Statistical evaluation of the effect of secondary municipal wastewater and solid waste leachate on ground water quality at Lawspet in Puducherry, India

At Lawspet area in Puducherry, India, a unique situation of co-disposal of solid waste dumping and secondary wastewater disposal on land, prevails simultaneously within the same campus. So an attempt is made to assess the combined effect of this co-disposal on the environmental quality and pollution effects on groundwater quality with a view to correctly monitor the situation. Multivariate statistical analysis like hierarchical cluster analysis (HCA) and discriminant analysis (DA) were employed. HCA was performed on borewells, physiochemical parameters and seasons. Borewell clustering identified four clusters illustrating varying degree of groundwater contamination. In parameter clustering, two major clusters were formed indicating hardness and anthropogenic components. Temporal clustering identified three major clusters indicating pre-monsoon, monsoon and post-monsoon. Discriminant analysis revealed nine significant parameters which discriminate four clusters qualitatively affording 86% correct assignation to discriminate among the clusters. Also three major components viz. anthropogenic, hardness and geogenic responsible for groundwater quality in the study area were identified. Conclusively the investigation revealed that the direction of the contaminant transport is towards the southeast direction of the study area, where all the borewells (100%) are affected.