DES MOINES, Iowa (AP) – Iowa officials will allow work on a four-state oil pipeline to go forward after the company submitted a plan to avoid disrupting an American Indian burial ground.

Department of Natural Resources spokesman Kevin Baskins said that Texas-based Dakota Access LLC was given an amendment on its permit to dig at Big Sioux River Wildlife Management Area.

Instead of a trench, the pipeline will be built about 85 feet underground using special boring equipment, Baskins said.

State Archaeologist John Doershuk said the company’s plan is satisfactory, but Indigenous Environmental Network organizer Dallas Goldtooth says his group opposes the decision to allow construction to go forward.

The $3.8 billion, 1,150-mile pipeline spans four states. The Iowa section still needs permits from the U.S. Army Corps of Engineers.