Excavation limited

Applicability/Limitations. In-situ treatment can be used when it is uneconomical to haul or when infeasible or uneconomical to dig or pump the contaminated waste matrix for treatment in a reactor. This approach should be used whenever excavation or removal causes an increased threat to human health. It can reduce the cost of a remediation program. Because chemicals are applied to the contaminated waste matrix, specifically soil and groundwater, a potential exists for reaction with the soil. Permeability problems can occur as the result of precipitate formation. This can result in inadequate mixing of the contaminant with the treatment chemical. Gas generation may also occur. 

Remediation activities at American Thermostat included the excavation and thermal treatment of over 13,000 cubic yards of soil and sediments contaminated primarily with perchloroethylene, trichloroethylene, and solvents. The soil was excavated and treated using a thermal treatment unit called the low-temperature enhanced volatilization facility (LTEVF). The performance test for the site s thermal unit had just been completed at the time of the inspection, so there was limited activity. 

The applications and limitations of passive gas control systems must also be understood. They can be used at virtually any site where there is the capability to trench or drill and excavate to at least the same depth as the landfill. Limiting factors could include the presence of a perched water table or rock strata. Passive vents should generally be expected to be less effective in areas of high rainfall or prolonged freezing temperatures. 

Figure 16.8 shows an active perimeter gas extraction system. Active systems can be used at virtually any site where there is the capability to drill and excavate through the materials in the action area to the required depth. Limiting factors of active systems include the presence of freestanding leachate (i.e., saturation) or impenetrable materials. Active perimeter gas control systems are not sensitive to freezing or saturation of the surface or cover soils. 

Such facilities are deemed to include any dam or other structure serving to contain, retain, confine or otherwise support such a facility, and also to include, but not be limited to, heaps and ponds, but excluding excavation voids into which waste is replaced, after... 

Obtundents are the agents which are used to either diminish or eliminate the dentine sensitivity to make the excavation painless. But due to the availability of local anaesthetics e.g. xylocaine for painless excavation, the use of obtundents is very limited. 

Janite. A large grain, black blasting powder impregnated with NG. It was used to a limited extent for excavation work on the Isthmus of Corinth in Greece Ref Daniel (1902), p 386... 

With ex situ treatment of contaminated soils, a controlled environment for soil treatment can be maintained- With mixing, nutrient addition, aeration, and other environmental controls, mass transfer rates that typically limit in situ bioremediation can be greatly increased. Of course, the disadvantages of ex situ bioremediation are the costs of soil excavation and reactor operation. Thus, ex situ bioremediation is favored by localized, shallow soil contamination. 

In an attempt to evaluate the applicability of LA-ICP-MS to the study of human bone, we analyzed teeth and bone obtained from seventy-six individuals recovered during excavation of the Paloma archaeological site in central Peru. Paloma was occupied from approximately 3830-3730 B.C. and is located along the coastal plain of central Peru (36, 37). The only moisture this area receives is in the form of dense fog which is deposited on the landscape between June and December. Consequently, inhabitants of the site would have had limited access to terrestrial food resources and would have greater dependence on marine resources from the nearby ocean for the majority of their nutritional requirements. 

Excavated soil suspected of containing lead has been stockpiled. We may use this soil as backfill if the mean lead concentration is below the action level of lOOmg/kg. To decide if the soil is acceptable as backfill, we will sample the soil and analyze it for lead. The mean concentration of lead in soil will represent the statistical population parameter. The theoretical decision rule, the baseline and the alternative conditions, and the null and alternative hypotheses have been stated in Examples 2.1 and 2.2. The assigned probability limits are a —ft — 0.05. This means that the false acceptance error rate is 0.05. The probability of making a correct decision is 0.95 or the confidence level is 95 percent. 

We must remember that entering a deep excavation might not be safe. According to the United States Occupational Health and Safety Administration (OSHA), confined or enclosed space means any space having a limited means of egress, which is subject to the accumulation of toxic or flammable contaminants or has an oxygen deficient atmosphere. Confined or enclosed spaces include, but are not limited to, storage... 

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