The former Mobile Repair Department was located at the southern end of the Infilled Lands, near Ferry Street (Figure 5-1). The site is bordered to the north by the Scrap Storage Area, to the east by the West Side Road, and to the west by general disposal area of the High Dump.

Over several decades, locomotives and motor vehicles were repaired, maintained and fueled in this area. The Mobile Department building contained eight repair bays, most of which had service pits for accessing the underside of the vehicles. Extensive storage, handling and use of petroleum fuels, lubricants and solvents took place in this area, giving rise to the potential for soil and groundwater contamination in this area.

The Mobile Department, constructed in the 1920s, was formerly referred to as the roundhouse as this was a generic term for a locomotive repair shop. Motor vehicles such as large trucks and front-end loaders were also serviced in this building. Prior to its demolition in 2001, the concrete floor and service pits were heavily stained with oil and grease from years of maintenance activities.

Records indicate that at least two underground storage tanks were once located on this parcel. Specifically, two 9000-litre steel tanks, installed around 1970, were removed in 1996. The tanks stored gasoline and diesel fuel, and the same records show that contamination was associated with these tanks. Although some contaminated soil was removed from the site at this time, no confirmatory sampling was performed.

Currently two aboveground motive fuel storage tanks, both equipped with dispensers, are located at the former Mobile Department site. The gasoline and diesel tanks remain in use to service site vehicles. Both tanks have double steel walls. No significant environmental concerns are associated with these tanks. An aboveground waste oil tank was cleaned and removed from the site in 2001.

The Old Yard Office	Three other buildings were once located to the south of the former Mobile Department building, including a tool shed, a paint shop, and the former Liquid Air plant. The latter was constructed before 1953 and was demolished in 1998. The plant ceased operation in the 1970s when the new Liquid Air plant was constructed adjacent to Victoria Road on the east side of the plant.
The “Boneyard” occupies the northwestern portion of the area. Derelict equipment, tires, vehicles and machinery are stored here, and petroleum hydrocarbon soil staining was observed in this area, likely resulting from the disposal of equipment. Several railway tracks are located throughout this area, many of which have been abandoned and covered with slag for many years. Environmental issues of concern associated with the rail tracks include creosote rail ties and potential contaminated soil under and adjacent to the tracks. In the past, used oil was often used for dust suppression on roadways on the steel plant property. A drum storage area was observed adjacent to the DTPW-owned Substation #1, located to the north of the former Mobile Department yard. Approximately 100 drums are stored in this area. Many of the drums are on their side and heavy petroleum hydrocarbon soil staining was observed in this area. In addition, miscellaneous waste debris was observed in this area including domestic garbage, oily rags, oil filters, hoses, wire, wood and metal. No buildings are currently located in this area, but the #1 Substation may include PCB-containing equipment, mercury-containing equipment and lighting, and petroleum storage. A second substation was formerly located to the west of the former Mobile Shop. While all structures and equipment have been removed from this area, impacts may remain in the soil and/or groundwater. While no records were discovered, herbicides were often used to suppress vegetation in transformer compounds.
Interior of the Mobile Shop	The majority of open space in this area is covered with granular materials. Slopes at certain locations show signs of surface erosion. Overland drainage in the area may present the possibility of siltation and sediment impacts to receiving waters.

Potential environmental issues related to soil and groundwater in SCU 24 consist of petroleum hydrocarbons, heavy metal, PCB, herbicide, and solvent impacts as a result of historic on-site activities. In addition, PAHs, PCBs, HNCs and heavy metals impacts associated with Tar Ponds contamination may have infiltrated groundwater and subsurface soils. Coal tar-impacted 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.