Flyash disposal problems at thermal power stations—an experimental study

Abstract

Disposal of flyash at thermal power stations is carried out in the form of ash slurry by mixing the ash with water. The ash slurry is stored in an ash pond. The water in the slurry is gradually drained out, through decanting wells, earthern embankments and over spillways, leaving the ash to deposit in the pond. It is observed that, the design of decanting wells presently being used allows a considerable amount of flyash to flow out with water, leading to the contamination of soil and the water courses. Further, it is observed that, the failure of earthern bunds of ash ponds, which results in a major damage to the environment, is mainly due to ineffective functioning of filters in the bunds. This paper presents the details of an experimental investigation carried out to study the role of geotextiles in improving the performance of decanting wells and earthern bunds. Two series of experiments were carried out. In the first series two model decanting wells were tested with geotextile lining. In the second series, a number of model earthern bunds were tested with and without geotextiles. Economics of providing geotextiles in earthen bunds is studied. The results indicated that, the use of geotextiles is economical and effective in improving the performance of decanting wells and the earthen bunds of an ash pond. Copyright © 1999 John Wiley & Sons, Ltd.