Analyte Time Files Format

Discussion of Analyte Time Files

Analyte time files contain 3-D coordinates (x, y, z) describing the locations of samples and values of one or more analytes or properties taken over a series of different times. Time files must conform to the ASCII formats described below and individual entries (coordinates or measurements) can be delimited by commas, spaces, or tabs. They must have either a .sct (Soil Chemistry Time) or .gwt (Ground Water Time) suffix to be selected in the file browsers of EVS modules. Each line of the file contains the coordinate data for one sampling location, or well screen, and any number of chemistry or property values. There are no limits on the number of borings and/or samples that can be included in these files, except that run times for execution of kriging do increase with a greater number of samples in the file.

Time data can be visualized independently (without geology data) or within a domain bounded by a geologic system. When a geologic domain is utilized for a 3-D visualization, a consistent coordinate system (the same projection and overlapping spatial extents) must be used for both the chemistry and geology. The boring and sample locations in the time files do not have to correspond to those in the geology files, except that only those contained within or proximal to the spatial domain of the geology will be used for the kriging.

If the posting of borings and sample locations are to honor the topography of the site, the chemistry files also must contain the top surface elevation of each boring.

Format:

You may insert comment lines anywhere in Analyte time files. Comments must begin with a ‘#’ character. The line numbers that follow refer to all non-commented lines in the file.

The format of chemistry time files is substantially different from other analyte file formats (.apdv or .aidv) used in EVS. These differences includerequiredanalyte name and unitson line one (no other information allowed), and no need to specify the number of samples or number of analytesandtimes.

Line 1: This line contains the name of each analyte. After every analyte has been listed the analyte units are then required for each analyte. Analyte Units are REQUIRED for time chemistry files.

Line 2: This line contains the mapping of the analytes to a specific date. This is done by listing the analyte name followed by a pipe character “|” and then followed by the sampling date. There should be one of these mappings for every column of data in the file. If you want a space in your analyte name you may enclose the entire name and date in quotation marks (example: “Vinyl Chloride|6/1/2004”). Optionally the analyte name may be omitted and just a date used, in this case the first analyte name listed on line one will be used.

It is required that the order of analyte-date columns be from oldest to newest for each analyte.

The date format is dependent on your REGIONAL SETTINGS on your computer (control panel).

C Tech uses the SHORT DATE and SHORT TIME formats.

If the date/time works in Excel it will likely work in EVS.

For most people in the U.S., this would not be 24 hour clock so you would need:

“m/d/yyyy hh:mm:ss AM” or “m/d/yyyy hh:mm:ss PM”

Also, you MUST put the date/time in quotes if you use more than just date (i.e. if there are spaces in the total date/time).

Line 3: This line must contain the word Elevation or Depth 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; if depths below the top surface elevation are used, then this parameter should be Depth.

FOR GWT FILESONLY:the second parameter in this line is a real number (not an integer) specifying the Max-Gap in the same units as your coordinate data. 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 samplesis equal to theinterval divided by max-gap roundedupto an integer.

The last value on this line should be the units of your coordinates (e.g. feet or meters), or the flag word reproject.

Lines 4+: The lines of sample data:The content of these lines varies whether the files is a SCT or GWT file. GWT files have an additional column of elevation (Z) data to allow for specification of the top and bottom of each screen interval, whereas SCT files specify the location of a POINT sample (requiring only a single elevation).

X, Y, Z (for Chemistry files or Well Screen Top), Well Screen Bottom for groundwater chemistry files) , (one or more) Analyte Value(s) (chemistry or property), Boring name, and Elevation of the Top Of The Boring (optional).

There are several flag words available for missing values these include:

1. unmeasured
2. not-measured
3. nm
4. missing
5. unknown
6. unk
7. na

For non-detect samples the following flag words are available:

1. 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.
2. nondetect or
3. non-detect
4. nd

The boring name cannot contain spaces (recommend underscore “_” instead), unless surrounded by quotation marks (example: “B 1”). The optional boring name and top are needed only by the post_samples module for posting tubes along borehole traces and for generating tubes which start from the ground surface of the borehole. Numbers and names can be separated by one comma and/or any number of spaces or tabs.BLANK ENTRIES (CELLS) ARE NOT ALLOWED.

When Top of Boring elevations are given, they must be provided for all lines of the file.

#Soil Chemistry Time File Example (SCT)

“ethane"“ethylene"“mg/kg"“ug/kg”

“ethane|6/8/1976"“ethylene|6/8/1976"“ethane|1/12/1979” “ethylene|1/12/1979” “ethylene|3/16/1981”

Elevation meters

12008 12431 22.9 22 Unk 21 500 0 CSB-39 30.4

11271 13105 18.9 0 0 0 2800 0 CSB-40 35.9

10652 13857 23.4 0 0 0 290 0 CSB-41 28.1

9904 14522 18.4 0 0 0 Unk Unk CSB-42 22.8

9029 15283 37.9 0 0 0 23 0 CSB-43 30.1

For the GWT file below, those items that are unique to GWT (vs. SCT) are in BLUE.

#Ground WaterChemistry Time File Example (GWT)

“ethane"“ethylene"“mg/kg"“ug/kg”

“ethane|6/8/1976"“ethylene|6/8/1976"“ethane|1/12/1979” “ethylene|1/12/1979” “ethylene|3/16/1981”

Elevation3.0meters

12008 12431 22.9 15.2 22 Unk 21 500 0 CSB-39 30.4

11271 13105 18.9 12.5 0 0 0 2800 0 CSB-40 35.9

10652 13857 23.4 19.0 0 0 0 290 0 CSB-41 28.1

9904 14522 18.4 11.8 0 0 0 Unk Unk CSB-42 22.8

9029 15283 37.9 30.3 0 0 0 23 0 CSB-43 30.1

• Time Domain Analyte Data

  We recommend that analyte files which represent data collected over time use either the APDV or AIDV format and include data for only a single analyte

• Time Domain AIDV Example File

  | x | y | ztop | zbot | @@1/1/2001 | 5/1/2001 | 8/1/2001 | 11/1/2001 | 7/1/2002 | Site ID | Ground | | — | — | — | — | — | — | — | — |

• Legacy Analyte Time Files

  Deprecated The SCT and GWT time file formats are deprecated. It is now recommended to use the APDV or AIDV formats with dates as analyte names to handle time domain data. See Creating Analyte Files Representing Measurements Over Time for details. Overview The SCT and GWT analyte time formats are legacy formats and are no longer recommended for new work. Use APDV or AIDV with dates as analyte names instead — see Creating Analyte Files Representing Measurements Over Time. This page documents the legacy formats for reading and maintaining existing files.