Arsenic Contaminated Groundwater Treatment Pilot Study at the Sharpe Army Depot (SHAD) Lathrop, California. Task Order 9

Groundwater treatment for the removal of contaminants may be needed at a number of U.S. Army installations, including Army depots. Treatability of potentially applicable technologies may be needed to facilitate design and operation of treatment systems. The study described here is a treatability test for the removal of arsenic from groundwater. The goal of the study was to evaluate the effectiveness of ion exchange (IE), granular activated carbon (GAC) , and activated alumina (AA) for the removal of arsenic from groundwater. Laboratory IE, GAC, and AA isotherms were conducted to select the two best performing carbon and resin types and the operating pH for the carbon and alumina media for further testing. Pilot scale continuous flow column tests were conducted at Sharpe Army Depot in Lathrop, California, using the two carbons (Calgon Filtrasorb 400 and Hydrodarco 3000) and the two resins (Amberlite IRA 402 and Ionac A-641) selected during the isotherm studies. Alcoa F-1 AA was also used during the pilot scale continuous flow column tests. The carbon and AA were tested at an adjusted pH of 4.0 and the resin was tested at natural pH. A pilot scale, conventional packed column air stripper was used to remove volatile organics (primarily trichloroethene) from the ground water prior to treatment by the pilot scale columns. The data from the laboratory and pilot study were analyzed and a report was prepared to present the results and conclusions.