80 per cent and 40 per cent construction work completed at Okhla and Sonia Vihar STP April 17, 2023 | Key Segments, Municipal Wastewater, News & Developments, Ongoing, Project Updates, Wastewater Around 80 per cent and 40 per cent of the construction work has been completed at the Okhla sewage treatment plant (STP) and Sonia Vihar STP, respectively. This content is restricted.