Reclamation of Sedimented and Consolidated Fly Ash Deposits

Increasing demand for electricity in the past few years increased the production of fly ash as by-product in Thermal Power Plants. This by-product is disposed off in wet form into lagoons, ash ponds or dykes, where ash particles settle by sedimentation process, resulting in very soft deposits. Reclamation of these abandoned ash ponds is essential for countries such as India, where land to population ratio is quite small when compared to other countries. For development of ash ponds into suitable sites, it becomes necessary to study the compressibility and stress versus settlement characteristics of abandoned ash deposits before any construction. This paper presents compressibility tests conducted on sedimented samples and load tests on untreated and granular pile/stone-column reinforced ash deposits. Results show a pseudo-overconsolidation behavior in the sediments. Load tests conducted on reinforced ash deposits yielded bearing capacities 1.8 to 2.6 times to those of untreated ash deposits indicating potential utilization of the ash deposits for supporting civil infrastructure construction.