The Camorra were once again at the forefront of the illegal building and development industry. The authorities soon realised what was happening, and the saw the risk to existing cultural heritage, and stamped down upon the illegal constructions, which the Camorra simply moved their developments from previously occupied land into either the red zones (areas where the government had banned development due to the dangers posed by an eruption) on the slopes of Vesuvius, or they developed housing on land which they had used previously for illegal waste dumping, often making the ground unstable, and unusable for development in connection with local mayors and bureaucrats used to take money to close all two eyes. Undercutting the tenders of other contractors, the Camorra would first excavate and sell the volcanic pozzuolana, used in the construction industry, and then refill the cavities with tons of refuse and toxic waste, often imported from northern Italy, before recovering the waste and selling the land illegally for housing construction and residential development. It has been estimated that this industry was worth upwards of 11 billion euro a year to the Camorra. Anyway, it is impossible to trace a clear line of demarcation between local government and criminal associations for the simple reason that sometimes they work together for the same strike.