Santee Cooper has removed 42,000 tons of coal ash from ash lagoons at its old Grainger Generating Station near Conway.
The Southern Environmental Law Center said Wednesday the information is contained in a report released this week.
Last year, the center reached an agreement to have the utility remove 1.3 million tons of ash from the plant site on the Waccamaw River. The center had sued on behalf of environmental groups claiming the lagoons discharged arsenic into the groundwater and river.
The SELC said at the current rate, the ash will be removed within six years, well ahead of the 10 years required in the settlement.
The ash is used in the manufacture of concrete and an ash recycling center is scheduled to open in nearby Georgetown County.