The bridge would have cost about $7.75 million if plans to approach the landfill from Md. 63 hadn't been altered.
A revision to the agreement allowed the county to approach from U.S. 40, which would cut the cost of the bridge and access road.
The Md. 63 option would have required a 75-foot cut through hard shale and benched terraces for drainage. In addition, a bridge built to that alignment would have been about 20 feet higher and much steeper.
Washington County Commissioner James R. Wade has said the bridge project was a mistake because upgrading Independence Road could have been cheaper.
Washington County's Lund landfill is expected to cost more than $10 million to open, according to county figures provided Monday.
Startup costs include $4.34 million for the bridge and access road, $4.5 million for construction of the first 17.5-acre cell and $1.5 million for other site development.
The 425-acre site cost the county $1.2 million in 1990. About 165 acres are planned for use as landfill - which could last the county about 70 years, more than twice the original estimate.
The remaining acreage will be used for buffers, including a tree-covered berm to separate the landfill from homes on Independence Road.
The site planned for landfill use is at least 40 feet above the flood plain.
The landfill could open in three years, providing state approvals come through in a timely fashion and trash intake remains stable, county officials said. The county is seeking state approvals for the final trash disposal areas at the Resh landfill.
County Public Works Director Gary Rohrer said future landfill areas would cost roughly $350,000 an acre.
High construction costs are related to the demands of state regulations, which require two thick plastic liners, a number of other layers of materials to prevent leakage, and a leachate collection system.
"There are literally backup systems to backup systems," Rohrer said.