ROCKWELL CITY, Iowa (AP) – Some Iowa landowners are raising concerns about construction of the Dakota Access oil pipeline, saying crews have left behind debris, released cattle from grazing areas and disrespected their land.

The Des Moines Register reports  that the complaints have been filed with local or state officials, including from several landowners who oppose the overall project and took part in demonstrations against it. Supporters of the $3.8 billion, four-state pipeline say the complaints don't represent major problems with the project.

The Iowa Utilities Board had received 22 official complaints as of late October, including 10 involving landowners. The board is in various phases of investigating the grievances, said board spokesman Don Tormey. But three complaints filed in the spring have been fully investigated and dismissed.

The pipeline is designed to carry oil from North Dakota through South Dakota and Iowa to a shipping point in Illinois. The project has attracted protests and strong opposition from the Standing Rock Sioux Tribe and its supporters, who argue that the pipeline – slated to skirt the tribe's reservation near the North Dakota-South Dakota border – threatens drinking water and cultural sites.

The company building the pipeline, Texas-based Energy Transfer Partners, insists that the pipeline is safe.

Spokeswoman Vicki Granado said the company takes its construction commitments seriously. She noted that none of the complaints filed with the Iowa Utilities Board has been validated so far.

"It is our goal to maintain this record throughout the rest of construction,'' Granado said, adding that the pipeline was "nearing completion in Iowa.''

Iowa farmer David Lowman said he's frustrated that workers burned a pile of walnut tree branches on his land. He said the company had promised to leave the pile so he could sell it for firewood.

"They burned up $10,500 worth of firewood,'' Lowman said. "They didn't do what they said they were going to do.''

Cyndy Coppola said workers left behind several 30-inch steel rings and other debris when they stalled a section of pipeline across her land in Calhoun County.

"I guess our biggest complaint is they show no respect,'' said Coppola, 68, who was arrested for trespassing while at a pipeline protest last month.

Inspectors said workers plan to return to Coppola's farm and clean up the site.

Most of the 18 Iowa counties in the pipeline's path have hired an outside firm to respond to complaints about the project and conduct inspections. Evan Del Val is a civil engineer with ISG, which was hired in 13 of those counties to respond to concerns.

Del Val said a lot of the complaints don't violate the construction agreements.

"A lot of complaints aren't violations,'' he said. "They're just that: They're complaints.''