A method of treating a solid matrix containing organic contaminants is provided. The method comprises the steps of a) injecting ozone into the solid matrix for a period of time known as the pulse duration; b) interrupting the injection of ozone into the solid matrix for a period of time known as the gap duration; and c) repeating step a) at least one additional time. Gap durations of from about 2 hours to about 48 hours are disclosed. Pulse durations of from about 0.25 hours to about 8 hours are also disclosed. Recalcitrant organic contaminants are treated.