Urban geology of the National capital area |
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Urban Geology of the National Capital Area Sources of information
Engineering borehole logs: The database contains 2370 engineering borehole logs compiled from government agencies and private engineering firms. The source of information is not revealed for reasons of confidentiality. In many cases, geotechnical properties such as penetration resistance, shear strength, water content, and Atterberg limits were also compiled, but these are not reported in the borehole logs due to variations in methodologies and in many cases to preserve the confidentiality of the reports. These properties were although used in regional syntheses. Although the stratigraphic information provided in these logs is highly reliable, it should be used only in a regional context and is not meant to replace site-specific investigations. Unfortunately the distribution of engineering boreholes is limited to areas of major constructions, such as, industrial sites, the core of urban centres, and along major transportation corridors.
Water well records: The database contains 23192 water well logs that were obtained from the Ministère de l'Environnement du Québec and the Ministry of Environment of Ontario. Due to proprietary reasons, only the stratigraphic logs are provided in this database, information on water quality and yield, or any other information contained in the original databases, should be directed to the provincial ministries. The provincial databases are compiled from reports generated by water well drillers, who have to file a report for every well drilled in respective provinces. Since the primary purpose of these drill holes is for water supply and the well drillers are generally not geoscientists, the terminology and precision of stratigraphic logs vary considerably between well drillers. Even though well records are generally not as accurate as engineering borehole logs, they do provide an excellent source of information in rural areas, as indicated on the database location map.
Shallow Seismic Surveys: The database contains 1610 seismic profiles produced by the Geological Survey of Canada in 1970. The surveys were produced to provide depth to bedrock in areas where no other information was available. The recorded seismic velocities provide information on the unconsolidated sediments but these are of limited reliability due to the technique used at the time. The seismic surveys were conducted along roads in rural areas, as shown on the database location map.
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