It has been worrying that so many toilets are being constructed without proper disposal plan in case of need. The twin pit system , if built scientifically, does not need disposal. But in the get hurry to report ODF villages, I doubt if they are being built with care. So then if a flood innundates the area, can you imagine the state?
Here's a study
http://wateraidindia.in/wp-content/uploads/2017/10/SBMG-toilet-technology-report_online.pdf