CALAIS, Maine&nbsp- There was a lot more ledge than builders anticipated, but that has not delayed construction of a $48 million U.S. Customs house on one of the nation’ s busiest border crossings with Canada.

The catch: It’ s going to cost taxpayers an extra $10 million.

“Our staff has really done a great job of keeping the project going even with the problems we had with the ledge [underground rock],” said Dennis Smith, regional administrator for the U.S. General Services Administration during a tour Tuesday.

But, he said, more blasting and fill were needed and “with all of that the cost is going to be higher for the project.”

Excavations from the site had been expected to be used for fill, but have been found to be unsuitable. So they continue to be disposed of off-site, the GSA said in its quarterly report.

As of June 30, the project was 18 percent complete.

Smith was joined on the tour by representatives of Maine’ s congressional delegation and state and local officials.

So far, the commercial processing building is just steel girders connected together.

Officials paused during Tuesday’ s tour to watch a 140-foot span beam, loaded on a huge flatbed truck, inch slowly across the site toward the new bridge where it will be lowered into place.

In addition to the new customs facility, Maine and New Brunswick are sharing the cost of the $8 million bridge that will connect Calais with neighboring St. Stephen, New Brunswick. The bridge spanning the St. Croix River will be entirely U.S.-made.

Although Canada will be ready to open its part of the bridge and customs house this year, it will have to wait because the U.S. side of the bridge won’ t be ready until November 2009. When the project started two years ago, it was hoped both customs facilities would be ready by the end of this year, but the GSA plan ran into problems that delayed construction.

As a compromise, local officials pushed to have a portion of the bridge open for commercial traffic by year’ s end, but Smith said it would be too costly.

“That does not make any sense. It would have ended up costing far more money,” he said.

Right now two bridges — the downtown Ferry Point Bridge and the Milltown Bridge, near the city’ s industrial park — connect the two communities. Both bridges have customs facilities.

The new site is on a 54-acre parcel that abuts the river and is close to the Moosehorn National Wildlife Refuge.

Once completed, the complex will comprise 100,000 square feet of buildings — one for commercial traffic and one for vehicles — along with canopies and parking.

Construction of the customs house was done with an eye to the aesthetics.

GSA project manager Frederick Amey said Tuesday that drivers entering the port will be able to see Magurrewock Mountain in the distance.

“The designers endeavored to leave a visual opening between the two buildings as a connection to the two countries [on either side of] the river,” he said.

After the tour of the construction site, officials traveled to the Milltown bridge, where GSA is spending money upgrading the customs booth, along with other changes.

From there it was off to the Ferry Point Bridge, where officials toured what soon will be the new cargo-processing center.