BISMARCK, N.D. (AP) — The Standing Rock Sioux have requested a hearing on a plan by the developer of the Dakota Access Pipeline to double the line’s capacity, a move the tribe believes multiplies the risk of an oil spill.

Doubling the pipeline’s capacity increases the “consequences as well as the likelihood” of an oil spill, Tribal Chairman Mike Faith said in a letter to state regulators.

Texas-based Energy Transfer announced in June it plans to expand the pipeline’s capacity from more than 500,000 barrels per day to as much as 1.1 million barrels. The pipeline has been moving North Dakota oil through South Dakota and Iowa to a shipping point in Illinois since June 2017.

The $3.8 billion pipeline is less than a half mile from the Standing Rock Reservation, beneath a Missouri River reservoir that is the tribe’s water source.

Fears of an oil spill into the river sparked
massive protests
in 2016 and 2017, drawing thousands of pipeline opponents to North Dakota.

The company said the expansion would help meet the growing demand for oil from North Dakota, the nation’s second-biggest oil producer behind Texas.

Energy Transfer is proposing additional pumping stations in the Dakotas and Illinois. The company needs permission from the North Dakota Public Service Commission for the expansion because some of the land needed is outside of the pipeline’s path.

The three-member panel
agreed
last month to consider a hearing on the expansion if one was formally requested. The tribe was the first to submit a request before the Friday deadline.

PSC spokeswoman Stacy Eberl said the three-member panel would evaluate requests before making a decision on whether to hold a public hearing.

Wayde Schafer, spokesman for the state’s Sierra Club chapter, said his group will submit a formal request for a public hearing later this week.

“This pipeline affects a lot of people and not holding a public hearing just doesn’t make any sense — it’s actually idiotic given all everyone has already gone through on this,” Schafer said.