Direct 3D imaging of a pipe, buried at a depth of 1.5 m, using portable dense receiver array shows that small objects associated with large impedance contrast can be precisely imaged. Detailed velocity analysis applied to backscattered wavefield from small buried objects provides resolution of less than 10 m/s. Comparison of backscattered wavefield observations to analytical solutions show a generally good match. Theoretical calculations also show that the object can be detected with wavelengths much larger than its size due to the large contrast associated with its hollow shape. Dense spatial sampling is needed to capture the energy emitted from the scattering object and successfully focus it by diffraction imaging. Portable dense receiver array can provide a cost-effective solution for such tasks.