Report on the breach in embankment of ash disposal site Island 4 of Sasan Power Limited, Singrauli, Madhya Pradesh
Joint Committee report by Madhya Pradesh Pollution Control Board (MPPCB) in Original Application No. 31/2020 Hirall Bisen Vs Reliance Sasan Power & Others on the breach in embankment of ash disposal site Island 4 of Sasan Power Limited (SPL) in village Siddhikhurd, post Tiyara, tehsil Waidhan, district Singrauli.
SPL had constructed two ash ponds for the disposal of ash generated from the coal burning, which was collected in two forms: bottom ash and fly ash. SPL also intermittently disposed ash in two low lying sites called Island 3 and Island 4. A breach in the embankment of Island 4 happened April 10, 2020. This happened when a poclain was working for routine strengthening of the top of the embankment and slipped on the downstream slope. Its excavating bucket removed a part of the slope while making an attempt to hold itself on the slope.
During the inspection by the Joint Committee, a stream was observed at the site of the breach - which was not present when the ash dumping started at Island 4. An important change that occurred on the upstream of the disposal site of Island 4 was the construction of a check dam on a stream around May 2019.
The check dam was nearly just a couple of hundred meters away from the site of the breach and was very near to the plant boundary and periphery of Island 4. In the altered situation, the water table in the area must have risen and since Island 4 was very close to the check dam , the groundwater under it must have also risen. With rising water table, there was build up of hydrostatic pressure on the embankment. Even though it was triggered by the excavating bucket of the poclain - the report said that with altered hydro-dynamics, the embankment would have failed eventually.
Note: The report of July 14, 2020 was uploaded to the NGT site on October 6, 2020