Campaigners are taking Cardiff Council to court over a proposed landfill site in countryside outside the city.
Farmer Toni Evans says they are fighting for every Cardiff resident
Two sites near Rhydlafar and Creigiau are being considered but there are fears it would blight villages nearby.
Opponents launched a judicial review of the decision by the authority to carry out the landfill investigations there.
They say the decision was based on a fundamentally flawed report. The council says it is looking a number of options for future waste disposal.
The legal challenge follows a public meeting in Pentyrch last month attended by 700 local residents.
Campaigners say the council's decision to investigate the sites north of Cardiff fails to take into account Welsh assembly guidance as well as planning policy and EC directives.
Local farmer Toni Evans, of Fight the Landfill, said: "We have asked Cardiff to reconsider this decision but they have refused.
"The proposals don't make sense and will mean that thousands of pounds of tax payers money could be wasted on investigating sites that could then be blocked by the Welsh assembly."
Mrs Evans said: "'I'm not fighting this just for myself and my family and the other families affected. I'm fighting this for every resident in Cardiff, in south Wales.
"In this day and age the council should be looking at technological advancements in waste management not building big rubbish mountains"
Lamby Way is Cardiff's current landfill - the destination of 90% of its waste - but will run out of space in a few years.
Lamby Way landfill site will be full in three years
The council hope new technology will mean they will not have to bury so much rubbish in the future but at the moment they are looking for a landfill site.
A fighting fund has been sent up to pay the campaign's legal costs - which could exceed £40,000 - and a website has also been set up.
The campaign has also won the support of Cardiff West MP Kevin Brennan, who said the council should be concentrating on improving the amount of recycling in the city.
"They shouldn't be looking for huge new expansion of landfill which is what this would represent if it ever were to come to fruition.
"And it would do serious and permanent damage to Cardiff's image."
Cardiff Council has already said a list of possible landfill sites had been compiled and would be considered over the next two years.
The authority is also investigating the "preferred" solution of a waste treatment facility to reduce the need for landfill sites, and would be encouraging people to recycle more.