The equipment to be used in the Source Water Assessment and Protection Program will be Trimble Pathfinder Pro-XR GPS / DGPS beacon receivers with real-time differential capability. The Trimble TDC1 datalogger operating Asset Surveyor software will be used to record attribute data information. The field data will be downloaded to Trimble Pathfinder Office Windows-based processing software. A Laser Atlanta ProSurvey 1000 laser rangefinder or equivalent equipment will be used to determine the offset distance and azimuth from the GPS antenna to the point of interest if it is not possible to locate the antenna on or directly adjacent to the point of interest.


It is essential that field personnel be trained in the operation of the above GPS and laser rangefinder equipment to produce consistently accurate (3 to 5 meters) geographic latitude / longitude positions. A qualified GPS instructor or a knowledgeable, professionally trained GPS operator will provide this training. Documentation of all training will be recorded in the project file and detailed in the quarterly project reports.


Run Trimble "Quick Plan" software program to determine the anticipated satellite constellation configuration for the time and area of interest.

Complete the mission checklist (attached) to ensure all necessary equipment is prepared and loaded.

These two steps will assist the field personnel in determining when satellite constellation configuration will be suitable for operations to be performed. (There is typically one to one and a half hours a day when the satellites are out of position; these steps will assist in planning around these times, however, as a safeguard, the equipment can not collect data when these outages occur - see Settings)


Maximum Potential Dilution of Precision (PDOP) is 6.0

Elevation mask is 15 degrees

SNR mask is 4

PDOP switch is 6.0

Dynamics code is "Land"

Position Mode is "Manual 3D"

Logging interval is one (1) second

Minimum positions is thirty (30)

Coordinate system is Latitude / Longitude

Datum is WGS84

Recording in 3D Manual mode

Magnetic North


Local time is UTC -6 for CDST and UTC -5 for CST

RTCM is "On"

Note that in the above settings, the receiver will collect positions only if it is receiving the satellite signal and the Differential Global Positioning System (DGPS) signal simultaneously, ensuring that all data logged is usable.


With the equipment operating, PDOP value under 6 and receiving the DGPS signal, (equipment will not log data unless these conditions exist), use the data dictionary designed for the project (design is presently in draft form) to input attribute data while the minimum number of positions (30) are being collected. The antenna should be located as near as physically and safely possible to the point of interest. The laser rangefinder will be used to determine the offset distance and azimuth from the GPS antenna to the point of interest if it is not possible to locate the antenna on or directly adjacent to the point of interest. These data will be entered into the datalogger and transferred to the Microsoft Access data collection program.

Data Quality Assurance

For each day of field operations, the first position collected by each receiver will be duplicated. A set of thirty positions will be collected and the average position will be set and Waypoint #1 utilizing the navigation feature of the GPS receiver. Without moving the antenna, a second set of thirty positions will be recorded and the average position will be set as Waypoint #2. The "MEASURE" function of the GPS datalogger will be used to measure the distance between the two waypoints. In order for GPS operations to continue for that day, the average positions will have to agree within 3 meters. The positions of the two waypoints and the measured difference between them will be permanently recorded in a data quality field book. A copy of the daily GPS .ssf file will be forwarded to DEQ headquarters to a person to be designated who will evaluate these files for compliance with the QA /QC protocol and for archiving.

If the two waypoints are within 3 meters of each other, operations will be allowed to continue that day. If it does not, the antenna will be moved to a new location and the test will be repeated twice. If the two additional tests both provide results within the acceptable variance, GPS operations will be allowed to proceed for that day. If the two additional tests do not both provide results within the acceptable variance, GPS operations will cease and the equipment will be returned to an authorized service center for evaluation.


At the end of each day of GPS operations, the data will be downloaded to the Pathfinder Office software for processing into the Geographic Information System (GIS). The data will be backed up daily on 3.5" diskettes. After successful incorporation of new data into the SWAP GIS, the data will exist in the GIS, with backups in the Pathfinder Office software and on 3.5" diskette.




____ Receiver 

____ Batteries / Power Cord

____ Antenna and Magnetic Mount / Tripod

____ Antenna Cable 

____ Datalogger

____ Spare Datalogger Batteries

____ Laser rangefinder w/ charged battery


  1. PRESS "Func" key, then press "Config" key

  2. Press "Enter" key twice to check "Rover Options":

  • Logging intervals

    • Point feature 1s (one second)

    • Line/Area 10s

    • Not in feature None

    • Velocity None

  • Minimum posns 30

  • Carrier phase

    • Minimum time 10 mins

  • Pos mode Manual 3D

  • Elev. Mask 15 Degrees

  • SNR Mask 4.0

  • PDOP mask 6.0

  • PDOP switch 6.0

  • Audible click Yes

  • Log DOP data No

  • Dynamics code Land

  1. Press RTCM (Function 1) key

  • RTCM input mode On

  • RTCM version Auto

  • RTCM station Any

  • Warning time 20s

  • Log PP data No

  • Baud rate 9600

  • Data bits 8

  • Stop bits 1

  • Parity None


  1. Connect cable to antenna

  2. Connect Datalogger to cable

  3. Connect power (batteries or cig. lighter cord)

  4. When in position to collect data, push "On"

  5. Wait for machine to initialize (PDOP <6, R)

  6. Scroll up to "Data capture", press "Enter"

  7. Select either "Create rover file" or "Reopen rover file", press Enter after your choice is highlighted

  8. To create rover file:

    1. Type in file name

    2. Highlight and select data dictionary

    3. Press "OK"

  1. To reopen rover file, highlight this option and press "Enter"

  2. When ready to collect data, press "Enter".

  3. After all required data is recorded and when a minimum of 30 positions have been collected, press "OK"

  4. Continue to next Potential Source of Contamination or Well and repeat steps 9 and 10 above.


Louisiana Department of Environmental Quality 602 N. Fifth Street Baton Rouge, LA 70802
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