Groundwater

The groundwater beneath the Weldon Spring Site has been the subject of studies for many years. Contaminants of concern include tricloroethene (TCE), nitrate, nitroaromatic compounds and uranium. Field studies have been conducted to evaluate various methods of extracting contaminated groundwater or treating the contaminants in the ground beneath the site. One such test was a pump and treat field test to determine whether the injection of clean water to flush the aquifer (artificial recharge) or use of an angled extraction well to intersect vertical fractures could significantly improve contaminant removal rates.

A pilot scale treatment using a method called insitu chemical oxidation (ICO) was implemented to treat trichloroethene (TCE) in the groundwater south of the former raffinate pits. From January to June of 2002, pilot scale injections were performed. Approximately 15,000 gallons of 0.1% sodium permanganate solution were introduced into the aquifer followed by a second injection of 25,000 gallons. Objectives of this pilot study included determining the radius of influence of the injections along with the ability to destroy TCE without adversely affecting the aquifer. A final agreement (Record of Decision) with the EPA and the State of Missouri is still being discussed for the groundwater operable unit at the Chemical Plant.