Enviro-Klean Remediation Group Inc (EKRG) is a manufacturers of asphalt plants began modifying their equipment to remediate hydrocarbon contaminated soils. The process was effective, however, fuel consumption and undesirable air emissions presented significant challenges. As a result, a group of engineers joined forces under the name Enviro-Klean and began to explore alternate soil heating methods.
History: 1980's to Present
Back in the 1980’s, manufacturers of asphalt plants began modifying their equipment to remediate hydrocarbon contaminated soils. The process was effective, however, fuel consumption and undesirable air emissions presented significant challenges.
As a result, a group of engineers joined forces under the name Enviro-Klean and began to explore alternate soil heating methods.
They created the unique Enviro-Klean soil curtain design, which has been modified and improved through 4 generations.
Each new enhancement has increased the throughput, reduced energy consumption and improved air emissions. Today’s model, the KM-4, is a testimony to the company’s unceasing pursuit of perfection.
Certified Engineering & Manufacturing
Enviro-Klean equipment is engineered and manufactured in North America, and meets UL, CSA and European CE standards.
All machine components are designed for years of productive service. (The KM-2 pictured on the right was built in 1994 and is still in operation.) The drives and gear boxes used to power the screw conveyors and augers are top-of-the line Eurodrive and Baldor. The electronics are Siemens. The fuel system is Eclipse. The heavy-duty trailers feature air-ride suspensions. Enviro-Klean is committed to providing competitive, state-of-the-art thermal remediation equipment that meets or exceed the toughest environmental standards world-wide.
The Eniro-Klean technology can process a wide range of soil types. Some soils will be easier than others to work with and will thus 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, plus a “clay” component.
Clay soil can prove to 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 material 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 as these fines tend to make their way into the filtration system at increased volumes, causing overloading of the filters 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 airstream. Usually a by-product of organic clay and sometimes mixed with fine sand, silt is any soil particles that can pass at least 50% through a 200 mesh screen. 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, and therefore the more it will cost to operate.
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 pre-treatment system. Sometimes, 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 time will make a major difference. Another method is using a 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. The KM-4 includes a trommel with the feed system.
Type/Level of Contaminant
The KM-4 is designed to remove hydrocarbons from soil. The processor is designed with maximum heat-to-soil contact near the bottom of the soil boxes and the heat diminishes as it contacts soil in its rise upward as it get pulled by the induction fan.
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, thus increasing its 'throughput.'
Soils will quite often contain hydrocarbons ranging from C10 to C40, the latter being to upper range of hydrocarbons allowable through the KM-4. A contractor 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 these factors 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 absolute worst-case scenario and therefore the throughput would be in the range of 12-15 tons per hour, (tph). With more favourable conditions, the throughput could reach 30 tph or more.
The five factors: soil type, moisture content, contaminant type, contaminant level and clean-up criteria all vary from project to project. Therefore, one can see the effect on the operating cost when looking at a Soil Profile can be much different from site-to-site also.