&I West Lake Update
AiifTiist 7.7. 9.014	X
August 27, 2014
This issue of West Lake Update is focused on Lead-210
and corrects misinformation about studies conducted by
the U.S. Army Corps of Engineers at sites in Ohio.
General Information
Lead-210 is a decay product of Radon-222 and Ura-
nium-238 and has a half-life of 22 years. (Half-life is
the time required for one half of the chemically unstable
material to degrade into a more stable material.) El-
evated Lead-210 in soils is not uncommon due to natural
processes, including radon daughter washout from rain
events and accumulation over time. As a result, slightly
elevated levels of Lead-210 are commonly found in low-
lying areas where rain collects and concentrates, such as
tne drainage ditch at the Bridgeton Municipal Athletic
Complex (BMAC). Lead-210 levels up to 20 picocuries
per gram (pCi/g) or higher can be found when analyz-
ing soil and sediment samples collected from such areas.
Appendix B of EPA's Multi-Agency Radiation Survey and
Assessment of Material and Equipment (MARSAME)
manual provides more information online at: www.epa.
Radon Daughter Washout Process
The radon daughter washout process, through which
rain naturally collects radon decay products, is a known
and well-studied natural process. In fact, Lead-210
accumulation and radiometric dating is an established
technique used in geology to determine the age of depos-
ited material. The illustration below depicts the washout
'Mh of i*)tupporte