Site characterization and risk assessment in support of the design of groundwater remediation well near a hazardous landfill

Abstract

This study was undertaken to support a remediation technique that will be applied to contaminated groundwater in the vicinity of Ghonan landfill, eastern Saudi Arabia. Preliminary field investigations involved hydrogeological characterization of the entire area. The improved understanding of the underlying geology and groundwater movement gained from the preliminary studies helped in determining a test site within the proximity of the landfill. One remediation well and five monitoring wells were constructed at the test site. Optimum pumping rate for the remediation well was determined to range from 2.642 through 7.926 gallons per minute (gpm) (0.01 m3/min through 0.03 m3/min) based on site-specific hydrogeological investigations and mathematical simulation. A concentration of 0.05 mg/L of methyl tertiary-butyl ether (MTBE) contaminated the aquifer in the test site. The simulated concentration of MTBE at the point of exposure after a period of 2 years was found to be higher than the maximum contaminant level of 0.005 mg/L set by the United States Environmental Protection Agency (U.S. EPA). The results of risk assessment conducted revealed that domestic use of groundwater in the study area through any of the exposure pathways (ingestion, dermal contact, and inhalation in the shower) may lead to development of health risks to human receptors. The landfill, which is being operated as a hazardous landfill and a dump site, may become a source of groundwater pollution in its vicinity in the near future. As a potential health risk, it should be controlled properly by remediating the aquifer and implementing environmental measures to the landfill users.