Tar Ponds Sediment Sampling and Studies Under Way
TRANSPORTATION/PUBLIC WORKS--Tar Ponds Sediment Sampling and Studies Under Way
The sediment samples that will lead to the choice of final cleanup solution for the Sydney tar ponds are now being collected.
About 2,500 litres of sediment is being removed from the south pond area. These samples will be stored in sealed drums and shipped to laboratories throughout Canada for extensive analysis.
The companies interested in showing how their technologies can clean up the tar ponds will conduct a series of laboratory bench- scale demonstrations on these sediments. This process will show which technologies are capable of treating the complex mix of contaminants in the tar ponds. The results of the bench-scale demonstrations -- expected in early 2002 -- will be an important part of the Remedial Action Evaluation Report. That report will evaluate these technologies, as well as others that may be appropriate, and is a major step in designing the final cleanup plan.
"The sediment sampling and bench-scale demonstrations are major milestones in progressing towards the tar ponds cleanup," said Dan Fraser, chair of the Joint Action Group. "The results from the bench-scale testing will give the community a clearer picture of which technologies can treat the tar ponds contaminants effectively."
An excavator will be used to collect the samples in the south pond. The procedure is designed to be carried out as safely as possible and with minimum disturbance to the site.
"We're taking every precaution during the collection, storage and shipment of the sediment samples," said Jim Wilson of Vaughan Engineering Ltd., the Sydney-based firm overseeing the work. Air monitoring will be carried out during the sampling to help safeguard workers and the community. The samples will also be stored and shipped under regulated procedures for handling hazardous waste.
Eight consortia, based in Canada and the United States, are interested in conducting the bench-scale demonstrations. They are: UMA Industrial Processes Ltd.; Colmac Resources Inc.; IT Corp. (two proposals); TDEnviro Inc.; DRL-UXB Canada Joint Venture; Science Applications International Corp. (SAIC); Grace Bioremidiation tech/URS Corp.; and AMEC Inc.
The sediment sampling and bench-scale demonstrations are part of the $62-million federal-provincial-municipal agreement that covers all of the preparatory studies and work leading to the selection of the final remediation plan.
The Sydney tar ponds contain about 700,000 tonnes of contaminated sediments left over from a century of steelmaking and other industrial activity.
NOTE TO EDITORS: A backgrounder on the technologies being tested under bench-scale demonstrations is available below.
BACKGROUNDER--Muggah Creek Remediation Project
Technologies Being Tested under Bench-scale Demonstrations
Thermal desorption: This technology involves gradually heating the material to hit the boiling points of the various contaminants. Once vaporized and condensed, these contaminants can be separated and treated. Lower temperatures are used on organics found in sewage waste or petroleum. Hotter temperatures are applied to polycyclic aromatic hydrocarbons (PAHs) or polychlorinated biphenyls (PCBs).
Pyrolysis: Contaminated waste is dried, starved of oxygen and heated in a pressurized kiln or hearth to over 430 C. This causes organics like PCBs and PAHs as well as dioxins (chemical compounds that can result from industrial combustion involving chlorine) to break down into gases which can be recovered and treated. What's left includes water and oil, which can also be treated, along with a solid residue of carbon and ash for disposal.
Incineration: A widely used technology in which a fuel source and oxygen are used to heat waste material to temperatures up to 1,200 C. That's enough to destroy contaminants, leaving ash residue and off-gases which can then be separated, treated and disposed of safely.
Plasma: Contaminated material is placed in an electric arc which produces temperatures as high as 28,000 C, instantly destroying organic contaminants. Any metals melt and then cool into a solid for recycling or disposal.
Solvent extraction: A solvent is used to dissolve organic contaminants so they can be separated from waste material. The solvent can be recycled, while the contaminants are treated and disposed of safely. This process is typically used in combination with other technologies.
Bioremediation: Micro-organisms such as bacteria, fungi or yeast are used to naturally break down organic contaminants into harmless substances. It's a very slow process that's often sped up by boosting levels of oxygen and nutrients.
Stabilization/solidification: Contaminated material is hardened using cement based chemicals and other reagents into a mass so solid that water can't penetrate it, and contaminants can't leak out.
Soil washing: Contaminated material is immersed in a water-based solution with additives to dissolve or concentrate contaminants which can then be siphoned off and treated. This process works on metals, fuels and other organic contaminants. Water used in the process is treated before disposal.
Acid Extraction: Contaminated material is washed with an acid which extracts the heavy metals into solution. The metals are then recovered and treated and the acid recycled.