Soil capping

A Construction and Demolition landfill near Maalaea Maui caught fire on about 26 January, 1998. Landfill operators retained consultants to assist in putting out the fire. After repeated injections of liquid carbon dioxide and application of a soil cap, the fire was subdued to the point of no visible smoke as of early February 1998. Residents of the Maalaea condominium community condominiums, about one mile due south, had complained of... 

The U.S. EPA claims that the 30-year cost of treating lead at a 12-acre site using a phytoextraction technology would cost approximately 200,000. In contrast, the EPA estimated that excavation and disposal would cost 12,000,000, soil washing would cost 6,300,000, and soil capping would cost 600,000. For a 1-acre site with thick sandy loam, phytoextraction technologies are estimated to cost between 60,000 and 100,000. This estimate assumes treatment to a depth of 20 inches (D21292A, p. 17). 

Smith, E. D., Luxmoore, R. J. Suter Ii, G. W. 1997. Natural physical and biological processes compromise the long-term performance of compacted soil caps. In Barrier Technologies for Environmental Management Summary of a Workshop. National Academy Press, Commission on Geosciences, Environment and Resources (CGER), 79-88. World Wide Web Address http //books. nap.edu/books/0309056853/html/ http //www. infography.com / content/351566136978.html. 

At places in the Amazon the ferrasol is transformed over time to a podzol, a highly weathered, bleached, sandy soil capped by a thick, peat-like accumulation of litter on the top. Everything except quartz is rapidly leached out of the podzol soil including aluminum and iron. The latter are present initially as constituents of organic complexes, but they are not immobilized, because there is a relative lack of clay minerals for adsorption. 

The time periods that are required for recovery from possible phytotoxicity and physical disturbance are uncertain [89], In general, recovery of vegetation from physical disturbance in arid ecosystems can take hundreds of years [90], An estimate of the minimum time to recovery could be provided by the average age of the lost vegetation [90], It should be noted that the recovery of one ecological property can be impeded by restoration or reclamation of another. For example, the maintenance of impervious soil caps over a waste disposal site involves the removal (and therefore prevention of recovery) of deeply rooted vegetation and burrowing mammals [91],... 

The distribution and the nature of past, existing and potential pollution sources have also to be thoroughly established and assessed in light of the pollution vulnerability of the aquifer system concerned. A general appreciation of the reactive processes which may take place during contaminant transport, in ah sub-surface compartments (soils, cappings layers, unsaturated and saturated zones in aquifers, river beds,. ..) is required too. 

Within a risk-based remedial action framework, any of these three types of technologies may be considered for selection provided that they are effective at protecting human health and ecological resources. For a complex site, a remedial action may consist of multiple technologies (e.g., clay soil cap or monitored natural attenuation) representing one or more classes of remedial action (i.e., removal, decontamination, or control) that are combined in order to achieve all of the remedial action objectives. The user must research the effectiveness of each potential remedial action in order to determine whether the remedial action is capable of achieving all of the risk-based remedial action objectives. 

Chemicals such as cellulose xanthate can be sprayed on seedbeds to prevent soil capping. They enhance seedling establishment and do not affect herbicidal activity in the soil, but are very expensive. 

A fairly rough autumn seedbed is adequate for winter wheat and helps prevent soil-capping in a mild, wet winter. When soil-acting herbicides are used a fine seedbed is required. In a difficult autumn, winter wheat may be successfully planted in a wet sticky seedbed and usually it still produces a satisfactory crop. Spring wheat should only be planted in a good seedbed. 

Soil samples from the levels in which structure or pipes are to be laid are filled to the top of screw capped bottles, and bacteriological tests ire made within 24 hours. 

The atmosphere may be an important transport medium for many other trace elements. Lead and other metals associated with industrial activity are found in remote ice caps and sediments. The transport of iron in wind-blown soil may provide this nutrient to remote marine areas. There may be phosphorus in the form of phosphine, PH3, although the detection of volatile phosphorus has not been convincingly or extensively reported to date. 

The permeation of soil at the root-soil interface by mucilage from the root cap may affect structure, and it may oppose the damaging effects of compression and shearing, but little is known. Another suggested role is that the mucilage assists root-cap cells or acts in concert with them to decrease the friction between the growing root tip and soil (51) or, conversely, that the mucilage acts as a lubricant. 

M. C. Hawes, Living plant cells released from the root cap a regulator of microbial populations in the rhizosphere. Plant and Soil 729 19 (1990). 

In the laboratory, soil samples collected in the held are mixed thoroughly and reduced in size to laboratory samples. The air-dried soils are passed through a 2-mm sieve in order to remove stones and roots, then the water content of the soil is calculated after drying at 105 °C for 5h. If the analytical samples cannot be analyzed immediately after drying and sieving, they should be stored at about —20 °C in glass or Teflon bottles fltted with screw-caps. 

As the plastic liners are removed from the probe, they are capped on both ends, the appropriate labels affixed, and promptly placed in a freezer (an in-field sectioning technique used for further partitioning of the 0-15-cm core is described later in this section). By convention, red plastic caps are placed on top of the core (i.e., the end that was closest to the soil surface) and black caps are placed on the bottom. Use of the two-color capping system is important when the cores are sectioned at a later time. This approach is referred to as zero-contamination sampling and is the industry standard in field soil dissipation. 

The inner probe (with liner) is removed, leaving the outer retainer sleeve in the soil profile. While the liner Is still in the inner probe, a red cap is carefully placed on the top of the liner. Next, the probe is inverted, the A liner removed from the inner probe, and the bottom of the liner... 

Upper soil profile sample in liner with end caps... 

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