Electrical resistivity tomography as a tool for community citizen science: A case study of community-driven investigation outside of the fence line

Abstract

Community citizen science approach is defined by US.EPA as “collaboratively led scientific investigation and exploration to address community defined questions, allowing for engagement in the entirety of the scientific process”. Citizen science and community citizen science have been effectively used in several environmental and public health protection projects. Moreover, US.EPA elaborates that community citizen science may include partnerships with professional scientists but orients toward community goals and working together in scalable networks to encourage collaborative learning and civic engagement. In Thailand, community citizen science starts to play substantial role in environmental forensics and environmental protection over the last five years, especially on cases of illegal dumping of industrial waste and leakage from landfill of industrial waste. Several improperly designed and operated landfill for industrial waste in Thailand appears to cause toxic substance contamination in groundwater and soil jeopardizing environmental and public health. Villagers nearby are very concerned but the major obstacle is the fact that villagers do not have authority to investigate the potential leakage sources in the fence line of a factory. Legally, Department of Industrial Work (DIW), Ministry of Industry has authority to investigate inside the factory's fence line but typically does not allow villagers or academia to investigate the potential contamination. Thus, DIW is frequently complained by affected villagers again helping factories to conceal the contamination. However, if the leakage from a landfill causes contamination outside of the fence line, villagers can request the DIW to order the factory to cooperate in source investigation inside the factory even with public participation. Thus, the key is to identify the leakage of landfill leachate out of the fence line. Electrical resistivity tomography (ERT) is an excellent technique to screen locations of leachate leakage along the fence lines. ERT can quickly and cost effectively detect electrical resistivity anomalies, a sign of landfill leachate with high ionic species. In this case study in Thailand, we worked with affected villagers to perform ERT long fence lines of an industrial waste landfill which did not allow anyone to take groundwater or soil sample or to perform ERT inside its fence line. However, from nine ERT survey lines, we found clear electrical resistivity anomalies along the fence line on the East in comparison to the control lines. Then, our research team together with affected villagers presented the ERT results to DIW agents and asked them to enforce the law to take groundwater samples in monitoring wells inside the factory. Then, we requested the DIW officers to disclose the results to public. Consequently, we found that the shallow groundwater sample in a monitoring well close the electrical resistivity anomalies is severely contaminated with landfill leachate. It has very high BOD (>70 times of the control), high COD (>70 times of the control), very high electrical conductivity (>105 times of the control), and high arsenic concentration (>290 times of the control). This confirmed the contamination caused by the factory, and the DIW officer had no choice but enforced the factory to do remediation. This is possible by using ERT with community citizen science.