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Groundwater Professional Bulletin Board POSTED: 08/21/2000USE OF FREE PRODUCT DEFAULTS IN THE TIER 2 SOFTWARERecently the department discovered a problem with data handling in the software regarding the use of free product defaults. When free product defaults are entered more than once for a sampling location, and then measured concentrations which are lower than the defaults are entered, the software inappropriately assigns the measured concentration to the location. This occurs because the software recognizes these values as meeting the steady and declining criteria. For example:
In this case, the software assigns 800 ppb to the sample location. This could result in misidentification of the groundwater maximum for the site, as well as the groundwater source location. To address this problem you should use the free product defaults for only one sampling event when product is present. Either enter the defaults one time or chose ignore for previous free product samples. Remember, in order to replace free product defaults with actual data, the well must
be sampled twice subsequent to when product was last noted. Sampling events must be
separated by six months. If a well currently has free product, it must be sampled and
analyzed for chemicals of concern and those analytical results are be used in the /
Tier 2 evaluation (i.e., two sampling events are not needed for a well which presently
has free product). If this is the case, free product defaults should not be entered in
the software. Refer to Section 2.5 of the Tier 2 Guidance for procedures on sampling
wells with free product.
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