BATCH PILE TREATMENT
Batch Pile Treatment is one of the most commonly applied methods of Ex Situ
Thermal Desorption for the remediation of soils. When soil is heated, the organic
contaminants extracted from the soil pile or are destroyed in place.
Concentrations of chlorinated VOCs in soil can be reduced by almost 100% at
temperatures much lower than traditional “rotating kiln” arrangements. Diesel
and motor oil range petroleum hydrocarbon and most SVOC contaminants can
be removed by 99% or greater, and are most reliably remediated from the soil
matrix at temperatures between 200°C to 350°C by the following mechanisms:
Steam stripping of NAPLs up to and at 100°C,
Evaporation (volatilization) from 100°C to 350°C+,
Oxidation from 100°C to 350°C+, and
Pyrolysis (thermal decomposition in the absence of oxygen) from 100°C to 350°C+.
Batches ranging in volume from 10,000 m3 to 250 m3 have been successfully implemented in the United States and at several projects in Europe and Africa. Common applications have treated Pesticides, Di- & Trichlorobenzene, Heavy Oils, Paraffins, Dioxins, Jet Fuel, PCE and TCE.
GTR-O (Recuperative Oxidizer In-Well Vapor Treatment)
GTR-O is a method of using residual hydrocarbon contaminants in the extracted vapor stream as supplemental fuel to heat the treated soil. This thermal oxidization process removes [destroys] the contaminants from vapor.
GTR-O integrated into the thermal remediation project can provide the following benefits:
Energy Efficient: utilizes the thermal value of contaminants to heat soils and thereby reduces energy requirements
Simple & Cost-Effective: no large, external vapor treatment system is required
Scalable: for use at both large and small project applications
Batch Pile Treatment can also utilize conventional soil vapor extraction and treatment techniques when thermal oxidation may not be desired. Because the soil is heated indirectly (via conduction), a relatively small and simple vapor treatment system is required (compared to traditional direct-fired units).
Batch Pile Treatment Construction
The general, sequential phases of earthwork for a pile are shown in the picture series below. Generally, the soil is piled to the terminal height beginning on one end and then working to the opposite end of the pile, so that the loader and excavator do not drive over the wells already installed.
Construction of the batch pile generally follows these steps：
(1) The base area where the batches will be built are levelled for the pile to be constructed upon.
(2) A foundational drainage layer of gravel is placed along the base of the pile to isolate the pile from the ground and to drain liquids from the bottom of the pile into the extraction wells. New and/or existing concrete is generally used for the base layer, with slotted steel piping placed as drainage on top of the base layer.
(3) An excavator will pile the dirt onto the batch, one section at a time. Each level is sequentially installed to allow for the heating pipes and SVE pipes to be placed into the pile. A front loader may assist with soil placement.
(4) A crane or long reach excavator will be used to place the heating wells onto the dirt after the first layer has been formed. The crane will lift the pipes up using a spreader bar as shown.
(5) After the first row of heating pipes has been placed, more contaminated dirt will be placed on top of the heating pipes.
(6) After the dirt has been added, another layer of heating pipes will be placed on top of the dirt.
(7) This process will repeat until the pile has been completely built. The stages of the construction are shown below. Once one area is complete, the excavator will move back and begin the process again until the entire batch has been constructed.
(8) After the construction has been complete, insulation material(s) are placed along the sides and top of the pile mitigate heat loss to atmosphere.
Once the insulation has been placed, sheathing material is placed on the outside of the pile to keep rain from entering & cooling the soil.