Insurance coverage of improvements with unlicensed team

[Gordon Middleton]

Wasn't sure how to word the title, but here are the details.

I have a contract with a landowner to use his existing dock on a public waterway. The contract entitles me to perform, with approval from the landowner, any improvements needed to use the dock for my purposes. I've come up with a solid plan for the work and have a well-respected, but unlicensed welder to perform the work. He'll bring with him one two day laborers to help with some of the heavy lifting, but mostly will perform the work alone. The owner likes the plan and knows the welder personally, but wants me to bring insurance to cover any liability associated with the work, which I am more than happy to do. 

The issue I'm having though is that I don't own the land, am not leasing the land (dock lease), and am not a general contractor. My property management company's insurance could cover the liability of a handyman, but this beyond hammer and nails. We're talking fairly major equipment. I've asked around, but I'm not exactly sure how to get this covered. Any advice appreciated.