Contaminated soils excavation

Felsot, A.S., J.K. Mitchell, T.J. Bicki, and J.F. Frank (1992). Experimental design for testing landfarming of pesticide-contaminated soil excavated from agrochemical facilities. Amer. Chemical Soc. Symp., 510 244-261. 

Composting by the addition of readily degradable hulking agents is also a useful option for relatively small volumes of excavated contaminated soil. 

Excavating and removing contaminated soil from the PCP/oil spill path and from the farm pond bottom ... 

Baird is the 20-acre site of a former chemical mixing and batching company. Poor waste disposal practices resulted in the contamination of groundwater, soil, the municipal water supply, and a brook adjacent to the site. Over one hundred contaminants, including chlorinated and nonchlorinated volatile organics, heavy metals, pesticides, herbicides, and dioxins, had been identified in site soil and groundwater. Remediation activities included soil excavation and incineration, and groundwater treatment (the audit focused on the soil excavation and incineration... 

The Brio refining site is approximately 58 acres in size and is the location of a former chemical production, recovery, refinery, and regeneration facility. The site includes closed impoundments into which hazardous substances were disposed in bulk, storage tanks, and approximately 1,750 drums of hazardous substances. Remediation activities included the excavation and incineration of contaminated soil, installation of protective liners around selected pits, and the installation of a groundwater extraction system adjacent to a gully. 

Soil surveys relating to construction work require samples from at least the depth of excavation water seepage may cause cross-contamination of land. Some guidelines for the classification of contaminated soils are summarized in Table 13.11 some materials are difficult to dispose of safely on land (Table 13.12). 

Biotic Transport Biotic transport can be defined as the actions of plants and animals that result in the transport of a radioactive material or other substance from a waste site to locations where it can enter pathways that may result in exposure to humans. Small mammals are ubiquitous and inhabit areas containing radioactive contamination or radioactive waste sites. Mammals inhabiting these areas may become contaminated with americium by consuming contaminated soil or plants and disturb americium-contaminated soil through their burrowing and excavating activities. These animals may therefore affect the distribution of americium within the waste site or transport americium to previously uncontaminated areas. In addition, small mammals may be consumed by animals higher in the food chain such as hawks and coyotes, which would add to the dispersal of americium from disposal areas. However, results of... 

In cases where in situ biological treatment cannot be applied, the contaminated soil is excavated and transferred to specially prepared areas where bioremediation can be carried out under well-controlled conditions. Some common ex situ biological methods are the landfarming technique and the biopile or biopit treatment options.32... 

It should be noted that early remedial actions for contaminated soil consisted primarily of excavation and removal of the contaminated soil from the site and its disposal at a landfill. SARA strongly recommends on-site treatment that permanently and significantly reduces the volume, toxicity, or mobility of hazardous substances, and utilizes cost-effective permanent solutions. The legislation prohibits land disposal of hazardous wastes unless U.S. EPA determines otherwise (as in the Hazardous and Solid Waste Amendments, HSWA). 

If an in situ treatment method is not feasible, a soil excavation and treatment method should be conducted. The soil excavation and treatment method is usually more cost-effective for small sites and shallow contamination. Before excavation, planning is needed regarding the following steps of the treatment, among others ... 

Avoiding the mixing of clean soil with the excavated contaminated soil, and uncontrolled mixing of incompatible wastes... 

Covering excavated contaminated soils to prevent water leaching and fugitive dust production... 

This alternative includes components of Alternatives 3 and 4 and introduces a thermal destruction component to address the TCE-contaminated soil. For the site remediation case shown in Figure 16.21, the lead-contaminated soil in Area 1 would be fixed and covered with a soil/clay cap, as described in Alternative 4. The groundwater would be addressed through pumping and treating, via an air stripper, as described in Alternatives 3 and 4. The TCE-contaminated soil in Area 2 would be excavated and treated on site by a thermal destruction unit comprisng a mobilized rotary kiln. 

It is estimated that approximately 15,290 m3 (20,000 yd3) of contaminated soil would need to be excavated and treated. The incinerator would be operated continuously (24 h/d, 365 d/yr), although... 

Community protection Risk to community not increased by remedy implementation, but, contaminated water may reach the residents within 1—3 yr Temporary increase in dust production through cap installation contaminated soils remain undisturbed Soil would remain uncovered during vapor extraction for 3-5 yr Temporary increase in dust production during cap installation Similar to Alternative 3 Fixation may result in dust and odor increase Soil would remain uncovered during incineration (about 1 yr) excavation and fixation would release dust and odors to the atmosphere... 

Soil vacuum extraction is cost-effective if the volume of contaminated soil exceeds 382 m3 (500 yd3), and if the contaminated area is more than 6 m (20 ft) deep otherwise, soil excavation and... 

This technique was developed by In-Situ Fixation Company for increasing the efficiency and rate of biodegradation in deep contaminated soils using a dual-auger system. Mixtures of microorganism and required nutrients are injected into the contaminated soils without any excavation. The injection and mixing effectively break down fluid and soil strata barriers and eliminate pockets of... 

Several preparation steps after soil excavation are required to achieve the optimum inlet feed characteristics for maximum contaminant removal ... 

If required, pump-and-treat groundwater remediation and/ or in situ bioremediation are options, but unlike with soil excavation, it may take years for contaminant concentrations to reach the agreed end point. The postclosure part of the closeout activities plan should contain a well-defined exit strategy for any necessary postclosure remediation, based on a sampling methodology that defines progress and determines when the end point is reached. 

One source estimated the cost of bioremediating explosives-contaminated soil to be 50 to 400 (1995 dollars) per cubic yard of soil treated. This estimate does not always include all indirect costs associated with treatment such as excavation, permits, and treatment of residuals. A U.S. Army study estimated that to treat less than 10,000 tons of contaminated soil, the cost would be 651 per ton for mechanically agitated composting, and 386 per ton for windrow composting (D17224H, p. 29). 

The U.S. Department of Energy s (DOE s) Los Alamos National Laboratory (LANE) conducted a cost analysis of the circulating fluidized-bed combustor based on the full-scale remediation of a former oil field on the Kenai Peninsula in Alaska. The LANE determined that the remediation cost ranged from 150 to 300 per ton when treating 20,000 to 50,000 tons of soil. For the treatment of 10,000 to 15,000 tons of contaminated soil, the cost ranged from 350 to 400 per ton. These estimates exclude the cost of excavation (D21225Z, p. 63). 

Excavation of contaminated soils is required and may cause the uncontrolled release of volatile organic compounds, if they are present. 

The in situ nature of this treatment also minimizes potential exposure to humans and the environment. Ex situ options like excavation require repeated worker handhng of the contaminated soil and increased opportunity for volatilization of contaminants (leading to off-site contamination). The off-gas stream generated as part of the SPSH process can be treated using conventional off-gas treatment technologies such as catalytic oxidation, thermal oxidation, condensation, and granular activated carbon (GAC). 

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