As part of settlement, Honolulu will pay $875,000 in penalty as well as built a $16m worth solar power system.
The settlement is the result of the city’s failure to deploy a gas collection and control system by 2002 at Kapaa Landfill.
The control system, however, was installed in 2013.
US Justice Department Environment and Natural Resources Division assistant attorney general John Cruden said: "This settlement holds Honolulu accountable for past failures to collect and control toxic gases and greenhouse gas emissions from the Kapaa Landfill, but it also lays the foundation for better environmental stewardship in the future.
"Residents who call Oahu home will realize the benefits of this agreement – which includes clean solar power production and reduced reliance on fossil fuels – for many years to come."
The 3.1MW solar project will feature photovoltaic arrays which will be installed on more than 250,000ft2 of buildings and open space area at the city’s program of waste energy recovery (H-Power) facility located in Campbell Industrial Park, by 2020.
The project will generate more than 5 million kilowatt-hours of electricity a year, sufficient to power 800 households.
