Local Enforcement Agency Correspondence

Guidance in Setting Up GPS Units and Map Datum Selection

Date: September 4, 2003

To: All Local Enforcement Agencies

This all LEA e-mail was sent on behalf of the LEA Support Services Branch and the Facilities Operations Branch of the California Integrated Waste Management Board (CIWMB).

There has been a long series of questions as to how to setup GPS units for obtaining Latitude and Longitude readings for Solid Waste Facilities Sites and Operations as well as Tire Facilities and Locations for use in the SWIS Database. To meet the needs of our WebPages users (and Data base users) throughout the state and world, accurate Latitude and Longitude information is extremely important.

Where to Take GPS Readings:

1. Disposal Sites (landfills, CIA sites, burn dumps, tire piles, etc.): the GPS reading should be taken in the center (centroid) of the waste footprint.
2. All other Solid Waste Facilities and Operations (transfer stations, composting, CD/I, etc.) and Tire Facilities: the GPS reading should be taken at the gate or office.
3. Calibration and Datum selection: When you replace batteries or setup the GPS for use, you should set the GPS with the proper datum (map projection type). The default nation wide is WGS 84 (World Goedetic System of 1984). If this datum option is not available on your GPS unit, then the next best option is NAD 83. Please make sure that the GPS unit is routinely calibrated and the time and datum are correct and please set your GPS readout for Decimal Degrees -or- Degrees, Minutes and Seconds format.

New map features will be added to the SWIS web pages (Facility/Site Summary Detail Reports) in the near future.

If you have questions please contact Skip Amerine at (916) 341-6322.

Thank you,
Melissa Hoover-Hartwick
LEA Support Services
(916) 341-6813

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