Site Description
The Savannah River Site (SRS), one of 16 major defense-related facilities in the U.S. Department of Energy (DOE), is located on 325 square miles on the Savannah River approximately 25 miles from Aiken, South Carolina. Operations at SRS are grouped into six areas: reactor areas (C, K, L, P, and R); separations areas (F and H areas); waste management areas (G, S, Y, and Z areas); the Heavy Water Reprocessing Area (D area), the Reactor Materials area (M area); and the Administration Area (A area). Roughly 500,000 people live within a 50-mile radius of the facility. (WSRC-IM-91-28 - Volume 1 - Savannah River Site - Environmental Report).
SRS is located on a geological formation known as the Upper Coastal Plain. This formation consists of 500 to 1,400 feet of generally sandy sediments containing several productive aquifers. These aquifers tend to be separated by clay-rich aquitards, causing significant lateral movement of groundwater to the Savannah River, its tributaries and the Savannah River Swamp. Older underlying rock (metamorphic and igneous) are considered nearly impermeable. DOE has identified 56 major municipal, industrial and agricultural groundwater users within roughly 20 miles of SRS, including four schools in 25 small communities.
Five major streams on SRS serve as tributaries to the Savannah River. Two municipal water treatment plants downstream currently supply 71,000 people (Environmental Information Document, L-Reactor Reactivation, DPST-83-470). Expansion plans call for 300,000 people to be served by the year 2000 from this surface water resource.
Major Environmental Concerns
Designed to produce nuclear materials for national defense, its historical mission has resulted in on-site disposal of hazardous, transuranic, low and high-level radioactive, and mixed waste. At present, 266 waste management units have been identified at SRS, containing materials ranging from nonhazardous waste to liquid high-level radioactive mixed waste. Migration of contaminants from seepage and settling basing, unlined disposal pits, waste piles, and underground storage tanks has caused significant contamination of soil and groundwater (DOE/EM-0050P - EM Fact Sheet).
F and H areas, located near the center of SRS, contain chemical separation facilities used to process reactor-produced radioactive materials. The F and H areas and the Radioactive Waste Burial Grounds are located on a "groundwater divide" with flow in two directions. Four Mile Creek and Upper Three Runs Creek receive near-surface groundwater from these areas. Seepage Basins (unlined excavations designed to allow mixed radioactive waste to percolate downward into the earth) in the F and H areas have received low-level radioactive chemical waste including acids, mercury and sodium hydroxide for over forty years.
Both area basins have caused groundwater contamination with radium, tritium, strontium, chromium, mercury, lead and cesium. One measure of radioactivity in the groundwater (nonvolatile beta activity) below the seepage basins exceeds state standards by 460 times. Maximum levels of radionuclides and chemical contaminants occur in the aquifer below the seepage basins and immediately downgradient of the basins (WSRC-IM-91-28). Three water zones below the H area seepage basins (200 to 300 feet) have been impacted. The contaminant plume extends both upgradient of the basins, and downgradient to the northern reach of Four Mile Creek. In 1990 approximately 14,500 Curies of tritium were released to the Savannah River by these and other pathways.
Solution to Major Concerns
RKK, Ltd. can immediately install its CRYOCELL containment methodology to completely isolate the F and H area Seepage Basins. All chemical and high level waste present at this site can be stopped from leaching further into surrounding soils and into the two aquifers directly under the site. CRYOCELL is the only containment system available today that provides diffusion free, monitorable, full containment and isolation, that is removable and repairable in-situ. No other technology available today can compare to or provide these design standards for mixed or high level waste containment. Should contaminated soil and shallow groundwater be removed or treated in-situ, groundwater control and excavation support is allready provided by a CRYOCELL barrier. CRYOCELL would effectively eliminate contaminant releases into Four Mile Creek and Upper Three Runs Creek.
CRYOCELL engineering is site specific. RKK's Thermodynamic Model-ing/Monitoring Program incorporates all site characteristics into a three dimensional model which RKK uses to design and estimate costs of CRYOCELL, and to develop a real-time computer image of barrier status throughout its life-cycle. RKK's modeling/monitoring program provides the ability to detect irregularities and quickly return the barrier to acceptable performance limits based on the model observation.
Cost to Address Major Concerns
A conservative total site cost for a CRYOCELL barrier fully containing the the four H-Area Seepage basins for 30 years is estimated at $15.5 million. This barrier can be installed and fully functional within 12 months of a request to proceed. Cost per square foot for a CRYOCELL barrier isolating the four H-Area Seepage Basins is approximately $12.17.
Compared to slurry wall "containment" at an installation cost of $14.89, CRYOCELL clearly provides economic as well as technical advantages. Slurry wall "containment" cannot provide a bottom, diffusion free containment, or on-line/real-time barrier monitoring throughout the installation's life cycle. Removal costs for slurry walls can exceed initial installation costs as they become contaminated over time; removal costs are estimated at $42.60/sf. RKK is poised to provide immediate containment of all eight Seepage Basins.
By acting now, waste migration can be effectively halted allowing more time for development of technical and political solutions to remediate the serious environmental concerns at Savannah River.