Notes from the Utah Division of Drinking Water

From: Rachael Cassady <rcassady@utah.gov>
Date: Wed, Dec 12, 2012 at 11:33 AM
Subject: Radium-228

Here are the main points about radium-228 in the RPC drinking water system:

 1.  The radium-228 quarterly sampling was triggered by one sample that was over the 5pCi/L MCL.  This sample was in August 2011 and the result was 6.5pCi/L.

2.  After quarterly sampling is triggered then we need four quarters of data before we can determine if there is an MCL violation.  See Rule R309-205-7 for reference (http://drinkingwater.utah.gov/documents/rules_ddw_version/R309-205_9-24-09.htm#_Toc251079942).

3.  After we have data that covers all four quarters of the year we can then determine if we have an MCL violation.  If you don't have an MCL violation the rad sampling goes back to normal.  If you do have an MCL violation for radium-228 then it is a tier 2 violation which requires public notice and remedy of the problem.  In this case you're looking at treatment or blending if blending is possible. 

4.  Here is your radium-228 data how it looks now ...
August 2011 6.5pCi/L,
October 2011 4.4pCi/L,
February 2012 4.6pCi/L,
June 2012 8.8pCi/L.  

I'd like to at least get minimum one more data point before we average because I typically do not use that initial sample in the averaging.  I'm concerned that there is such a wide fluctuation between the 4's and the 6-8's so it will be good to get one more to see.  I did advise you on the phone to sample again Jan-Feb 2013, but this is optional if we determine after the sample you take this week throws the average over the MCL. (Although, the more data points we have that are below 5pCi/L the better the average ends up being.  Something to keep in mind.)

5.  It might be a good idea to do a little research on possible treatment and/or blending options.  Let me know if you need help with this, I have one other system that has done a blending treatment option for radium-228.

Let me know if you have other questions or need more information!

thanks,

Rachael Cassady
Environmental Scientist
Utah Division of Drinking Water