If you can find someone on CraigsList or similar in your area that sells used commercial swimming pool covers, they are great, both as tarps and ground cover. Most commercial pools are required to replace their pool covers long before the material goes bad from the UV and chlorine. Around here in Sac, they are available cheap, are huge, and can be cut into whatever size you need. They are extremely thick and strong, since they are required to take the weight of someone on them while covering a pool... not like a tarp. I lay a piece of that down, or whatever else would be going to the dump that would work as ground cover, and then a pallet on top to hold the piece of equipment. The pallet protects whatever you are using for the actual ground cover, even heavy-mil black plastic, plus lifts the equipment off the ground. If you have a forklift, then also easy to move it around on the pallet. Sometimes you can find an above-ground pool for free to haul away, and that heavy vinyl can be cut into useful pieces. Even old carpet works for two or three years.