Supplying clean water for municipal, industrial and agriculture use across the globe is central to protection of public health and the environment. A key part of clean water is monitoring contaminants in water, soils, and sediments. Site characterization and monitoring are required to delineate the distribution of contamination, establish a site conceptual model for transport and fate, and assure that the predictions of contaminant behavior are reasonably correct. Advances in measurement technologies and modeling approaches including Internet-of-Things (IoT), big data, artificial intelligence, edge computing, numerical modeling, etc., are needed to fulfill the characterization and monitoring goals at contaminated sites. This session provides an overview of recent advances and novel approaches for characterizing and monitoring subsurface environments and invites submissions on laboratory, field, and modeling studies leading to more effective decision-making and management at contaminated sites.