Estimating the Hydraulic Conductivity of the Ajali Sandstone in the Udi Area of South Eastern Nigeria from Pumping Test and Grain Size Based Empirical Analysis

The Maastrichtian Ajali Sandstone in the Udi area of south eastern Nigeria has been assessed by means of pumping test and grain size based empirical analyses, to estimate the hydraulic conductivity of the aquiferous formation. Hydraulic conductivity (K) values from pumping test ranged from 10.41 to 17.85 m/day while estimations from grain size based empirical methods of the United States Bureau of Reclamation (USBR), Pavchich, Slichter and others gave (K) values that ranged from 5.24 to 39.95 m/ day. Statistical correlation analysis shows that a strong positive correlation (r=0.96) exist between K values from pumping test and those from grain size based empirical methods. Study reveals that grain size based Pavchich method (K=14.74 - 24.92 m/day) could adequately replace pumping test for the determination of the hydraulic conductivity of a homogeneous and isotropic aquiferous formation like Ajali Sandstone.