Permeable Reactive Barriers (PRBs) have been used world-wide to remediate chlorinated solvents, metals and radionuclides from contaminated groundwater by precipitation, sorption, ion exchange and biodegradation in the last two ;ades. There is still however limited information regarding the formation of byproducts and subsequent pore clogging with respect to attaining the predicted, significant life spans (>50 years), even on the most popular PRE materials such as ZVI. This project aimed to visually examine and quantify morphological :hanges on ZVI barriers and subsequently to quantify the PRE longevity due to the occlusions.