Deep injection well sought for oil wastewater in southwest SD
RAPID CITY, S.D.—A proposal to dispose of oil-production wastewater by injecting it 3,160 feet underground in the southwestern corner of South Dakota appears headed for approval after several people who contested the application did not show up for a hearing Thursday, Oct. 18, in Pierre.
The application for an injection permit came from Peter K. Roosevelt of Denver, who already operates six oil production wells and three disposal wells in Fall River County and wants to begin producing oil from another well.
Oil wells produce not just oil but also briny water. To dispose of the water from his new production well, Roosevelt wants to convert a nearby exploratory well into a disposal well. There are already 18 such disposal wells in South Dakota, including four in Fall River County, 13 in Harding County and one in Custer County.
Roosevelt's application for an injection well was opposed by several people, including ranchers who sent letters to state regulators expressing fears that an injection well might contaminate their water wells. The letters triggered a public hearing Thursday morning at the Joe Foss Building in Pierre, where none of the opponents were in attendance.
At the hearing, the nine-member Board of Minerals and Environment, which is appointed by the governor, heard testimony from a geologist retained by Roosevelt and from an expert who works for the state Department of Environment and Natural Resources. Both said the few water wells near the proposed injection well would be safe from contamination.
Geologist Dennis Johnson of Rapid City said the nearest water well is 3 miles from the proposed injection well, and the underground geology is such that the injected wastewater would not migrate into aquifers that supply water to ranches, residences and livestock in the sparsely populated area roughly 30 miles southwest of Edgemont.
"The sand they're injecting into has several beds above and below it within close proximity that would preclude any movement up and down in the section," Johnson said.
Brian Walsh, of the Department of Environment and Natural Resources, gave similar testimony.
"It's my opinion that the proposed injection well will not have an impact on the intervenors' wells," Walsh said.
The water wells in the area draw from the bottom of the Minnelusa formation, which is below the injection zone, and also from the Inyan Kara formation, which is above the injection zone, Walsh said in a later interview.
The injection permit would allow Roosevelt to inject water through concrete-surrounded steel casing at pressures up to 550 pounds per square inch for 30 years or a total of 8.21 million barrels, whichever comes first. That number of barrels equates to about 345 million gallons.
"Neither one of those will probably ever be reached, unless Mr. Roosevelt gets lucky and finds a lot more production in that area," Johnson said.
There would be numerous other conditions on the permit, including a maximum daily injection rate of 750 barrels, and a required mechanical integrity test followed by re-testing at least every five years. Roosevelt has posted a $30,000 statewide bond, which state regulators could capture and apply to the cost of plugging the well and reclaiming the surface if Roosevelt does not fulfill his obligations.
Besides needing permission to operate the injection well, Roosevelt also needs an aquifer exemption from state government and the federal Environmental Protection Agency. That's because the injection zone contains water that might otherwise be suitable to tap for drinking water. It's unlikely the water in the injection zone will ever be needed for water wells, according to testimony offered Thursday, partly because so few people live in the area.