<human>: About 7 years ago we bought a small home on about an acre of land. The purchase went as normal as expected. The lot next to our home is empty and after moving in we walked its perimeter out of curiosity. At the far side of the lot we discovered signs marking gas pipelines owned by a large well known company. After a bit of research we discovered that these pipelines run through our lot. 

We were not aware of this when looking at the home, no one brought it up, and nothing was mentioned in the paperwork that there is an easement that runs across the yard.

Since moving in we have built a 10x12 shed in the back yard. While building the shed an individual who works for said gas company stopped by one day and said we could not build there due to the easement. We asked for evidence (paperwork, a contract, anything) stating there was an easement and that we could not build. Nothing was received and the structure was complete.

Fast forward to last week, I come home from work and notice a small white flag in my back yard from the gas company. They were surveying the land for possible excavation. We called the number on the flag and discovered that the gas company believes they will have to dig in my back yard to repair an issue with the pipeline. This has the potential of not only disrupting my lawn :) but also may require disruption of the shed we have build. I'm worried that they'll have to have it moved (not an easy feat) or they'll destroy it. More importantly, we were not aware and have not signed any agreement with the gas company regarding this easement.

What should I do in this case? No action has taken place yet. We just found out about this after calling them. They said they'd contact us, but didn't initially. I'm worried I'll come home and find a giant trench and rubble with no recourse. 

I would appreciate any advice.

Can you give me a shortened version of the text?
<bot>: We bought a house 7 years ago, found out it has a pipeline running through the yard, now the gas company wants to dig. Help.