A national historic preservation group is endorsing a controversial U.S. Army Corps of Engineers plan to bury the site where Kennewick Man was found under rocks and dirt.

The decision from the Advisory Council on Historic Preservation sets up another clash between the corps and the U.S. Senate over the site where the controversial bones were found in 1996.

Congress is considering blocking the corps protection plan, at the request of U.S. Sen. Slade Gorton, R-Wash., thus keeping the site open for scientific study.

The corps wants to bury the site where the bones were found to prevent any additional bones from being uncovered by waves from the Columbia River.

In documents filed in federal court Wednesday in Portland, lawyers for the corps said the agency “intends to implement the proposed site protection plan on … March 24, 1998, or as soon thereafter as they are able to obtain” approval from all agencies necessary.

Corps spokesman Dutch Meier said a contract still has not been awarded for the work, which includes flying materials by helicopter to the river shore site in Columbia Park.

Kennewick Man - a skeleton later dated at 9,200 years old - was found partially buried there in July 1996.