Field scale experiments

This section provides some additional information about a few of the field scale experiments introduced in Section 8.5.1 under Modeling Methodologies Full Scale Fire Tests. 

Probably the most extensive and ambitious mass fire experiments were performed during the Flambeau project between 1964 to 1975. Approximately 25 separate large 

During 1970 Operation Euroka was performed in Queensland, Australia [645], This fire was principally of brigelow, a heavy dense hardwood. The slash was arranged by bulldozers into fire beds that had very little fine material hence the peak combustion rates were considerably later and lower than those of the U.S. A. fires. The fire had peak energy release rates of about 120 kW/m2. During Operation Euroka maximum winds were 20 m/s, and after 30 minutes a fire whirl developed. Winds tended to spiral inward from around the fire which covered an area of about 2 ha. 

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What will happen under field conditions is, however, highly uncertain. Laboratory experiments have been conducted under conditions of abundant nutrients and water, ideal temperatures, and no competition among experimental plants. Such conditions are rare in the field. The best prediction is that, whereas increases similar to those found in the laboratory are unlikely under field conditions, increased concentrations of CO2 are likely to ameliorate to some extent the detrimental effects of climate change. However, field-scale experiments under a variety of soils and climates and with several crop plants are needed to provide information on effects of climate change accompanied by higher concentrations of CO2 on agricultural productivity. 

High water flow rates or excessive turbulence are factors that can limit the success of microbial mats. In a field-scale experiment, a 50-cm snowfall flow dramatically increased water flow rates in the mat pond, causing severe damage to the mat. As a result, the pond had to be drained and reinoculated. Snails and other invertebrate herbivores have also been known to damage the mats. 

Kimball B. A., Runkel R. L., and Walton-Day K. (2003) Use of field-scale experiments and reactive transport modelling to evaluate remediation alternatives in streams affected by acid mine drainage. In Environmental Aspects of Mine Wastes, Mineral. Assoc. Canada Short Course Series 31 (eds. J. L. Jambor, D. W. Blowes, and A. I. M. Ritchie). Mineralogical Association of Canada, Ottawa, pp. 261-282. 

A complex system containing a branched anionic surfactant, non-ionic surfactants, rapeseed oil methyl ester and an aqueous calcium chloride solution was found to form bicontinuous microemulsions even at low temperatures [46, 90]. This type of microemulsion has been studied for DNAPL extraction on a large scale in an artificial aquifer and later in a joint project with different partners financed by the German Federal Ministry of Education and Research (BMBF) [91 ]. The project network applied an integrated concept regarding aspects of hydraulics, reuse and biodegradation [92]. Three large-scale experiments each with some hundreds of litres of preformed microemulsion were performed. Whereas extraction of perchloroethylene in the field-scale experiment was not successful... 

Information obtained from field-scale experiments conducted during the last decade on mobile water-tracer chemicals is not encouraging. Extensive vertical and lateral variability of water and chemical transport and retention parameters has created difficulties in testing laboratory scale models (11). Furthermore, a... 

D. J. "Size and Radiative Characteristics of Natural Gas Flares. Part 1 Field Scale Experiments." Chemical Engineering Research and Design 65, no. 4 (1987) 310-17. 

Releases of liquefied toxic or flammable gases often take place in aerosol form, consisting of vapor and liquid droplets of the released species, together with entrained humid air. This has been demonstrated in several laboratory and field-scale experiments (e.g., Koopman et al., 1986, Moodie and Ewan, 1990 Nolan et al., 1990 Schmidli et al., 1990 Nielsen et al., 1997). Aerosol phenomena may have a significant influence on the temperature and density evolution of the source term and on the subsequent heavy gas dispersion. In particular, the deposition of substance liquid droplets may, under certain conditions, cause a substantial decrease of concentration. 

The experiment conducted by the Rand Corporation in the late 1970s, designed as a large-scale experiment in order to overcome this methodological difficulty, is already a classic in the field of health economics.22 It consisted in allocating 16 different 3-5-year health insurance schemes at random to a broad sample of people distributed geographically in six different areas of the USA. The co-payment rates varied from 0 per cent to 95 per cent, depending on the scheme and the services provided. The data supplied by the... 

The experimentation in the field of gas cloud fires appears to be limited. The unique set of large-scale experiments that involve the release, dispersion, ignition, and combustion of flammable natural gas clouds in the open air is that with the code name Coyote. Coyote series trials conducted by LLNL in 1983 at California s Nevada Test Site, Nevada provided an integrated dataset for use in validation studies [64,65]. The objective of the experiments was to determine the transport and dispersion of vapors from LNG spills, and in addition to investigate the damage potential of vapor cloud fires. Transient simulations... 

Quantifying adsorption of contaminants from gaseous or liquid phases onto the solid phase should be considered valid only when an equilibrium state has been achieved, under controlled environmental conditions. Determination of contaminant adsorption on surfaces, that is, interpretation of adsorption isotherms and the resulting coefficients, help in quantifying and predicting the extent of adsorption. The accuracy of the measurements is important in relation to the heterogeneity of geosorbents in a particular site. The spatial variability of the solid phase is not confined only to field conditions variability is present at all scales, and its effects are apparent even in well-controlled laboratory-scale experiments. 

The vast majority of literature on quantifying transport processes has been considered in the framework of laboratory experiments. Field experiments, which often display fundamental differences in transport behavior relative to laboratory experiments, are inevitably subject to serious uncertainties, relating to initial and bonndary conditions, medium heterogeneity, and experimental control. A major aspect— and difficulty—lies in integrating laboratory and field measurements and upscaling small-scale laboratory measurements to treatment of field-scale phenomena. 

The field experiments from the Bet-Dagan site were used to test different theoretical models for field-scale chemical transport. One study expanded a simple column model for flow and transport in partially saturated soils (Bresler and Dagan 1983),... 

The analysis was limited in part by the scarcity of measurements, and clear discrepancies between measured and calculated values may be observed. As discussed in Chapter 10, tailing effects often are due to non-Fickian transport behavior, which was not accounted for in this model. Interestingly, the field-scale retardation coefficient values of the reactive contaminants were smaller by an order of magnitude than their laboratory values, obtained in an accompanying experiment. 

The results of a field-scale test at the Borden site are reported by Rivett and Feenstra (2005). This experiment used a DNAPL multicomponent system similar to that of Broholm et al. (2005), with the difference being that the contamination... 

The technology has been used during bench-scale experiments and field-scale demonstrations. The technology is available for licensing through SUNY, Oswego, and is commercially available through Environmental Oxidation Systems, L.L.C. 

Acoustically enhanced remediation (AER) is an in situ remediation technology that uses acoustic excitation fields (AEFs) to enhance rates of fluid and contaminant extraction from a wide variety of soil types. Bench-scale proof-of-concept tests have been completed and were followed by larger scale laboratory experiments. According to the vendor, a field-scale proof-of-principle step has been planned. The vendor indicates that this technology is currently commercially available however, it is uncertain whether these field-scale tests have occurred. 

Vilks, P., Frost, L. H. Bachinski, D. B. 1997. Field-scale colloid migration experiments in a granitic fracture. Journal of Contaminant Hydrology, 26, 203-214. 

In the field, o-xylene is also observed to degrade with nitrate in all but a few of the reported cases (Table 3.5). No o-xylene degradation was observed in either microcosms (Ball Reinhard, 1996) or in field-scale bioreactors by Ball et al. (1994). However, the removal of this substrate was apparent in a field injection experiment. Since the sediments were initially sulfate reducing, there may have been an adaptation period for substrate depletion with nitrate that was longer than the 40 and 60 day incubation periods associated with the microcosm and bioreactor study, respectively. As noted for the other alkylbenzenes, the second field study not showing anaerobic o-xylene degradation (Acton Barker, 1992) was compounded by the presence of acetylene in the experiment. 

Most laboratory experiments demonstrating the utility of EO transport of organic compounds were conducted with kaolinite as the model clay-rich soil medium. Shapiro et al. (1989) used EO to transport phenol in kaolinite. Bruell et al. (1992) have shown that TCE can be transported down a slurry column by electroosmotic fluid flow, and more recently, Ho et al. (1995) demonstrated electroosmotic movement of p-nitrophenol in kaolinite. Kaolinite is a pure clay mineral, which has a very low cation exchange capacity and is generally a minor component of the silicate clay mineral fraction present in most natural soils. It is not, therefore, representative of most natural soil types, particularly those which are common in the midwestem United States. The clay content can impact the optimization and effectiveness of electroosmosis in field-scale applications, as has recently been discussed by Chen et al. (1999). 

Table 8. Field scale study - Ecotoxicity of accumulated percolates of a municipal solid waste incinerator bottom ash (BA) and a slag from a second smelting of lead (2SL) from field experiments and their corresponding waste PEEP index values (see Section 5.6 for the detail of calculations).

Much of the literature is based on experimental data with similarly sized particles and observations of the speed required to keep particles in motion with at most 1 or 2 sec of rest on the bottom of the tank. This is done by visually observing solids in a transparent tank. This, of-course, means that relatively small-scale experiments are conducted and that this particular criterion cannot be used for studies in large-sized tanks or in field tests. 

The interaction of dispersing clouds with vapor fences is a complex physical process. When a flow meets an obstruction, turbulence levels are increased downstream because of vorticities introduced into the flow field, and increased velocity gradients are induced by flow momentum losses. Detailed modeling of such a process is very difficult and requires a combination of small-scale experiments and computational fluid dynamics. 

Other photocatalytic disinfection experiments (not shown here) were carried out and in all cases EDT24 was reached before 3h of phototreatment (Rincon and Pulgarin 2004). In preceding works, a residual disinfection effect was observed at laboratory and field scale after solar photocatalytic treatment (Rincon and Pulgarin 2004a, b, 2005, 2007b, c). 

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