REMEDIATION OF GROUNDWATER CONTAMINATED WITH ORGANICS AND RADIONUCLIDES – AN INNOVATIVE APPROACH EASES TRADITIONAL HURDLES

摘要

Traditional approaches to the remediation of contaminated groundwater, such as pump-and-treat, have been used for many years for the treatment of groundwater contaminated with various organics. However the treatment of groundwater contaminated with organics and radionuclides has been considerably more challenging. Pump-and-treat technologies are generally not well suited for the treatment of groundwater contaminated with both organics and radionuclides for the following reasons: ? Technologies such as air stripping may remove organics, but are not effective at removing radionuclides ? Radiological contamination may be transferred to above ground piping, pumps, and equipment. Survey and release of the internals of this equipment is extremely difficult. ? Many local health departments strictly prohibit the re-injection of groundwater with detectable radiological contamination ? Treatment for radionuclides, such as ion exchange, can produce significant volumes of waste that can be difficult and/or expensive to disposition Safety and Ecology Corporation (SEC) was recently faced with these challenges while designing a remediation system for the remediation of TCE-contaminated groundwater and soil at the RMI Extrusion Plant in Ashtabula, OH. Under contract with RMI Environmental Services (RMIES), SEC teamed with Regenesis, Inc. to design, implement, and execute a bioremediation system to remove TCE and associated organics from groundwater and soil that was also contaminated with uranium and technetium. The SEC-Regenesis system involved the injection of Hydrogen Release Compound (HRC), a natural attenuation accelerant that has been patented, designed, and produced by Regenesis, to stimulate the reductive dechlorination and remediation of chlorinated organics in subsurface environments. The compound was injected using direct-push Geoprobe rods over a specially designed grid system through the zone of contaminated groundwater. The innovative approach eliminated the need to extract contaminated groundwater and bypassed the restrictive limitations listed above. The system has been in operation for roughly six months and has begun to show considerable success at dechlorinating and remediating the TCE plume and in reducing the radionuclides into insoluble precipitants. The paper will provide an overview of the design, installation, and initial operation phase of the project, focusing on how traditional design challenges of remediating radiologically contaminated groundwater were overcome. The following topics will be specifically covered: