Tagging Locations With a Handheld GPS

Occasionally a landfill will encounter a situation where it becomes necessary to pinpoint the location of a specific load of waste. Probably the most dramatic example of this is trying to find evidence for a crime: a weapon or body.

However, for every front-page example, there are perhaps hundreds of other, everyday situations where such information would be useful—perhaps even vital. One of the most common is in regard to placement of vertical extraction wells for landfill gas (LFG).

When installing vertical LFG wells, there are certain wastes that the driller would like to avoid, such as concentrated areas of concrete rubble, metal, tires, or other materials that are difficult to penetrate or may damage the rig.

Also, many landfills accept asbestos, dead animals, various types of sludge, and other wastes that may pose increased risk or operational problems if exposed.

A small number of landfills use differential GPS on the landfill machines to tag these types of loads. However, equipping even one landfill machine with differential GPS can be very costly…we’re talking six digits.

This is, of course, because of the sophisticated equipment needed to provide centimeter-level accuracy. Such systems provide very valuable data, including location tagging (waypoints), constantly updated topographic mapping, transfer of real-time survey control from the office to the field, proximity warning, and a host of other very useful, but fairly expensive tools.

So what if you just want to periodically tag the location of a specific load of waste? Along that line, I was recently contacted by someone who wanted to mark the location of loads of asbestos as they were dumped into the landfill. Can this be done effectively and cost-effectively?  The answer is, “Yes.”

There are various types of handheld GPS units available. These are similar to the units commonly used in automobiles. However, some are geared more toward field application. One of the newest and most effective models is the Oregon 550t, made by Garmin LTD.

ith a list price of $599, this isn’t the cheapest handheld GPS you can buy, but it has what you need when it comes to tagging loads.
This particular unit has lots of bells and whistles, such as a touch-screen display, but most important, it has a built-in 3.2 megapixel camera…and every photograph is accompanied by its own GPS waypoint. These photographic waypoints, logged as lat/long/elevation, can be wirelessly transferred to a PC and converted to a specific layer on your landfill’s CAD drawing.

With the ability to mark specific loads to an accuracy of plus or minus 15 feet, a unit like this could be the next tool you need. One procedure might be to photograph the load manifest, or the load itself, at the dump location. Remember, the goal is to record the location of the load. So, if it’s not practical to stand directly over the location, you should standardize the procedure …maybe stand 20 feet to the north of every load. By establishing a standard offset, your engineer could easily shift the waypoints so they mark the actual location of the load.