Geotechnical hazardous effects of municipal wastewater on plasticity and swelling potentiality of clayey soils in Upper Egypt

In Upper Egypt, the settled areas were constructed on the flood plain clayey soils which situated on both sides of River Nile course. These clayey sediments are consisting of silts, clays and sands with average values of 47.4, 40.3 and 12.3% respectively and classified as inorganic clays (CL). The clay mineral composition of these inorganic clayey soils constitutes of montmorillonite, kaolinite, illite–montmorillonite mixed layer and minor percents of chlorite and illite. These populated old cities were extended during last three decades in the same time the sewage networks are not found in new extended areas. So that, the private sector was forced to storage wastewater in so called wastewater-tanks below or near the houses. These tanks sometimes filled completely or broken then the wastewater which rich in organic matter will saturate the clayey soils. The wastewater had been caused an increasing in original plasticity and swelling potentiality of these clayey soils. So that, serious damages such as wall cracks and foundation tilting were observed.