KUALA LUMPUR, Aug 27 — The highly toxic and flammable sewer gas accumulated in a 15-meter-high sewage tank at the Indah Water Konsortium (IWK) plant in Pantai Dalam posed a significant challenge for the search and rescue (SAR) teams working to locate the victim of the Jalan Masjid India sinkhole incident.

A source informed Bernama that the danger was identified after SAR team members were deployed to inspect the tank, initially with two personnel on Sunday and four yesterday.

"There are various hazardous gases in the tank, including hydrogen sulfide and methane, which are both highly toxic and flammable,” the source said.

Hydrogen sulfide is a colourless, highly toxic, and flammable gas with a distinct smell of rotten eggs. It is produced by biological activity when bacteria decompose organic matter in the absence of oxygen (anaerobic conditions).

Sources revealed that SAR personnel used specialised personal protective equipment (PPE), designed for single use, and breathing apparatus when entering the tank.

The source added that SAR personnel will be lowered into the tank and the filter section using a rope system to search for any clues regarding the victim.

"The search operation involves using hands and specialised tools. While inside the tank, SAR team members must avoid making abrupt movements or disturbing the pile of excrement excessively, as the accumulated methane gas is flammable. Everything must be handled with great care.

"Search efforts will continue in the tank and the filter area to identify any foreign objects trapped after the faeces were pumped out. As of yesterday, no positive results have been found,” the source explained.

In the incident on Friday (August 23) morning, the Indian tourist, identified as Vijayaletchumy, 48, went missing after falling into an eight-metre-deep hole. She was on her way to a nearby temple for breakfast when the ground suddenly caved in. — Bernama