Remediation of fractured rock aquifers contaminated by hexavalent chromium

The contamination characteristics of bedrock fissured aquifer, selection and implementation of remediation technologies, and evaluation of remediation effects are analyzed based on the remediation project of hexavalent chromium-contaminated groundwater in a machinery company in Shandong Province. The results show that the shape and the scale of hexavalent chromium-contaminated plume in bedrock fissured aquifer mainly depends on groundwater flow field, water abundance of aquifer and occurrence of fault zone. The buried depth of contamination plume depends on that of aquifer. The complex hydraulic connection condition of bedrock fissured water is an important factor causing great difference in spatial distribution of contamination concentration in the site. Through technical and economical analysis, a multi-technology combined remediation scheme including groundwater barrier, ex-situ treatment after pumping and in-situ chemical reduction technology is put forward. After field remediation, the concentration of hexavalent chromium in groundwater in all monitoring wells is lower than that of class IV standard(0.1 mg/L) in "Chinese Standard for Groundwater Quality", and the successful remediation percentage is almost 99%. This successful implementation project can provide reference for the design and construction of remediation of contaminated fissured rock aquifers.