Static Water Level

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Static Water Level is the level of water in the well or piezometer before the slug is injected or withdrawn. Frequently, drawdown in the well is measured in the field, but it is the head change (the difference from drawdown and static water level) that is required for the slug test analysis. Drawdown and static water level must be entered relative to the same datum.

If the data logger file is loaded first, or no value of static water level is entered, Super Slug automatically calculates a value for static water level based on the minimum drawdown for decreasing drawdown values, or the maximum drawdown for increasing drawdown values.

Two phenomena must BOTH occur to make the calculated value of static water level incorrect.

1. The data logger readings began slightly after the injection or withdrawal of the slug.

2. The water level did not return to static water level before the data logger was turned off.

During Super Slug development and testing, actual test data sets were encountered where both of these events occurred. It is very important to record the actual static water level before a slug test begins. An incorrect value for static water level will result in an incorrect determination of hydraulic conductivity.