as acidity, temperature, moisture, oxygen, ambient nitrate and available carbon. 

Sites suitable for conventional SVE have certain typical characteristics. The contaminating chemicals are volatile or semivolatile (vapor pressure of 0.5 mm Hg or greater). Removal of metals, most pesticides, and PCBs by vacuum is not possible because their vapor pressures are too low. The chemicals must be slightly soluble in water, or the soil moisture content must be relatively low. Soluble chemicals such as acetone or alcohols are not readily strippable because their vapor pressure in moist soils is too low. Chemicals to be removed must be sorbed on the soils above the water table or floating on it (LNAPL). Volatile dense nonaqueous liquids (DNAPLs) trapped between the soil grains can also be readily removed. The soil must also have sufficiendy high effective porosity (permeability) to allow free flow of air through the impacted zone. 

Effect of pathogens on tree carbohydrate concentration and relationship of carbohydrate concentrations to pathogen attack 24b Effect of path< ns on water uptake and transpiration 24c Relation ip between stem and root characteristics and pathogen attack 2Sa Effect of soil moisture and temperature on water uptake and transpiration 2Sb Effect of soil mineral concentration and temperature on mineral nutrition of... 

M. (1992) Moisture effects on visible spectral characteristics of lateritic soils. Soil Sci. 153 129-141... 

Characteristics of soil Quantity of waste Utility/fuel rates Moisture content of soil Initial contaminant concentration Characteristics of residual waste Waste handling/preprocessing Target contaminant concentration Amount of debris with waste Labor rates... 

Among the factors that affect the cost per unit price are initial contaminant concentration, target contaminant concentration, moisture content of the soil, and soil characteristics (D10018L, p. 13). 

The process has limited application for soils contaminated with polychlorinated biphenyls or any other dioxin precursor. Semivolatile compounds with boiling points greater than 800°F cannot be effectively removed from the soil in a one-pass treatment. The soil characteristic that most affects treatment is moisture content. All information in this summary is based on information provided by the vendor and has not been independently verified. 

Cost estimate for the Carlo Environmental Technologies, Inc., MTTD technology range from 30 to 69 per ton of soil or other material treated. Factors that influence costs are characteristics of the soil (most important) utility and fuel rates, and moisture content of the soil. The initial and target contaminant concentrations also affect costs (D101871, p. 28). 

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