Drilling shows aquifer lies beneath refinery site

August 2008

U.S. Water News Online

ELK POINT, S.D. — A state geologist says he's not worried by an aquifer that underlies all or most of the site for a planned $10 billion crude oil refinery.

Derric Iles says a team that's been drilling test holes has found a highly impermeable "protective layer of till" — a deposit of fine clays and silts — between the Lower Vermillion-Missouri Aquifer and the surface. That layer would make it difficult for substances to leak through it, he told the Sioux City Journal.

"For that reason, I don't view activity at the land surface, such as the proposed energy center, as posing a threat to the lower aquifer," Iles said. "That's just my opinion. We have to do the drilling and install the permanent ground water monitors."

The team has been drilling test holes for permanent monitoring wells in the area where Hyperion Refining wants to build a 400,000-barrel-a-day refinery.

Iles said the monitors will provide data showing whether his opinion is warranted.

Drilling started in mid-July but was interrupted by an equipment breakdown. It's expected to continue for another week as the team tries to better define the aquifer. At least three monitors are planned to be more than 200 feet deep.

The South Dakota Department of Environment and Natural Resources is reviewing Hyperion's application for an air-quality permit.

Last month Hyperion project executive Preston Phillips said the company expects the application to be ready for a 30-day public comment period later this summer.

But Kim Smith, a DENR spokesman, said his department's engineers were not ready to predict when it would be ready.