Some Negative Effects of Wastewater on Clayey Soil

Abstract

This study deals with the effect of wastewater on some physical, chemical andconsolidation properties of clayey soil and investigates the effect of wastewater flowbeneath buildings’ and structures’ foundations due to; breaking of wastewater pipes,the permeation of sewage water in to the soil, or its flow on the land that hasn’t beenconstructed yet.Soil samples have been taken from the University of Technology site at a depth (1–1.5) m and the preparation of samples were in two manners: the first by takingundisturbed samples which have been flooded with wastewater that allowed topermeation and flow through soil sample, the second, by taking disturbed samplessaturated with wastewater to ferment.The soil that used in this study was silty clay with low plasticity (CL-ML) and theresult of this study which lasted for (10) months showed an increase in the chlorides and sulphates ions during the first months and then decreased, it has been noticed anincrease in the concentration of carbonates ions along the period of study and anincrease in organic matter due to wastewater nature.The results of soil- wastewater interaction showed an increase in liquid limit, plasticlimit and plasticity index for both undisturbed and disturbed samples and the specificgravity of soil decreased due to wastewater chemical contents. The void ratio has beenincreased and preconsolidation pressure decreased which may be attributed to thedissolution of soluble salts and the influence of carbonate bonding that may be brokenwhen subjected to load. Also, the results showed an increment in the ability of soil tobe compressed when soil compression index (Cc) increased and soil swelling index (Cr)increased, too.