Sustainability Drives Innovation, Cost Savings at Saltstone Disposal Unit 6
By: Tam Nguyen, Corporate Manager for Sustainability
The U.S. Department of Energy (DOE), a longtime Bechtel customer, has the mission to safely clean up the environmental legacy from decades of producing nuclear materials for national defense. And for decades, Bechtel colleagues have partnered with DOE to achieve that mission, leaving a safer environment for communities and future generations.
At DOE’s Savannah River Site in Aiken, S.C., Bechtel and the other top organizations that comprise Savannah River Remediation, LLC helped deliver Saltstone Disposal Unit 6 (SDU6), a first-of-its-kind, 32-million-gallon (124-million-liter) tank created to permanently store treated, low-level radioactive waste from 43 aging, underground tanks at the site. SDU6 is the largest rubber-lined tank in the world, holding the equivalent of nearly 50 Olympic-sized swimming pools. The waste is mixed with a concrete-like substance and poured into the tank, immobilizing it for safe storage.
While the delivery of the tank itself was the ultimate goal, a sharp focus on sustainability throughout the design, engineering, and construction of the tank drove innovation and led to a range of added benefits.
Early in the construction process, we used 2D thermal modeling to better predict temperature gradients, allowing for the elimination of exterior insulation, which saved $1 million USD.
Throughout the project lifecycle, we also secured and protected critical water resources by:
- Reducing expensive domestic water usage by more than 90 percent.
- Conducting first-of-a-kind hydrotesting using a fluorescent dye for leak detection at concentrations safe for environmental release.
- Returning more than 60 million gallons (227 million liters) of water from hydrotesting to the underground water supply through carefully chosen discharge locations, enhancing local habitats.
In addition, we reduced waste disposal by reusing 55,000 square feet (5,109 square meters) of insulation material and 1,500 gallons (5,678 liters) of chemical product.
Reaffirming our commitment to the local community, we trained 20 craft painters from the Augusta building trades to install rubber liner material. With the skills and training acquired during their tenure on SDU6, these union members are now available to support other projects in the region, including hurricane recovery efforts in the Carolinas and Florida.
Overall, our sustainable efforts to support construction of SDU6 allowed our customer to achieve more than $500 million USD in lifecycle savings. Ultimately, our partnership on SDU6 earned recognition as the U.S. Department of Energy’s Project of the Year Award.
Supporting DOE’s ongoing mission at the Savannah River Site, we are now applying these innovations and lessons learned to help build three additional tanks similar to SDU6.
Through innovative and sustainable efforts such as those employed at the Savannah River Site, we can continue to help customers achieve their goals more efficiently, safely, and with minimal impact to the environment.
