OAK RIDGE NATIONAL LABORATORY
WASTE AREA GROUP 4
HAZARDOUS WASTE ENCAPSULATION

Oak Ridge, Tennessee

The site located in Oak Ridge, Tennessee was one of the former waste disposal areas for nuclear, toxic and hazardous wastes. Shallow waste trenches were excavated in the rock and contained the wastes. Groundwater migrating through the waste trenches would inevitably transport radioactive isotopes to the nearby waterways. The removal action project initiated was designed to encapsulate the wastes within 4 trenches thereby mitigating radioactive isotope migration into nearby waterways. A combination of the use of both chemical and cementitious grouts was specified for the project.

This unique project presented some challenges upfront. The site was considered a hazardous waste site and the extent of the buried wastes was indeterminate. Several proactive safety precautions were incorporated into the production work including the use of semi-remote controlled Tube-a-Manchette (TAM), or sleeve port grout pipe, installation equipment, along with Industrial Health and Safety personnel oversight of all work activities. All personnel at the site were required to complete 40 Hour HAZWOPER and RadWorker training.

A three step injection process was used to complete the project. First a cementitious grout consisting of type 3 portland cement, bentonite, viscosity modifier, pozzolans, fly ash, grout retarder and silica fume was injected into each zone followed by injection with microfine cement. The final grouting pass in each zone was performed using acrylamide chemical grout to ensure maximum encapsulation of the waste.

Real time computer monitoring of grouting operations was completed using an xy-recorder and a personal computer. The insitu hydraulic conductivity was reduced to a value of 1x10-6 cm/s.

Client: US Army Corps of Engineers, Louisville District

Owner: US Army Corps of Engineers, Louisville District