Re: Info request: lead cleanup

[Deborah Dixon Walker (E-mail 3) <dcdixon@pobox.com>]

Re Posting from Jim Woolford (JW), my comments prefaced with DDW>>:

JW>> I am surprised to see these levels. They are well below the 400 ppm 
JW>> soil screening level for CERCLA and the proposed 400 ppm "level of
JW>> concern" in the proposed TSCA 403 regulation. I won't say there are
JW>> no Superfund sites with cleanup levels this low, but if there are any,
JW>> there are only a few.

DDW>> The trend in remedial investigations I have worked on was to use
DDW>> either 400 ppm or a number based on blood lead modeling for site 
DDW>> specific conditions. Potential future land uses were major factors.

JW>> If not too much a problem, I'd like to find out how these levels were
JW>> developed.

DDW>> Me too!

JW>> On the technology front. As far as I know the use XRF (X-ray
JW>> floresence (sp?) ) technology is a good candidate technology.

DDW>> Re: x-ray fluorescence (XRF) -- I have used this technique to do
DDW>> preliminary assessment at three different sites of varying
DDW>> characteristics. The manufacturer claimed detection limit
DDW>> was 10 ppm at that time. The practical quantitation limit we
DDW>> used was 50 ppm, as I recall. So, in a 400 ppm situation, the 
DDW>> technique is probably sufficiently accurate to use for initial 
DDW>> quantitation (depending on site data quality objectives and based
DDW>> upon successful laboratory confirmation of a percentage of the 
DDW>> results). However, for the 30 ppm situation, unless there has been
DDW>> a significant improvement in the last 2-3 years, I
DDW>> wouldn't want to recommend the technique.

Deborah Walker
dcdixon@pobox.com

The opinions stated above are strictly my own and are not to be interpreted
as the positions of my employer or anyone else on this or any other matter.