COEUR d'ALENE - A local engineering firm said removing hundreds of trees along Coeur d'Alene's dike road as ordered by the U.S. Army Corps of Engineers could cost around $1.6 million.

The estimate, compiled by Ruen-Yeager and Associates Inc., was presented last week to an ad hoc committee created to explore options to save the trees along Rosenberry Drive, also known as dike road.

The figure exceeds the roughly $50,000 to $100,000 the city of Coeur d'Alene had originally estimated it could spend after it learned of the federal order in March.

"This was more than expected, but until you go to bid on it, you never know what it's going to be," said John Bruning, committee chairman. "It's a big undertaking."

The engineering firm also provided a feasibility study for a modification to the dike system that could preserve the trees, according to committee members.

By installing 'sheet pilings' - a metal floodwall driven through the center of the dike system - a majority of the vegetation on the dike could be preserved.

This option could cost up to $3 million and would require permit approvals that could take some time to assemble, the Kootenai Environmental Alliance reported on its website. The group is represented on the committee.

But nothing is set in stone, and the 11-member committee is still exploring its options, Bruning said.

Bruning said the group is trying to schedule a meeting in the next month or two with Federal Emergency Management Agency officials to determine whether the 100-year flood plain area - the Fort Ground area that would be directly affected by a flood - can be certified by a third party for insurance purposes.

Without the Army Corps certification, future building in the area could become all but impossible there. The Corps ordered around 500 trees to be removed along the levee near the Spokane River and North Idaho College to receive the certification.

The city of Coeur d'Alene has two years to comply, but is looking at other options while it completes some of the smaller tasks associated with the order, such as earning permits for bathrooms and picnic tables along the dike encroachment.

The order is also being challenged in court by KEA. It was ordered after the federal department studied levee safety following Hurricane Katrina in 2005.

Ruen-Yeager and Associates representatives, who had been contracted by North Idaho College, couldn't be reached for comment Tuesday.