Hydraulic conductivity field testing

The tracer test was carried out in a single realization of the heterogeneous hydraulic conductivity field. There are number of other realizations satisfying the same statistical properties, each potentially yielding different aL values. Since Equation 15.9 yields a theoretical value that represents the average over all possible realizations of the K field, one could expect the value of a single realization to be different. 

Uses raw data from field tests to compute hydraulic conductivity computed value is evaluated by the expert system for its correctness with regard to these considerations site-specific geological characteristics, validity of test procedures, accuracy of the raw data, and the computational method. System is written in Arity-Prolog on a PC. 

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. ... 

The airflow equations presented above are based on the assumption that the soil is a spatially homogeneous porous medium with constant intrinsic permeability. However, in most sites, the vadose zone is heterogeneous. For this reason, design calculations are rarely based on previous hydraulic conductivity measurements. One of the objectives of preliminary field testing is to collect data for the reliable estimation of permeability in the contaminated zone. The field tests include measurements of air flow rates at the extraction well, which are combined with the vacuum monitoring data at several distances to obtain a more accurate estimation of air permeability at the particular site. 

This section discusses soil liners and their use in hazardous waste landfills. The section focuses primarily on hydraulic conductivity testing, both in the laboratory and in the field. It also covers materials used to construct soil liners, mechanisms of contaminant transport through soil liners, and the effects of chemicals and waste leachates on compacted soil liners. 

The soil used in the experiment was a low plasticity sandy material with a PI of about 11%. The variations in hydraulic conductivity probably reflected zones of material that contained more sand in some places and more clay in others. Tests have been performed on a couple of liners in the field where liquid flowing into the soil liners has been dyed and traced by cutting a cross section or trench through the liner. The result seems to indicate that dyed liquid finds a defect in the top lift, moves down and spreads along a more permeable zone between lifts finds another defect, moves downward, spreads finds another defect and so forth. 

The tests were replicated under controlled conditions using soil collected from the liner in thin-walled 3-in. diameter sample tubes. The laboratory measures of hydraulic conductivity were consistently 1 x 10 9 cm/s, five orders of magnitude lower than the field value of 1 x 10-4 cm/s. The laboratory tests yielded a hydraulic conductivity 100,000 times different from that from the field test. Apparently, the flow through the 3-in. specimens did not mimic the flow on a larger scale... 

One implication of these experiments for laboratory hydraulic conductivity testing is that conductivity values can vary remarkably depending on the confining stress. It is essential that the confining stress used in a laboratory test be of the same magnitude as the stress in the field. 

In situ, or field, hydraulic conductivity testing operates on the assumption that by testing larger masses of soil in the field one can obtain more realistic results. There are actually four kinds of in situ hydraulic conductivity tests5 ... 

There is a radical variation in the reliability of field tests versus laboratory tests. In the Houston test pad discussed earlier, the real value for hydraulic conductivity in the field was 1 x 10 4 cm/s, while the lab value was 1 x 10 9 cm/s, a 100,000-fold difference in the values. 

State codes require the following tests to demonstrate the constructed quality of landfill clay liners and final cover clay layers dry density and moisture content, grain size analysis up to 0.002 millimetre particle size, Atterberg limits, and hydraulic conductivity of field samples. 

The vertical hydraulic conductivity of saturated loess (Kg) in this study, we used the parameter obtained by the field artificial rainfall simulation test in the south-central channel of Shaanxi... 

JAEA conducted an improvement of the RELAP5 MOD3 code (US NRC, 1995), the system analysis code originally developed for LWR systems, to extend its applicability to VHTR systems (Takamatsu, 2004). Also, a chemistry model for the IS process was incorporated into the code to evaluate the dynamic characteristics of process heat exchangers in the IS process (Sato, 2007). The code covers reactor power behaviour, thermal-hydraulics of helium gases, thermal-hydraulics of the two-phase steam-water mixture, chemical reactions in the process heat exchangers and control system characteristics. Field equations consist of mass continuity, momentum conservation and energy conservation with a two-fluid model and reactor power is calculated by point reactor kinetics equations. The code was validated by the experimental data obtained by the HTTR operations and mock-up test facility (Takamatsu, 2004 Ohashi, 2006). 

Vicksburg MS, remaining there all through his career until retirement in 1985. He eventually became chief of the Hydrodynamics Branch, responsible for the conduct of all hydraulic model tests of hydraulic structures, dams, and harbour developments. He has had a large impact on the hydraulic laboratoiy test procedures in the USA, counting among the experts in this field. Brown was a member of the American Society of Civil Engineers ASCE and elected to its Honorary Member in 1981. 

The configurations are shown in Figure 2. Initially, hydraulic testing was conducted at QU and then the pilots were relocated to the QEWC power/desalination plant at Ras Abu Fontas to operate under field conditions. 

The alternative pillow test was originated by Tom Stephens of Ten Cate in about 2005 (Ten Cate Geosynthetics, Inc., 2007) and formalized as a standard in 2009 (GRTGT15). The only related references in the open literature are the work of Professor Bhatia and her students at Syracuse University, who developed and conducted research on a similar test which they called the pressure filtration test (Bhatia and Liao, 2004 Satyamurthy et al., 2008, 2009). Hydraulic pressures were measured and quantitative data were produced but the laboratory configuration was different from the field-simulated pillow test, which is described subsequently. 

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