I doubt insurance will cover anything beyond damage from raw sewage clean up and damage in basement clean up flooring, drywall, furniture, mold remediation. you have a dedutable, nothing wrong with calling agent and inquiring but my guess is nada.
1800 is a lot of money yes! not nessesarily over priced though A plumbing service company thats all "Legit" ( legit term used loosely) fancy trucks, uniforms, advertizing, fully insured ,bonded , workers comp. probebly be around 200 to 350 an hour on flat rate work , or however much they can get he is going to spend better part of a day out there thats around a couple thousand bucks. I live near (60 miles out ) Los Angeles the closer to the big city higher the prices.
Pktask take a few more pic and share the process hand digging , men on job, hours spent depth of trench. helpful info thanks!