Can you be a bit more specific? Clearly no one should be allowed to operate a Moisture/Density gauge until they have been properly trained and are throughly familiar with the instrument. They should be aware of how the gauge operates and how to minimize their exposure to the radiation sources. Troxler has some good, if somewhat sketchy, manuals. The Troxler will be of little use unless you have a good Proctor value for the material being tested.
I worked for a company in the 1980's and no matter what field work you were going to do, you got certified for it. We won a landfill liner bid - so my company said we are going to use a troxler - who wants to take the course and get certified. Ask Troxler - I am sure they can offer some insight. I dont think you can use or even tranport the unit without being certified..I know when techs show up with such units on a job, the unit is chained with a lock to the vehicle so it cant go flying off or get stolen. Best wishes with that.
Troxler has plenty of information regarding the safety and accuracy of their instruments. Also, the Nuclear Regulatory Commission (NRC) has guidance for use of portable gauges in NUREG-1556, Vol 1, Rev 1. This NRC document is available on the internet and it is the laymans explanation of the regulations. In my opinion, it is a very easy read
The information you probably will not find are the fine details of operating the gauge, like "When do you use trench offset?", etc.
I was trained on the use of a Troxler gauge in the mid '80's.
It really isn't rocket science. There are two seperate radiation sources. One in the tip which can be extended into the ground. This sources measures total density. The other source is in the body which measures moisture. Both recivers are in the body. To test an area, a pin is driven slightly past the depth to be tested. The pin is removed and the tip is inserted to the depth to be tested. The average total density between the tip and the body is measured. The Moisture in only the top 2-3 inches is measured (the depth of measurement of the moisture is affected by the amount of moisture.) The macines then computes the effecitve density from the total density and the moisture content. The machine can compute total density in what is called the back scatter mode. In this mode the tip does not extnd out side the body of the machine. The total density is based on reflected radiation and only measures a few inches of depth. This mode is used for paving, but is not verry accurate for earthwork. yet, because it is easier and faster, I have seen it done more than once on earthwork jobs. Other factors that can affect accuracy is the side walls of a trench or certian soil types can in rare instances cause inaccurate readings.
Although you do need a one day training class to be certified to operate a Troxler gauge, you don't need to attend a class to understand how it operates and how to interpret the results. Troxler should be able to get you literature on this or it may even be available on the web. (I didn't look)
Good Luck!
Nukes measure wet density, moisture content, then calculate dry density. If you add a proctor test into the machine it can provide you percent compaction. Nukes do have error in measurement caused by soil minerals and site conditions. In a lot of landfill QA work I have done we have compared many nuke moisture readings to lab tests performed on soil samples removed from beneath the meter. After about 20 comparisons you get a good picture of how much correction is necessary for the soil you're working with. The meter can is often off on moisture content by as much as 3%, and sometimes 7%. This MC error results in bogus dry density calculation. I seen the error topic in instruction manuals by Troxler. Check yours.
