The search warrant executed by the USEPA CID may authorize the taking of samples. When this occurs, always ask for split samples. Agents may or may not be willing to provide split samples and you should know that the current practice of the USEPA CID is to not provide split samples, even when asked. And the USEPA CID agents will not be the ones taking the samples. While they may have been trained to do so, the agent will usually leave the sampling to a trained technician.
So what do you do after you ask for split samples and the request is summarily dismissed? Watch what the agents and the technicians do, take careful notes about the sample location and how the sample was collected by either the agent or the technician, the type of testing that will be conducted (i.e. what USEPA method of analysis) and then attempt to replicate the samples. Also, videotape and/or photograph the sample site and the sampling event. If the agent/technician objects, document the objection. Quite simply, if you are not in the way and not obstructing the agent/technician, you are well within your rights to make the videotape and/or take photographs.
Even if you have someone on staff that has been trained to take samples, it is a better practice to retain an outside consultant to take the samples. Have your counsel retain the consultant to take similar samples from the same locations and have the same analysis run on the samples (you have counsel retain the consultant to maintain privileges).
If you wait until after the indictment to ask for split samples, the samples will more than likely be useless (although depending upon the type of material being sampled and the sample analysis method, there may be a spoliation/destruction of evidence claim to be made).
As always, feel free to contact me at firstname.lastname@example.org