International Dredging Review

International Dredging Review

Ten months after 5.4 million cubic yards of wet fly ash burst an earthen containment pond owned by the Tennessee Valley Authority and spilled into the Emory Clinch and Tennessee Rivers and across 300 acres of land at Kingston Tennessee the cleanup is making good progress and has removed more than 1.5 million of the three million cubic yards of ash from the Emory River. The effort is headed for a target date of having all ash out of the river by April 2010.

The cleanup is a joint partnership between the TVA the federal EPA and the Tennessee Department of Environment and Conservation (TDEC). Personnel on site include about 400 TVA and contractors one from TDEC and 10 from EPA. The prime dredging contractor is Sevenson International. Muctec has the contract to load the ash into oil cans.

Trans Ash (which was sold to Choo Choo Dredging Company in 2008) was hired on an interim basis working from March 20 through the end of July. The unprecedented volumes of ash challenged Trans Ash’s 12-inch pumps.

“We knew we would need bigger dredges to meet our targets” said John Moebes. Moebes a former long-time EPA official is a program manager with Jacobs Engineering whose job is to supervise and coordinate the contractors on the cleanup.
Sevenson’s approach to the job was to use a combination of dredge and pump sizes. They bought a new Ellicott 670 dredge with a 46-foot ladder and subcontracted with L.W. Matteson for their 20-inch dredge Little Rock. Later in the project Sevenson mobilized a 16-inch Ellicott 1170 dredge and Matteson replaced the 20-inch Little Rock with the 20-inch Sandpiper.

Sevenson is now operating with their Ellicott 670 and Matteson’s Sandpiper. The Sevenson 14-inch dredge is in backup in case one of the primary dredges goes down.

“Using all three dredges at once would give us more water than we could handle” said Moebes.

The goal is to pump about 12500 cubic yards per day although on the day before we spoke Moebes said they moved about 15500 cubic yards. Production has been as high as 21000 cubic yards per day with the 20-inch and 16-inch dredges operating on two 10-hour shifts per day six days a week with Sundays for maintenance and repairs.

Booster pumps are used on the two smaller dredges; the larger one doesn’t need one.

“We’re trying to get it all out of the river as well as everything east of Dike Two by early April” said Moebes. “The goal is to ship one 85-car train seven days per week every week.”

All of the wet fly ash is being shipped to Perry County Alabama where it will be placed in a landfill.

In the meantime keeping the dust minimized is job one. Besides being kept wet the ash is covered with a substance including grass seeds and nutrients that grows into a turf to keep it in place and prevent dust until it is moved.
Work was temporarily halted in midsummer as the job transitioned to Sevenson and the U-shaped ditch that received the discharge from all the dredges called a rim ditch was reconfigured. Sheet piling was placed along the 1800 feet of the ditch’s walls to increase its capacity and improve safety. Matteson’s dredge began work at the beginning of August.

Superfund Law Provides Protection Scrutiny
In May the EPA placed the Kingston site under the Comprehensive Environmental Response Compensation and Liability act (CERCLA) better known as the Superfund law. One effect of that is to block legal challenges to the cleanup. But it also means that EPA has an on-site coordinator of the effort.

The Kingston cleanup effort has been placed under an unusual amount of public scrutiny including a 60 Minutes special that aired October 4 and an upcoming 48 Hours special.

While TVA has placed a great deal of detailed information on its Kingston cleanup site ( several sources contacted for this article didn’t want to go on the record. Some subcontractors said they had been told not to talk to the media.

There has been speculation in the press that the EPA may be about to declare fly ash a hazardous substance something that some environmentalists would like it to do. But previous Administrations turned down two opportunities to do so.

Depending on the type of coal burned to create it some fly ash can contain trace amounts of some materials like selenium cadmium boron cobalt lead and arsenic.

The American Coal Ash Association which has been promoting the use of fly ash and other coal combustion products since it was established in 1968 claims that fly ash has almost exactly the same composition as volcanic ash. When it is used to strengthen concrete any trace elements are bound and neutralized.