Fifteen years ago the Northern States Power Plant located on the east edge of Granite Falls incinerated its final load of coal.
Over the past month the plant’s parent owner, Xcel Energy, has initiated the clean-up of the last remnants of the coal ash, which have been stored in four containment ponds located adjacent to the plant.
Xcel Energy Project Manager Darin Schottler, said that the company is currently filing a plan to remove all of the ash with MPCA. If the plans are approved, the four pools are expected to be dredged and closed sometime in 2011.
Schottler called the current effort, which only involves the first of the four ponds, a pilot project due to current uncertainties relating to the state of the coal ash. The project manager said that the company is not sure what it will require to remove the ash given the composition of east and western coal in addition to the length of time that it has been sitting. The pilot project will help determine requirements to be detailed in the removal plans.
Whatever the makeup of the ash, Schottler said that it is expected to take several hundred truckloads to remove all of the remains from the site. According to information contained in an EPA freedom of information request from May of 2009, the first two pools, installed during an expansion of the original plant in 1950, are approximately 12 feet deep and have a volume of 12,000 cubic yards. The third and fourth pools, installed in 1975, have a depth of approximately 9 feet with a volume of 10,800 cubic yards.
Schottler said that Xcel’s decision to clean up the ponds is due in-part to the company having come to the conclusion that it will never again consume coal at the location but also because of the growing potential that coal ash will be regulated at the federal level. The EPA is expected to begin month long hearings considering potential regulations this week.
The attention directed toward the coal byproduct intensified following the largest coal ash spill in the country’s history when a storage pond gave way in Tennessee and released 5.4 million cubic yards, or one billion gallons, of the toxic sludge, which inundated hundreds of acres and entered a nearby river.
Federal studies have shown coal ash to contain significant quantities of heavy metals like arsenic, lead and selenium that can cause cancer and neurological problems. There are approximately 900 coal ash storage sites located throughout the country.
On the cusp of the proceedings, the Environmental Integrity Project (EIP), Earthjustice and the Sierra Club released a report this past week identifying 39 coal-ash storage sites said to be contaminating ground and surface water. The findings supplement a report released earlier this year that fingered 31 additional locations. Included in the newest report are claims of ground water contamination at South Dakota’s Big Stone power plant, although those allegations have been refuted by the South Dakota Department of Environment and Natural Resources.
Minnesota already has some of the strictest storage regulations in the country, requiring that coal ash be deposited in lined containment ponds with earthen dams that are inspected every eight years. Those rules were put into place following a spill at the LTV Steel Plant located near Lake Superior. In that instance, a 770,000 cubic yard coal ash mound collapsed after heavy rains, covering highway 61 before reaching the lake’s waters.
According to the EPA freedom of information request, the site of the Granite Falls containment ponds have never been structurally compromised, but they were topped by floodwaters in the during the 1997 and 2001 flood, which may have allowed some ash to escape into the river.
Xcel Energy Communications Director Tom Hoen said that the ponds were inspected one or more times a week while the plant was in operation, and have been checked every two months, during non-frozen conditions, since becoming idle.
In addition, during operations in the mid 90s, an extensive hydrological study was conducted that monitored the effects on groundwater. Hoen stated by email that “the groundwater recharge from the ponds to the [Minnesota River] did not have a significant effect on the river, particularly in relation to MPCA standards.” Recent monitoring found that conclusion still valid, he added.
Ash from the site will be hauled to the MPCA-permitted disposal facility at Xcel’s large coal-fired power plant in Becker. Hoen said that backfill will replace the coal ash and water removed from the NSP plant ponds, and that frequent inspections will be held to ensure that vegetation takes hold.
As for the facility itself, Hoen said Xcel has yet to decide if the site will be used for producing electricity with natural gas or other fuels besides coal. The company is currently removing asbestos at the plant, which would be required whether the building was to be utilized or demolished.
