Slag from the steel making process has been produced at the Sydney Steel Plant since 1900. Reports indicate that the annual output by 1954 was approximately 300,000 tonnes per year. Historically, slag was dumped into the Muggah Creek estuary resulting in significant changes to the shoreline of Muggah Creek and the South Arm of Sydney Harbour (Figure 5-2).

An area of slag disposal and waste disposal is referred to as the “High Dump” and is located west of the plant area, between the Scrap Storage Area and Muggah Creek. For the purposes of this study, the High Dump has been defined as shown in Figure 5-1, and occupies approximately 10 hectares, or 15 percent of the infilled land.

The High Dump is the most visible result of filling operations, reaching a height of 30 metres at its peak. Prior to 1989 dumping at the SYSCO site was not monitored, and large quantities of waste materials were disposed on the High Dump, including derelict equipment, demolition debris, office waste, wastewater sludge, petroleum debris, varnish, waste oil, storage tanks and other wastes of unknown quality. Interview responses regarding the High Dump invariably included the phase “anything imaginable”.

Other process wastes such as Mill Scale (a carbonaceous material that flakes off the steel blooms in the Reheat Furnace), blast furnace flue dust, caster slag, and open hearth slag were also disposed in the High Dump at one time or another. Since 1989, an effort was made to segregate waste disposal, and divert inappropriate materials from the High Dump.

The Industrial Approval for the site contains a stipulation that calls for SYSCO to prepare a plan to address the cleanup of “hydrocarbon contaminated sludge on the high dump”. While efforts were made to divert continued disposal of such materials in the High Dump, a comprehensive remedial plan was not implemented.

Sediment from the process sewer located immediately south of Ferry Street, was periodically dredged from the line (Section 5.3.3). The resulting sediment was excavated and removed to the High Dump for disposal. While testing of the sewer lines in 1993 indicated that the sewer line sediment did not contain PCBs, existing PCB contamination in the Tar Ponds may have been removed coincidentally and deposited in with the sewer line sediment in the High Dump. The potential, therefore, exists that sediment with low concentrations of PCBs has been deposited in the High Dump at some point.

The results of testing performed by JDAC in 2000/2001 indicate that three borehole locations, MCES-001-MWB, MCES-002-MWB, and MCES-007-MWB are located within this area. Soil samples collected from these boreholes exceeded the CCME industrial guideline values for specific heavy metals (arsenic, chromium, thallium and vanadium), EPA 625s (semi-volatile compounds such as naphthalene), PAHs, HCNs, and EPA 624 (solvent-type compounds).

One surface soil location, MCES-001-SS is also located in this area. The surface soil collected from this location exceeded the CCME commercial guideline values for certain heavy metals (chromium and thallium). Many of the metals identified in the JDAC analyses were likely associated with slag fill. As discussed in Section 4.2, previous studies have been shown that metals in slag tend to pose a low level of environmental risk (CRA, 2001).

It is noted that the metals identified as exceeding guideline values in soil were not present in the groundwater at levels above the drinking water guidelines. This agrees with the results of leachate tests performed on many samples of blast furnace slag that indicate the highly immobile state of metals in slag.

Five monitor well locations; MCES-001-MWA (B), MCES-002-MWA (B), and MCES-007-MWB are located within this area. Groundwater from these wells exceeded the Canadian Drinking Water Quality Guideline values for iron, EPA 625, PAHs and HCNs. These contaminant groups are consistent with coal tar contamination. It is noted that the groundwater is not used as a source of potable water

Potential environmental issues associated with High Dump include fill and groundwater contamination associated with decades of uncontrolled waste disposal, including petroleum hydrocarbon, heavy metals, PCB, and solvent impacts to fill and groundwater. The potential also exists for PCB, PAH, HNC, and heavy metal impacts to be present as a result of contaminant infiltration from the Tar Ponds. Coal tar-contaminated sediment may be present , beneath the fill in this area.

Blast furnace slag was widely used as a fill material in this area. Various heavy metals are known to be present in blast furnace slag, but often in a highly immobile state. An important part of future environmental testing at this site will be the appropriate evaluation of heavy metal impacts in relations to their environmental risk.