AIDV: Analyte Interval Data File Format

This format allows you to specify the top and bottom elevations of well screens and one or more concentrations that were measured over that interval. This new format (.aidv) will allow you to quickly visualize well screens in post_samples and automatically convert well screens to intelligently spaced samples along the screen interval for 3D (and 2D) kriging.

Format:

• You may insert comment lines in C Tech Groundwater analyte (e.g. chemistry) (.aidv) input files.

  • Comment lines must begin with a ’#’ as the first character of a line.

Line 1: You may include any header message here (that does not start with a ’#’ character) unless you wish to include analyte names for use by other EVS modules (e.g. data component name). The format for line 1 to enable chemical names is as follows

A. Placing a pair of ’@’ symbols triggers the use and display of chemical names (example @@VOC). Any characters up to the @@ characters are ignored, and only the first analyte name needs @@, after that the chemical names must be delimited by spaces,

B. The following rules for commas are implemented to accommodate comma delimited files and also for using chemical names which have a comma within (example 1,1-DCA). Commas following a name will not become a part of the name, but a comma in the middle of a text string will be included in the name. The recommended approach is to put a space before the names.

C. If you want a space in your analyte name, you may use underscores and EVS will convert underscores to spaces (example: Vinyl_Chloride in a .aidv file will be converted to ’r;Vinyl Chloride." Or you may surround the entire name in quotation marks (example: "Vinyl Chloride").

The advantages of using chemical names (attribute names of any type) are the following:

• • many modules use analyte names instead of data component numbers,

  • when writing EVS Field files (.eff, .efb, etc.), you will get analyte names instead of data component numbers.

  • when querying your data set with post_sample’s mouse interactivity, the analyte name is displayed.

  • time-series data can be used and the appropriate time-step can be displayed.

Line 2: Specifications

• Elevation/Depth Specifier: The first item on line 2 must be the word Elevation or Depth (case insensitive) to denote whether well screen top and bottom elevations are true elevation or depth below ground surface.
• Maximum Gap: The second parameter in this line is a real number (not an integer) specifying the Max-Gap. Max-gap is the maximum distance between samples for kriging. When a screen interval’s total length is less than max-gap, a single sample is placed at the center of the interval. If the screen interval is longer than max-gap, two or more equally spaced samples are distributed within the interval. The number of samples is equal to the interval divided by max-gap rounded up to an integer.
• • [note: if you set max gap too small, you effectively create over-sampling in z (relative to x-y) for your data.  On the other hand, if you have multiple screen intervals with different z extents and depths, choosing the proper value for max-gap will ensure better 3D distributions.  If max-gap is set very large, only one sample is placed at the center of each screen interval.  If the screens are small relative to the thickness of the aquifer, a large max gap is OK.  If the screens are long (30% or more) of the local thickness and there are nearby screens with different depths/lengths, you will need a smaller max-gap value.  Viewing your screen intervals with the spheres ON will help assess the optimal value.
• Coordinate Units: After Depth/Elevation, include the units of your coordinates (e.g. feet or meters)

Line 3: Specifications

• The first integer (n) is the number of well screens (rows of data) to follow. You may specify "All" instead to use all data lines in the file.
• The second integer is the number of analyte (chemistry) values per well screen.
• The units of each data analyte column (e.g. ppm or mg/l).

Line 4: The first line of analyte interval (well screen) data must contain:

• X

• Y

• Well Screen Top

• Well Screen Bottom

• (one or more) Analyte Value(s) (chemistry or property)

• Well or Boring name.  The boring name cannot contain spaces (recommend underscore "_" instead).

• Elevation of the top of the boring.

Boring name and top are are optional parameters, but are used by many modules and it is highly recommended that you include this information in your file if possible. They are used by post_samples for posting tubes along borehole traces and for generating tubes which start from the ground surface of the borehole. Both 3d estimation and gridding and horizons will use this information to determing the Z spatial extent of your grids (gridding and horizons will create a layer that begins at ground surface if this information is provided). Numbers and names can be separated by one comma and/or any number of spaces or tabs.

BLANK ENTRIES (CELLS) ARE NOT ALLOWED.

Please see the section on Handling Non-Detects for information on how to deal with samples whose concentration is below the detection limit. For any sample that is not detected you may enter any of the following. Please note that the first three flag words are not case sensitive, but must be spelled exactly as shown below.

• Prepend a less than sign < to the actual detection limit for that sample. This allows you to set the "Less Than Multiplier" in all modules that read .apdv files to a value such as 0.1 to 0.5 (10 to 50%). This is the preferred and most rigorous method.

• nondetect

• non-detect

• nd

• 0.0 (zero)

For files with multiple analytes such as the example below, if an analyte was not measured at a sample location, use any of the flags below to denote that this sample should be skipped for this analyte. Please note that these flag words are not case sensitive, but must be spelled exactly as shown below.

• missing

• unmeasured

• not-measured

• nm

• unknown

• unk

• na

Example Files are here: