Characterization of surface soils at a former uranium mill

Area of Science:

• Environmental Science
• Geoscience
• Nuclear Engineering

Background:

• The Dawn Mining Company operated a uranium mill in Stevens County, Washington, processing ore and later extracting uranium from mine water treatment sludge.
• Site operations spanned from 1957 to 1982 and 1992 to 2000, with permanent closure and license amendment in 2001.
• The mill building was demolished in 2003, preceding site soil characterization in 2004.

Purpose of the Study:

• To characterize contaminated soils at the former Dawn Mining Company uranium mill site.
• To develop an efficient and accurate method for guiding remedial action planning and soil cleanup.
• To establish a correlation between gamma exposure rate and radium concentration in soils.

Main Methods:

• Utilized a GPS-based gamma scanning system for surface soil characterization.
• Developed a correlation between shielded gamma exposure rate and radium (Ra) concentration in surface soils.
• Employed backhoe trenches for subsurface soil sampling.

Main Results:

• The GPS-based gamma scanning system proved efficient and accurate for site soil characterization.
• A reliable correlation was established between gamma exposure rate and radium concentration in surface soils.
• The characterization methods effectively guided the development of remedial action plans.

Conclusions:

• GPS-based gamma scanning is an effective tool for characterizing uranium mill sites.
• Accurate soil characterization is crucial for successful remedial action planning and cleanup.
• The methods employed facilitated efficient and accurate soil remediation at the Dawn Mining Company site.