Does anyone have any information on this inquiry?  His question is whether any EPA regions/state/localities have addressed the issue of when a sample comes back "non-detect," whether they must apply EPA policy that establishes mass loading at one-half the detection limits.  Brian mentions that this policy assumes that flows contain polluant loadings that may not be present, resulting in overregulation.  Please respond to Brian directly at [log in to unmask]    

Thanks in advance.


Holly Lynch
IPC Director of EHS Programs

----------
From: 	Brian Thomas[SMTP:[log in to unmask]]
Sent: 	Tuesday, March 18, 1997 10:07 AM
To: 	Holly Lynch
Subject: 	Re: Detection limits - Water Quality

Greetings:

I am wondering if any other areas are battling the issue regarding 
detection limits as it relates to compliance and Mass Loading.  

As you may know we have been working this issue for the South San 
Francisco Bay for several years.  At this time for both point and 
nonpoint sources the current state of the practice is to take 1/2 of 
the detection limit if the sample analysis comes back Non Detect.  

For industrial discharge with high flows the resultant mass loading 
by taking 1/2 the detection limit accounts for Mass which may or may 
not be present.  Lower detection limits through more costly 
analytical methods are the typical response on this issue from 
Regulatory entities.

This approach is also becoming an issue with regard to storm water 
runnoff.

Please let me know if you know of any EPA or Local work in this area.

Regards,
       Brian Thomas
       Sigma Circuits, Inc./Printed Circuit Alliance
       408-727-9168 x 106



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