Three Dimensional GroundWater Chemistry File Example

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 (.gwc) will allow you to quickly visualize well screens in Map_Spheres and automatically convert well screens to intelligently spaced samples along the screen interval for 3D (and 2D) kriging.

You may insert comment lines in C Tech Groundwater Chemistry (.gwc) input files. Comments can be inserted anywhere in a file and must begin with a ’#’ character. The line numbers that follow refer to all non-commented lines in the file.

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 .gwc file will be converted to ’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: Elevation/Depth Specifier: This line can contain the word Elevation or Depth (case insensitive) or numbers 1 or -1 to denote whether well screen top and bottom elevations are true elevation or depth below ground surface. If actual elevations are used (a right-handed coordinate system), then this parameter should be 1; if depths below the top surface elevation are used, then this number should be -1.

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.

Optionally, you can include the units of your coordinates (e.g. feet or meters)

Note: The ability to use the words Depth or Elevation was implemented in Version 5.5 and is the preferred method. The use of 1 or &endash;1 remains for backwards compatibility.

Line 3: The first integer (n) is the number of well screens (rows of data) to follow. The second integer is the number of analyte (chemistry) values per well screen.

Optionally, you can include the units of each data analyte column (e.g. ppm or mg/l).

Line 4: The first line of well screen data. X, Y, Well Screen Top, Well Screen Bottom, (one or more) Analyte Value(s) (chemistry or property), Boring name, and elevation of the top of the boring. The boring name cannot contain spaces (recommend underscore "_" instead).

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 Krig_3D and Krig_3D_Geology will use this information to determing the Z spatial extent of your grids (Krig_3D_Geology 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.

• A fraction of the actual detection limit for that sample (best approach). Normally the fraction should be 0.1 to 0.5 (10 to 50%).

• nondetect

• non-detect

• nd

• 0.0 (zero) or

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

• -1.0e9 (this is the numeric flag that was required and used prior to Version 8.0)

Line 3+n: is the last line of the file. The line following this line must be blank, i.e. there needs to be a carriage return at the end of this line.

An actual .gwc file could look like the following:

# This is a comment line....not the header line - the next line is

This example file above (10_well_screens.gwc) has 10 well screens in 9 boreholes. Well W-47 has two different screen intervals. Note that line 2 contains the word Elevation and the number 6.0 which is the max-gap parameter. There are 10 rows of data and there is only one analyte value per line, but up to 300 could be included in a single file.

If we view this file using the Map_Spheres module, the resulting output will be:

[10_wells_gwc.jpg]

The application represented by this figure used the Map_Spheres module with the following settings and enhancements:

Rmax was set to 2.0

Under Sphere Connectors, Sample Indicators was None and Sample Connectors was set do Color Tubes.

The datamap was edited. The datamap used is saved as _gwc_normal.dmp. This datamap has a discontinuity at datamin. The two-range datamap is gray at the bottom and immediately changes to a normal blue-to-red datamap.