The Franklin County Commission Tuesday approved a supplemental agreement for construction engineering work on a new bridge on Enoch’s Knob Road.
The county will pay CDG Engineering an additional $14,800 for additional testing and daily site visits.
Highway Administrator Eva Gadcke said the additional costs are because of changes to federal requirements.
The bridge is a federal Surface Transportation Program project, which means the county will be reimbursed for 80 percent of the cost by the federal government.
The federal funds were approved by the East-West Gateway Council of Governments board as part of the 2009-2012 Transportation Improvement Program.
The board, made up of elected officials from Franklin, St. Louis, Jefferson and St. Charles counties in Missouri, the city of St. Louis and several Illinois counties, administrates federal transportation funds for the region.
To secure the federal funds, the county has to meet federal regulations, Gadcke said.
Those regulations have changed since the county entered into its original contract for construction engineering with CDG three years ago, she said.
The firm originally was contracted for $46,600. The new contract is for no more than $61,400.
The county has already signed a contract for construction of the bridge.
That contract for $1,397,254.60 went to L. Krupp Construction, Ellisville.
The bridge, which crosses Boeuf Creek, will be a three-span, steel plate girder bridge.
The old bridge, a steel truss with a wooden deck, was built over 100 years ago by the Missouri Bridge & Iron Company.