Associated Press - August 28, 2009 4:25 PM ET

ELK POINT, S.D. (AP) - A Dallas company looking to build a $10 billion oil refinery in southeastern South Dakota says it will renew options on more than 6,300 acres in Union County while releasing another 6,000 acres.

Preston Phillips, project executive for Hyperion Refining, says the company sent landowners letters on Friday letting them know whether their property will be optioned for another year.

The deadline for renewing the options is Aug. 31.

Phillips says the company has identified the location of the 400,000 barrel-per-day refinery and power plant and assessed other land needs, and what remains under option meets those needs.

Hyperion is still seeking permits and plans to start construction in 2011 and begin operations in 2015.