New Castle County Executive Matt Meyer signed an ordinance at a press event that limits the height of landfills to 140 feet.
The county and others were unsuccessful in efforts to convince the General Assembly to impose the height limit.
The construction materials landfill is in the Minquadale neighborhood of New Castle, near the New Castle County Police complex.
The height extension proposed by national landfill and refuse operator Waste Management would provide millions of dollars spread over a period of years to a neighborhood association for Minquadale that favored the proposal.
Waste Management claimed opponents of the landfill, which may close in coming years if its height is not raised were issuing misinformation about the project.
Foes had claimed among other things that much of the waste used at the landfill was coming from out of state.
The county ordinance could be subject to a legal challenge from Waste Management.
The Delaware Department of Natural Resources and Environmental Control has jurisdiction over landfills.