Naturally Occurring Radioactive Materials (NORM) wastes are generated in huge quantities in several industries and their management has been carried out under considerations of industrial non-radioactive wastes, before the concern on the radioactivity content was included in the legislation. Therefore these wastes were conditioned using conventional methods and the waste disposals were designed to isolate toxic elements from the environment for long periods of time. Spanish regulation for these conventional toxic waste disposals includes conditions that assure adequate isolation to minimize the impact of the wastes to the environment in present and future conditions. After 1996 the radiological impact of the management of NORM wastes is considered and all the aspects related with natural radiations and the radiological control regarding the management of residues from NORM industries were developed in the new regulation. One option to be assessed is the disposal of NORM wastes in hazardous and non-hazardous waste disposals, as was done before this new regulation. This work analyses the management of NORM wastes in these landfills to derive the masses that can be disposed without considerable radiological impact. Generic dose assessments were carried out under highly conservative hypothesis and a discussion on the uncertainty and variability sources was included to provide consistency to the calculations. (C) 2016 Elsevier B.V. All rights reserved.