The soil resources in the Highvale Mine area are predominantly thin Black Solodized Solonetzic and Gleysolic soils developed on residual bedrock of the Edmonton Formation. A significant amount of Gray Luvisolic soils, developed on residual sandstone bedrock of the Paskapoo Formation, are al so present. The Solonetzic and Gleysolic soils occur on the level to gently undulating terrain near the lake, while the Luvisolic soils are found on the complex topography with moderate to extreme slopes along the south side of the mine area.
Since the mine opened in 1971, the soil salvage and replacement requirements have evolved to more closely meet the land capability targets discussed above. From 1971 to 1979, TransAlta was required to salvage all topsoil and replace it on levelled minespoil in Pit 01. With growing concern about the potential for salt to move from the minespoil into the topsoil, TransAlta was also required to start replacing a layer of subsoil in 1979. From 1979 to 1981, a 0.3m layer of subsoil and all topsoil was salvaged and replaced on levelled minespoil. This occurred in parts of Pit 01 and Pit 02.
From 1982 to 1983, TransAlta salvaged and replaced 1.0m of subsoil as well as all the topsoil in parts of Pit 02. During this time, a more rigorous evaluation of soil suitability for use in reclamation was conducted at Highvale, using soil chemical criteria provided in Alberta Agri~ulture (1981). The result was that, over 80% of the mine area, subsoil was suitable and
salvaged for replacement in a 1.5m layer above levelled minespoil. In the remaining 20% of the mine area, only a thin layer of suitable subsoil was available and salvaged for replacement in a 0.5m layer above minespoil. Soil salvage and replacement continued in this manner from 1983 to 1986.