Monsanto Corp. (Augusta Plant)

• Site Profile
• Administrative Record Index (PDF): OU1 (19 pp., 830K), Deletion (25 pp., 1.0M)
• Additional Site Documents including Five Year Reviews, Records of Decisions (ROD) and Explanation of Significant Differences (ESD).
• For documents not available on the website, please contact the Region 4 Freedom of Information Office (http://www.epa.gov/region4/foiapgs/submit.htm).

Site Background:
The Monsanto Site located in Richmond County, Georgia, is a 75-acre site which began operation in 1962 and is still active today.  The plant manufactures phosphoric acid.  This process results in the generation of several waste products including arsenic trisulfide.  During the years of operation, Monsanto used two small onsite landfills (measuring 0.1 acre in size) to dispose of solid waste and sludges containing arsenic trisulfide.  Plant officials estimate that approximately 1500 pounds of arsenic was placed in these two landfills.  The site was first identified by the Georgia Environmental Protection Division (GEPD) in 1975.  In June 1979, at the request of GEPD, Monsanto began monitoring the groundwater in the vicinity of the landfills.  In 1980, the monitoring program revealed arsenic levels in the surficial aquifer exceeding the Maximum Contaminant Level (MCL).  In November 1983, Monsanto, under the supervision of GEPD, excavated the contents of the two on-site landfills and transported the waste to a RCRA permitted landfill in Emelle, Alabama.  In September 1984, the Monsanto Site was listed on the National Priorities List due to the potential groundwater threat.

Cleanup Progress:  Construction Completed
In January 1989, EPA issued a special notice letter to Monsanto to give Monsanto the opportunity to conduct, with EPA oversight, the Remedial Investigation (RI) and Feasibility Study (FS).  Monsanto entered into an Administrative Order on Consent in 1989.  The RI/FS indicated two small groundwater plumes of arsenic contamination on-site.  A Record of Decision (ROD) was signed in 1991 requiring Monsanto to monitor the groundwater on-site and install extraction wells in the areas where arsenic levels exceed the MCL.  The groundwater was extracted from the surficial aquifer and discharged for treatment at a Publicly Owned Treatment Works (POTW).  This process is to continue until all on-site monitoring wells indicate that the MCL for arsenic is not exceeded for a period of two years.  Since the site is adequately being addressed simultaneously by the State of Georgia under the Resource Conservation and Recovery Act (RCRA), and the same groundwater cleanup levels must be met to comply with the RCRA standards, the decision was made to defer the site to RCRA.  In late 1990, this site was deferred to RCRA.  The State is overseeing the pumping / discharge to POTW activities, and the quarterly groundwater monitoring at the site.  The company will continue pumping the groundwater until the MCL level for arsenic is reached.  This site was delisted from the National Priorities List (NPL) on March 9, 1998.  Five year reviews were conducted in 2000 and in 2005.  The most recent groundwater monitoring events indicate that only two on-site monitoring wells still exceed the MCL for arsenic, and the concentrations in these two wells have decreased significantly over time.