Project Description

The plant site is flat to gently rolling and slow draining. It is located in younger glacial deposits of Halton Till described as clayey silt till underlain by the Georgian Bay Formation of the Paleozoic Era of Upper Ordivician age comprising alternating green shale with limestone and dolomite. Glaciolacustrine clays and silts are underlying and interbedded in the glacial till. Modern river deposits of sands, silt as well as minor gravel and organic materials occur along nearby Mimico Creek.

The plant was the design and manufacturing facility for the famous Avro Aero jet.

An electromagnetic survey was carried out on a 5m grid over 5 acres to locate any buried metallic objects. The drilling of 53 exterior boreholes and 13 interior boreholes with several monitoring wells was conducted to collect 304 soil samples. The soils comprise low permeability clayey silt till at the south, and pervious layered clayey silt and sandy silt with glaciolacustrine deposits at the north. Hydraulic gradients show the groundwater flow direction is northwest to southeast excluding localized anomalies. Laboratory testing includes moisture content, grain size analysis, unit weight, liquid and plastic limit, and permeability characteristics. Geochemical testing was designed based on organic vapour measurements, visual and olfactory evaluations, and EM surveys. The chemical testing included phytotoxicological analyses, TEH, BTEX, TPH, PAH, VOC and PCB’s. Additional samples were analyzed for lakefill and decommissioning criteria plus other EPA parameters. An SWA groundwater analysis package was also performed.

The findings were compared to industrial landuse criteria and site remediation and monitoring recommendations were provided. A phased site cleanup program for elevated soil and groundwater concentrations with onsite environmental sampling and monitoring was undertaken.