The Palapye geotechnical mapping project was conducted at a regional 1: 50 000 from 2018 to 2019. The project focused on the investigation of soil strata at shallow depths where soil properties are of significance to normal infrastructure development and land-use planning decisions. The study determined that 7.2% of the study area was of favorable conditions, while 71% was classified as intermediate. Therefore, 78.2% of the study area is generally suitable for structural development with minimal or manageable constraints The remaining 21.8% was identified as the least favorable areas and these are located along flood plains and localized depressions (natural pans). These areas are characterised by clayey sands of medium to high expansive potential. This means in these conditions, compression under load due to volume change can be expected.
Geotechnical constraints are taken into account at the design and construction stages of the project. The geotechnical evaluation of suitability for development was carried out through a combination of historical data, field observations, and laboratory tests. A hydrological study is required for completeness and revision of the suitability map to incorporate flood data to delineate flood lines. Most constraints for normal residential development can be addressed by removing unsuitable in-situ material and importation of competent gravel fill of G5 or better whilst maintaining proper drainage control around structures. Possible foundation options depend on the type of structure proposed, subsurface material properties, and drainage conditions of the area.
It is recommended that a Structural Engineer be engaged to determine the best economical foundation option informed by a detailed site-specific geotechnical investigation. These recommendations are made to provide guidance for light residential structures focusing on the most economical options.
Keywords: geotechnical, suitability, mapping, constraints, development.
Click here to download Palapye Suitabilty map