Our Process for Cleaning Contaminated Soil
Description of Unit
The Thermally Enhanced Soil Vapor Extraction (TEVE) system is an onsite technique for the removal and destruction of volatile organic compounds (VOCs) and semi-organic compounds (SVOCs) from excavated soil. The TEVE process consists of a soil pile constructed with excavated soil, air distribution piping and an impermeable membrane cover. The major components of the system are a vapor blower, an air recovery blower, a burn chamber and a catalytic reactor bank. The entire unit is custom built into a twenty-four foot (24â) enclosed trailer.
Scope of Work
An impermeable membrane liner with a perimeter curb is placed on the ground. Contaminated soil is placed on the liner. The initial lift of soil is approximately one foot (1) to three feet (3) thick. Heated air distribution piping is then positioned on top of the initial soft lift. The second lift layer is approximately three feet (3) to four feet (4) of contaminated soil. Heated air distribution piping is then positioned on top of the second soil lift. The final lift of contaminated soil is approximately one foot (1) to three feet (3) thick. The treatment soil pile typically contains approximately one-thousand (1,000) tons of contaminated soil. The dimensions of the soil pile are typically forty feet (40) wide by eighty feet (80) in length.
On top of the soil pile, vapor recovery piping is installed to collect the emissions that emanate from the soil pile. The soil pile is then covered with the same impermeable liner material. The cover serves to limit the emission of VOCs, prevent infiltration of moisture and provide a dust control measure.
Heated air is blown into the soil pile, passing through the soil, volatizing the contaminants and exiting the pile through the vapor extraction piping.; The collected vapors are then passed through a burn chamber where contaminant destruction occurs.
The burn chamber operates at 1,800 degrees Fahrenheit (oF) with a residence time of 0.5 seconds. From the burn chamber, the air is re-injected into the soil pile. Ten percent (10%) of the air stream is exhausted through three catalytic oxidizers manfolded in parallel in a four inch (4″) exhaust stack, or other appropriate scrubbing device further assuring that contaminants or particulates are not exhausted to the atmosphere.
Controlled heated air is injected into the soil pile at a temperature ranging up to 750F and at 3,500 cubic feet per minute (CFM). Based on these operating conditions, the soil temperature can be elevated from ambient temperature to between 150F and 500F. The soil is treated at these conditions until cleanup objectives are met. Cleanup objectives are typically accomplished in four to seven days.
Confirmatory soil samples are collected and analyzed to verify that remediation objectives have been met. Also, continuous air monitoring of the extracted vapors ensures that proper destruction is achieved and that air emission limits for the exhaust are not exceeded.
Pilot Process Test
TEVET has constructed a bench scale pilot unit to determine the efficiencies of contamination removal. Samples taken from the field can be tested to establish operating settings to insure maximum results and the best back end scrubber technology.