Services Rendered:

Hydrologic Modeling

Groundwater Monitoring

FEMWATER Modeling

HELP2.0 Modeling

Design Support

Erosion Control

Water Balance Study

Seepage Analysis

Environmental Impacts

Client:

Department of Energy, Tennessee, USA

Status of Project:

Completed

DSI provided hydrologic, hydraulic and environmental engineering support for the development of the Conceptual Design Report (CDR) for the Low-Level Waste Disposal Facility (LLWDF). Two disposal facilities are proposed to be constructed, a Class I Disposal Facility located on West Chestnut Ridge, and a Class II Disposal Facility located in West Bear Creek Valley. The Class I facility consists of impermeable synthetically lined trenches with approximately one year of disposal capacity for each trench. The Class II facility utilizes the Tumulus concept of above-grade concrete pads with waste encapsulated in concrete vaults.

Conducted water balance studies to determine the impact of post-development runoff on surface waters with respect to water quantity, water quality, and sediment transport. Conceptually designed the final covers and in-trench run-on/run-off controls to cost effectively minimize the waters which require treatment. The Leachate Treatment Facility (LTF) and associated equalization/holding tanks were sized through a detailed routing, storage and trench filling analyses. The HELP 2.0 model was modified to obtain detailed daily flow rates which were input to a DSI water budget program. A 30-well monitoring network was designed. Nested wells were used to assess vertical movement of potential contamination. Intra-trench runoff and run-on pumps were sized via complete hydrograph routing.

Hydrologic and groundwater modeling was conducted to size the leachate collection system pumps and the below-liner pumps, respectively. The groundwater model FEMWATER was used to determine the storm flow and unsaturated zone flows into the below-liner sumps. Hydrogeologic characterization data for West Chestnut Ridge site was utilized in the modeling studies.

Aerial view of LLWDF (courtesy DOE, Oak Ridge)

Aerial view of LLWDF (courtesy DOE, Oak Ridge)