Geotechnical Issues for Closure of Ammonia Soda Ash Waste Ponds

The paper describes the application of geotechnical site characterization, material testing, test fill construction and settlement analysis to the closure design for two settling ponds at a former chemical plant in southwestern Virginia, USA. The ponds contained by-product material from ammonia soda ash manufacturing that had been slurry-deposited to thickness up to 20m over a total area of approximately 480,000m 2 . The material is a man-made particulate exhibiting a unique structure with high moisture content, high compressibility, and unusual geotechnical properties. Closure construction was successfully completed in 2001. The paper demonstrates that although the by-product material exhibits unusual characteristics, the application of geotechnical engineering principles allowed the successful execution of pond closure.