Prior to discussing laboratory approaches and field-scale implementations in detail, we discuss Nong-Nea villagers’ risk and risk reduction strategies using vetiver systems to understand the logic of the three vetiver application strategies. Figure 3 illustrates a risk conceptual model from illegal dumping at Nong-Nea village. There are two types of source zones, accessible and inaccessible. The accessible source is Mr. Manus’s pond, while the inaccessible sources are two waste management facilities. These two are inaccessible because the owners do not allow any stakeholders, including researchers and government agencies, to assess or remediate their properties. Thus, we had no choice but to investigate the contaminant signal in shallow groundwater and soil outside their fences using a membrane interface probe (MIP), and we found a high potential of contaminant release from their properties (Figure S2). Contaminants may be released from accessible and inaccessible source zones via overtopping the dike, infiltration or percolation, and spills. Released contaminants can be transported via runoff, shallow groundwater flow, and surface water flow (through Tad-Noi creek). Nong-Nea villagers and aquatic and terrestrial animals may be exposed to contaminants via drinking water, dermal contact, or the food chain. Inhalation of contaminated dust is also possible, but it is not likely to be a substantial risk.