You have gotten some pretty sage advice. The first item on the list is to convey to management is this type project isn’t cheap.
I would like to add that getting the proper permits and informing everyone can add considerable time and effort to your project. Make sure you inform everyone that has an interest and have every required permit. Watch the dates and times on the permits. We got bit by an expired county permit on a close out job, $350 turned into $5,000 and delayed the project several days.
The permit situation is most critical as about the worst thing that happen your type project is some agency catch you without the proper permits. You will be watched, inspected, and put on tape or memory chip.
Once you scope out the project make sure that it includes a contingency plan for any spills or events that may occur. This plan or ideas should include a worst case scenerio. This type of plan is sometimes required by the agencies, but should be looked at even though not published if not required. This would include things like where is a supply drums, where is a S/S vacuum truck, and others.
I just checked and we had to pay $525 per 55 gal drum 2/3 full. This is plus freight and any special transport required. This was material going to a hazardous waste landfill in another state.
Good Luck