Soils field tests

Biodegradation aqueous aerobic t,/2 = 504-14200 h, based on unacclimated aerobic river die-away test data and soil field test data (Lichtenstein et al. 1971 quoted, Howard et al. 1991) ... 

Prevention of Soil Crusting. Acid-based fertilizers such as Unocal s N/Furic (a mixture of urea with sulfuric acid), acidic polymers such as FMC s Spersal (a poly(maleic acid) derivative originally developed to treat boiler scale) (58), the anionic polyacrylamides described previously, as weU as lower molecular weight analogues such as Cytec s Aerotil L Soil Conditioner, have all been used successfully in at least some circumstances to prevent the formation of soil cmsts. It is difficult to prove benefits in the laboratory, and field tests may give variable results depending on local weather conditions. 

Table 4-2 Evaluation of field tests [11] by class of soil (average standard deviation). ...

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. ... 

Approximate allowable bearing pressures on sedimentary rock and soils may be taken from Table 2-31 [1 and 37]. Where questionable surface and subsurface soil conditions exist allowable bearing pressures can be determined with the aid of field sampling, field tests (both surface and subsurface through borings), and laboratory tests. 

Oxidation-reduction potential Because of the interest in bacterial corrosion under anaerobic conditions, the oxidation-reduction situation in the soil was suggested as an indication of expected corrosion rates. The work of Starkey and Wight , McVey , and others led to the development and testing of the so-called redox probe. The probe with platinum electrodes and copper sulphate reference cells has been described as difficult to clean. Hence, results are difficult to reproduce. At the present time this procedure does not seem adapted to use in field tests. Of more importance is the fact that the data obtained by the redox method simply indicate anaerobic situations in the soil. Such data would be effective in predicting anaerobic corrosion by sulphate-reducing bacteria, but would fail to give any information regarding other types of corrosion. 

Finally, it should be added that the extensive field tests made in the United States indicate that buried steel rusts less and less rapidly as time goes on, both as regards general attack and pitting. This can be illustrated by the typical results shown in Fig. 3.5. Field tests made in British soils by BISRA have not, however, exhibited the same tendency in these rusting has been roughly proportional to the duration of burial. 

The results of these experiments have been considered by the Joint Committee for the Co-ordination of the Cathodic Protection of Buried Structures and, in view of the various types of buried structures concerned and the circumstances in which field tests are conducted, the Committee decided not to amend its provisional recommendation that when cathodic protection is applied to a buried structure the maximum permissible potential change in the positive direction on a nearby pipe or cable should be 20 mV. If there is a history of corrosion on the unprotected installation no detectable positive change in structure/soil potential should be permitted. These criteria of interaction have been adopted in the British Standard Code of Practice for Cathodic Protection . 

The precautions generally applicable to the preparation, exposure, cleaning and assessment of metal test specimens in tests in other environments will also apply in the case of field tests in the soil, but there will be additional precautions because of the nature of this environment. Whereas in the case of aqueous, particularly sea-water, and atmospheric environments the physical and chemical characteristics will be reasonably constant over distances covering individual test sites, this will not necessarily be the case in soils, which will almost inevitably be of a less homogeneous nature. The principal factors responsible for the corrosive nature of soils are the presence of bacteria, the chemistry (pH and salt content), the redox potential, electrical resistance, stray currents and the formation of concentration cells. Several of these factors are interrelated. 

Two civil engineering operations require particular attention when soil corrosion tests in the field are required. These are (1) the use of reinforced earth structures in which the corrosion conditions will differ from those at... 

Ho SV et al. (1999) The lasagna technology for in situ soil remediation. 2. Large field test. Environ Sci Technol 33 1092-1099. 

Earlier in this paper studies were reported that indicated correlation of the molecular structure of the compound with bioactivity in seed germination in laboratory tests, as compared to tests performed in the field, offer distinct advantages. Most of what we know on this subject was obtained from laboratory test procedures. Results from field tests are also dependent upon the stability of the compound and physical factors such as solubility and adsorption in the soil. 

Field test work with technically pure gamma isomer of hexachlorocyclohexane has been extensive and involved and is being continued. It was necessary to know such factors as insecticidal value in field applications as compared to other insecticides, as well as residual life, residue from the poison standpoint, and residual taste or odor factors. These factors have been worked out on numerous crops and some of the results are dealt wTith in this paper. Because the pure gamma isomer was found to be effective on insects in the soil as well as on insect infestations on plants, its residual life in soil of all types and effects on tuber and root crops were also of major importance. 

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. 

Surfactants have been widely used to reduce the interfacial tension between oil and soil, thus enhancing the efficiency of rinsing oil from soil. Numerous environmentally safe and relatively inexpensive surfactants are commercially available. Table 18.6 lists some surfactants and their chemical properties.74 The data in Table 18.6 are based on laboratory experimentation therefore, before selection, further field testing on their performance is recommended. The Texas Research Institute75 demonstrated that a mixture of anionic and nonionic surfactants resulted in contaminant recovery of up to 40%. A laboratory study showed that crude oil recovery was increased from less than 1% to 86%, and PCB recovery was increased from less than 1% to 68% when soil columns were flushed with an aqueous surfactant solution.74-76... 

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... 

A comprehensive program of testing soil liner materials will involve both laboratory and field tests. Field tests provide an opportunity to permeate a larger, more representative volume of soil than do laboratory tests. A field test is also more comprehensive and more reliable. 

The clay liner at Keele Valley was built very carefully with strict adherence to CQA. The laboratory and field values are the same because the liner is essentially free of defects. Lab and field values differ when the soil liner in the field contains defects that cannot be simulated accurately on small specimens. If the soil is homogeneous, lab and field tests should compare very well. 

Following rapid field testing, samples of the potentially contaminated air/water/ soil will be collected for potential lab analysis. The decision to send samples to a lab for analysis should be based on the outcome of the threat evaluation. If the threat is determined to be credible, then samples should be immediately delivered to the lab for analysis. The analytical approach for samples collected from the site should be developed with input from the supporting lab(s), based on information from the site characterization and threat evaluation. 

Two types of kits are discussed in this section, sample collection kits and field test kits. Sample collection kits will generally contain all sample containers, materials, supplies, and forms necessary to perform sample collection activities. Field test kits contain the equipment and supplies necessary to perform field safety screening and rapid field testing of the air, water, and/or soil. Sample collection kits will generally be less expensive to construct than field test kits. Sample collection kits can be pre-positioned throughout a system, while the more expensive field kits may be assigned to specific site characterization teams or personnel. 

A soil infiltration test was devised to screen a large number of compounds within a limited time span. The amounts used are far in excess of quantities used in field application. A 5% diamide solution in isopropanol, 15 mL, was added to 50 g soil, air dried overnight, and then placed in a vacuum oven at 50° for 1 hr to remove traces of isopropanol. The treated soil, 10 g, was placed in a 25 X 500 mm glass chromatographic column with a coarse porosity fritted disc on top of a detachable adapter base. The soil was tapped down lightly with a wooden dowel to a depth of 12 mm in order to prevent channeling. Forty-five cm of water covered the soil. The period required for 200 ml distilled water to penetrate through 10 g of treated soil was recorded as the infiltration time. The test was arbitrarily discontinued after 2 weeks. 

A field test for the detection of TNT in contaminated soils (e.g., near ammunition plants) was based on the color reaction between TNT and alkalis (the Janowski reaction [7]) [26]. A few milligrams of the suspected soil are placed on filter paper and sprayed with 1 M NaOH acetone (1 1). A red color indicates the possible presence of TNT. Detection limits were reported to be 2-50 mg of TNT per 1 kg of soil, depending on the type of soil. The same group [55] used the oxidation of DPA in concentrated H2SO4 as the basis of a field test for nitrate esters and nitramines in soil. 

The MetPAD test kit (Group 206 Technologies, Gainesville, Florida) has been developed for the detection of heavy metal toxicity. It has been used to determine the toxicity of sewage water and sludge, sediments, and soil [41]. The test is based on the inhibition of (3-galactosidase activity in an Escherichia coli mutant strain. Performance of the test does not require expensive equipment and it is therefore easily applied as a field test. 

Certain tree species such as Betula pendula and Picea abies fail to develop in association with heather, Calluna vulgaris (40. 1). This apparently results from the production by heather of an allelochemical toxic to growth of mycorrhizae of Betula and Picea. Fruticose soil lichens are often allelopathic to the growth of mycorrhizae and forest tree seedlings also (42). Removal of reindeer moss (a lichen) in field tests resulted in accelerated growth of pine and spruce. 

---