Three Dimensional Chemistry File Example

Discussion of Chemistry or Property Files

Chemistry or property files contain horizontal and vertical coordinates, which describe the 3-D locations and values of properties of a system. For simplicity, these files will generally be referred to in this manual as chemistry files, although they can actually contain any scalar property value of interest. Chemistry files must be in ASCII format and can be delimited by commas, spaces, or tabs. They must have a .csv suffix to be selected in the file browsers of EVS modules .The content and format of chemistry files are the same for 3-D modules, posting modules (sphere), and fence diagram modules, except that fence diagram files require special subsetting and ordering. Each line of the chemistry file contains the coordinate data for one sampling location and up to 300 (columns of) chemistry or property values. There are no computational restrictions on the number of borings and/or samples that can be included in a chemistry file, except that run times for execution of kriging do increase with a greater number of samples in the file.

Chemistry data can be visualized independently or within a domain bounded by a geologic system. When a geologic domain is utilized for a 3-D visualization, a consistent coordinate system must be used in both the chemistry and geology files ( i.e., either elevations or depths must be used for the z coordinate in both files). The boring and sample locations in 3-D chemistry files do not have to correspond to those in the geology files, except that they must be contained within the spatial domain of the geology, or they will not be displayed in the visualization. If the posting of borings and sample locations are to honor the topography of a site, the chemistry files also must contain the top surface elevation of the boring. As will be described in later sections, EVS uses tubes to show actual boring locations and depths, and spheres to show actual sample locations in three-space. In order for these entities to be correctly positioned in relation to a variable topography, the top elevation of the boring must be supplied to the program.

Format:

You may insert comment lines in C Tech Chemistry (.csv) 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 must use underscores and EVS will convert underscores to spaces (example: Vinyl_Chloride in a .csv file will be converted to "Vinyl Chloride")... Or you may enclose the entire name in quotation marks (example: "Vinyl Chloride").

A good example of analyte name usage is 5_chemicals.csv in the \ctech\data\chemistry\ directory.

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

• many modules use actual 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_samples’ 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 must contain the word Elevation or Depth (case insensitive) or the numbers 1 or -1 respectively to denote whether sample elevations are true elevation or depth below ground surface. If actual elevations are used (a right-handed coordinate system), then this parameter should be Elevation (1); if depths below the top surface elevation are used, then this parameter should be Depth (-1).

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

Note: The ability to use the words Depth or Elevation 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 samples (rows of data) to follow. The second integer is the number of analyte (chemistry) values per sample.

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

For fence diagrams generated using Krig_Fence (old style), the samples must be sorted such that all samples for a given boring are together and proceed from shallow to deep for each boring. The order of the boring sample groups determines the connectivity of a fence diagram.

Line 4: The first line of sample data. X, Y, Z, (one or more) Analyte Value(s) (chemistry or property), Boring name, and elevation of the top of the boring (optional). The boring name cannot contain spaces (recommend underscore "_" instead), unless surrounded by quotation marks (example: "B 1").

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)

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 .csv file could look like the following:

This file uses z coordinates (versus depth) for all samples, therefore line 2 has the word Elevation. There are 50 samples and 5 analytes (chemicals) per sample.

Another example using depths from the top surface is: