The Liberal Democrats are demanding an explanation for the decision, after the Environment Agency (EA) granted Viridor permission to increase the amount of waste treated at the Energy Recovery Facility (ERF).
The ERF was only initially approved to handle household recycling. This expansion would see it take on commercial waste disposal.
The Lib Dems are calling for the Conservative government to intervene, and are writing to the Secretary of State for Environment, Food and Rural Affairs to review the decision.
Cllr Barry Lewis, the Lib Dem lead on the Environment for Sutton Council, said:
“This is the wrong decision. We have opposed the application to treat more waste at the ERF
from the start.
“I will be writing to the Secretary of State for Environment, Food and Rural Affairs asking why this unnecessary increase has been approved
“We will be closely scrutinising the EA’s reasoning for allowing this to go ahead. This includes reviewing if they have taken concerns raised by us and residents into account”.