The Eniro-Klean technology can process a wide range of soil types. Some soils will be easier than others to work with, which will increase the throughput of the machine. The feed system on the machine will remove any rocks or chunks over 5cm (2 inches) in size using a trommel screen.
The specifications for the KM-4 for soil classification refer to ASTM: D2487, with the sub-categories GW (well-graded gravel with sand), GP (poorly graded gravel with silt, sand, cobbles and boulders), SW (well graded sand), and SP (poorly graded sand). Combinations of these soil symbols will indicate a mixture of conditions and are the most common occurrences in nature.
Clay soil can be a challenge, depending on the type of clay present, moisture retention, and tendency to lump into larger chunks. A certain amount of clay is usually present in most sub-soils, and the KM-4 can handle this mixture quite efficiently. The bottom line with clay - this material can slow the throughput down and make feeding the machine more difficult.
Some clay breaks down into very fine particles and becomes like powder - another concern for thermal remediation, since these fines tend to make their way into the filtration system at increased volumes, causing the filters to overload more quickly. To combat this potential problem, the KM-4 employs a multi-clone rather than a cyclone to remove 90% of the >50 micron particles from the air stream. Usually a by-product of organic clay and sometimes mixed with fine sand, silt is any soil particle that can pass through a 200 mesh screen at least 50% of the time. High percentages of silt should be avoided or these soils should be blended with a larger aggregate material to minimize their adverse affect on the equipment. The soil symbol for silt is ML, while clay is either CL, OL, CH or OH.
Hydrocarbons in a soil matrix tend to attach themselves to water molecules. The thermal processor of the KM-4 will evaporate the water as it vaporizes the hydrocarbons. The higher the moisture content, the slower the machine will process the soil, resulting in higher operation costs.
Moisture level in the soil can vary from one area to another by a considerable amount. The lower the moisture level of the soil, the less energy is required to boil the water out of the soil. The KM-4 specifications recommend that the moisture level not exceed 20%, or too much fuel is wasted dealing just with the water. Moisture levels below 15% increase the throughput capabilities greatly. Clays are especially bad when high moisture is present, because they tend to lock the moisture into their matrix and make it harder to remove.
A higher moisture content than desirable can often be remedied by an effective pretreatment system. Simply piling the soil up, covering it with tarps, and letting it drain for a period of time, coupled with turning the pile(s) several times will usually make a major difference. Another method is using the KM-4's trommel to aerate the soil before piling it up. This can also help to break up lumps in the soil and make it easier to process.
Type & Level of Contaminant
The KM-4 is designed to remove hydrocarbons from soil by designing the processor so that there is maximum heat-to-soil contact.
Hydrocarbons found in BTEX or gasoline contamination are much lower on the Carbon Chain than lubrication oils or Bunker C. The lower the carbon number, the less heat is required to vaporize the contaminants. The less heat that is required, the faster the machine can process it, thereby increasing its "throughput."
Soils will quite often contain hydrocarbons ranging from C10 to C40, the latter being the upper range of hydrocarbons allowable through the KM-4. Contractors must be aware of the Soil Profile prior to estimating the throughput and the amount of fuel required to process a given site. The Soil Profile will also indicate the LEVEL of contaminant(s), registered in parts per million, (ppm), or milligrams per kilogram, (mg/kg).
Both the type and level of contamination have a dramatic effect on the machine throughput, and therefore, on the cost for cleaning up a site. The KM-4 is capable of processing up to 25,000 ppm (mg/kg) of hydrocarbon contaminants to Carbon 40, (C40), however, this would be the worst-case scenario and would result in a throughput of approximately 12-15 tons per hour (tph). With more favourable conditions, the throughput could reach 30 tph or more.
The five factors of the Soil Profile - soil type, moisture content, contaminant type, contaminant level and clean-up criteria - all vary from project to project and will greatly effect the speed and the temperature of the KM-4. As a result, the Soil Profile must be careful assessed before estimating the operating costs of any site clean-up.