The Adequate Public Facilities Ordinance was created by the county in an effort to ensure schools, roads and other infrastructure are adequate to handle growth.
County Commissioner John C. Munson said after the meeting that approving the fee was a fair thing to do.
"Why should all taxpayers in the county be paying?" Munson said. "Developers should be required to pay. It takes the burden off the taxpayers. It's the fairest way I can think of."
According to a county document, 2,076 housing units are proposed for the Robinwood Drive area, along with several commercial properties, including a new Washington County Hospital.
About $12 million in road improvements is needed in the Robinwood, Edgewood and Mount Aetna corridors, Director of Public Works Gary Rohrer said.
The fee approved Tuesday would require developers to share the costs of the needed improvements, Rohrer said.
"Instead of reacting, we're trying to be proactive here," Rohrer said.
Rohrer asked the commissioners Tuesday to require the Washington County Health System to pay $2.17 million toward road improvements to accommodate the proposed hospital relocation to Robinwood Drive.
Developers in other parts of the county also are paying to improve roads.
Rohrer said developers building in the Long Meadow Road and Maugans Avenue areas are required to pay a $5,600 per dwelling unit fee for road improvements.
The commissioners are considering revising the APFO so that developers would pay about a $6,500 fee per dwelling unit if they build in areas where elementary schools are at 85 percent capacity.
A vote on the school APFO fee might be taken next month, Commissioner Doris J. Nipps has said.
Money from that fee would go toward building additional classrooms and other school improvements.