Radiological characterization in DD & ER projects, when properly applied, can provide much needed information to better plan the project, to guide the progress of the remediation, to know when to stop remediating, and to prove officially that they job is complete. One of the more expensive radiological characterization tasks is the location and quantification of hidden or buried sources. Many samples must normally be taken for laboratory analysis, which is costly and takes much time. With InSitu gamma spectroscopy systems, this can often be done in the field. With Ge detectors and mathematical calibrations, identification and quantification of the contaminants can be done in a minutes. This capability can be further enhanced by taking multiple measurements, or using multiple energy regions from the same nuclide to determine the location of the radioactivity. Examples where this can be useful include measurement of floors, walls, and ceilings; determining the position and activity and identity of sources within a sealed container; and determining the activity vs. depth profile of neutron activation in concrete or radionuclides deposited on the ground or on concrete.