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Drew Clemens

Managing and Appropriately Using Non-Detect Chemistry Results (RW17)

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What is the best/a good way to address non-detects so follow-on contour plots do not misrepresent the T-data set?

I am preparing to import lab chemistry results from a long term monitoring program to generate contaminant contour maps. Most of our results are non-detects, several are J-values below the detection limit, and some wells were not sampled due to lack of water (water levels are the only data collected). Fields for missed samples can be left blank. Entering a zero is misleading for non-dected results, and will bias contour plots. I have toyed with the idea of entering the detection limit (variable across sample sets and dates), then applying a lower bound to the data countours at the map-making stage. What other work arounds have the community used?

Thank you in advance for your time,

Drew

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Hi Drew,

Some customers use half the non-detect for values that are below the detection limit but not zero.

Regards,

Tom B

RockWare Inc

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Drew, it sounds like I'm working on a similar project right now that you were in December of 2015. I'm trying to show contamination levels in cross sections. Where's the best place to insert data in Rockware that we've received TomB?

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Hi rdthoss,

Contamination data are often entered in the I-Data table for each borehole, or imported from an Excel file using the I-Data table format listed in the help.

Regards,

Tom B

RockWare Inc

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