COTTBUS MGP
Task: Develop a clean-up concept; treat and remove the tar
Time frame: 1 st pit, August-October 1996; 2 nd pit, August 1997-March 1998
Substances: 400 tons of tar residues, phenolic wastewater, contaminated soil, construction debris
Cottbus gas works
Clean-up and soil remediation at the SpreeGas manufactured gas plant (MGP) necessitated the emptying, material disposal, and clean up of two tar and ammonia pits. Substantial emissions were coming from the face of the pits that were 7 metres deep. Sheet piling had to be driven into the walls of the pits to protect the workers who would enter the pits for the cleaning operations.
Information
To prevent the steel-reinforced concrete pit covers from caving in during the pit clean-up operations, diamond cutting apparatus was employed to dismantle the covers section by section. The tar and construction debris was conditioned in situ using fine grained aerated concrete. Bulky items in the pits were pulled out and disposed of ecologically. "Pure" tar was mobilized and recovered by heating, moved to receptacles for further heating, and finally hauled away in tank trucks.
After the tar was removed, the pits were cleaned, sealed, and backfilled. Each step of the entire process was monitored continuously by local environmental authorities.