This book describes the geophysical investigation of a Sewage lagoon system at a sewage treatment site located at Ahmadu Bello University Zaria Nigeria using 2D seismic refraction tomography. Developed from a recent Master thesis in Applied Geophysics, the book describes the technique and methodology of data acquisition, processing and interpretation of 2D seismic survey involving refraction tomography. The book also describes the enhancement of tomographic sections interpretation through the integrated knowledge of the background geology with ray tracing and iterative modelling.