Residents' views on plans for a controversial incinerator plant in Merthyr Tydfil are being heard by environment officials.
Covanta Energy say the £400m Brig y Cwm energy-from-waste plant will generate enough energy for all the homes in Merthyr and Caerphilly.
Friends of the Earth claims it would undermine efforts to cut waste and boost recycling.
The Environment Agency consultation will close on 10 June.
The plant, which aims to employ 81 people permanently, would take approximately 750,000 tonnes of non-recyclable household and business waste - mostly by rail - each year.
It would be west of Fochriw and next to the Ffos-y-Fran opencast mine site and generate about 70MW of electricity, enough to power up to 180,000 homes.
But in January Friends of the Earth's planning campaigner Mike Birkin said it was "terrible news".
"This huge waste plant will need to burn thousands of tonnes of valuable resources every year to make it cost-effective, and this will completely undermine efforts to cut waste and boost recycling," he said.
The Environment Agency's role is to examine environmental permit applications and decide whether to grant or refuse the application.
It will carry out an in-depth investigation to see if there would be any "risk or harm" from the site to the health of local people and the environment.
Agencies such as Public Health Wales, the local health board, and local authorities will also provide information.
Drop-in sessions will also be held next month for local people.
The Infrastructure Planning Commission is to decide on the overall plan for the energy-from-waste station and the process is expected to take several more months.