Predicting hydraulic conductivity around septic tank systems using soil physico-chemical properties and determination of principal soil factors by multivariate analysis

The knowledge of soil hydraulic conductivity is essential for the study of waste water infiltration rate into the soil subsurface. This study assesses selected soil hydraulic properties of soil around septic tank systems. Twelve soil samples were collected from four different locations within Ido Local Government Area, Oyo State, Nigeria. The analyzed parameters were done based on standard procedures. The measured values of soil physico-chemical properties were used to predict Ksat using multiple linear regression analysis. The soil water content, porosity, Organic Carbon, Soil pH, bulk density, soil resistivity and saturated hydraulic conductivity (Ksat) ranged from 20.6 to 26.2%, 34.3 to 47.2%, 0.11 to 0.37%, 5.8 to 6.2, 1.40 to 1.74 g/cm3, 4.55 to 5.80 O cm and 1.34 to 10.52 mm/hr respectively. The relationship obtained from regression analysis on data (R2 = 86.8) is a new model with empirical linear equation Ksat=82.08-5.93BD-10.98RES-2.69wc-16.12O.C+9.38pH which allows a new relation to estimate Ksat from the selected parameters. Principal component analysis (PCA) identified 3 major factors accounting for 92.7% of the total variation in the soil hydraulic variables. The result of Cluster Analysis (CA) shows groups based on correlation between hydraulic parameters and topographic settings.