High concentration of PAH compounds including oil based hydrocarbons, up to the level of 1,000 ppm (parts per million) had been discovered at the site. The source of the pollution is unknown.
A large area, more than one hectare at the railway yard is polluted from one to two meters below the ground level. Ground water level at the location varies between two to three meters below the ground level. To not to disturb the business-critical logistics traffic at the railway yard, a small area was allocated for EKOGRID in-situ remediation pilot.
Vertical electrodes, nine steel rods of two meters in length were installed into the ground. The grid of electrodes was coupled together by horizontal electrodes made of steel wire of 8 mm in thickness. The grid was controlled by one control unit.
The EKOGRID control unit at the site in Sao Paolo was monitored remotely from the Eko Harden Technologies office. The system provides information about the current and voltage levels and the pulse shape. Automatic alarms are sent to the office in case of faults such as power outage.
The performance of the EKOGRID installation was analyzed through soil sampling, which is a common practice in in-situ projects. Despite a small test area, the installation was monitored by taking samples from seven locations at the pilot area. Samples at four occasions were taken and analyzed at a local accredited laboratory.
EKOGRID electro kinetic oxidation solution cleaned the contaminated soil at the railroad yard in Sao Paolo extremely fast. Concentrations of total petroleum hydrocarbons (TPH) and PAH compounds were reduced below the level detectable at the laboratory. Within just three months the level of contamination practically reached zero.
Compared to a traditional dig and dump mass transfer method, the railway business operator saved time and avoided the costs due to soil transportation and stoppages in rail traffic!