Geotechnical Assessment of Soil Permeability in Land Development Areas

Abstract

Infiltration is identified as one of the best operational and sustainable methods to handle urban storm water. Until recently, in stormwater management designs and selection of best stormwater management strategies, permeability value of different soils were not been considered as major factor. Due to the increasing housing density local land development authorities requires storm water runoff from developing lots to be retained/detained within the property. Due to lack of information on local soil properties, specifically permeability rates within the soil predominant in land development areas, it is difficult to assess storm water retention/detention requirement. This case study was carried out within the new development areas in Gosnells in Western Australia mainly focusing on identification of different soil types with respect to their infiltration capacities in selection of best stormwater management strategies. The Guelph Permeameter have been used to investigate the saturated permeability of different soil types. Based on the above tests, the results have been categorized in to four main types of permeability groups; Very Rapid (> 1.56 m/day), Rapid (0.48<1.56 m/day), Moderate (0.12<0.48 m/day) and Slow (<0.12 m/day). Finally, with the help of the existing soil map, the point represent permeability data were been generalized logically. These results have been used to develop permeability maps representing the areal average. The soil types and their observed permeability values compared with the literature; soil classification data of Department Agriculture. The comparison shows that field test data has a higher agreement with literature based soil classification. These field tests will be extended to identify the best stormwater management practices for the selected land development areas. The result will be useful for land developers as well as authorities, decision makers and policy makers to come up with sustainable land development strategies.