A method is provided for simultaneously developing caverns while depositing wastes or other materials in them. A well is first drilled into a salt formation and the development of a salt cavern by means of solution mining is initiated. When the development of the cavern has been carried out to an extent sufficient to accommodate the injection of a prescribed amount of wastes or other materials, injection of the wastes or other materials through the well is started while continuing to develop the cavern by solution mining. The injection of the wastes or other materials may be carried out continuously or intermittently. The proportion and rates of wastes or other materials and mining water injected into the well are monitored and regulated so that cavern development continues at a rate that allows the cavern to reach an intended prescribed size while the wastes or other materials are injected and deposited into the cavern.