I'd say your both low. But again I'd need a lot more info.
My view is this: Im going to assume you'll need mini excavator and Hydro-vac in some cases depending on markouts.
Plus you will need min. 2 people just for safety
Mini Excavator with operator is $150 MINIMUM per hour ground hand $75 per hour so thats $225 an hour MINIMUM
and before anyone gets excited take that $75 and deduct the cost of your libilaty insurance, Workers Comp. state and federal taxes and social security ETC. now that number don't look so good. So yes $75 for ground hand.
Now if you have to use Hydro-vac for exposing other utility's it's even more costly. Plus now add the cost of the gravel base and your getting closer to the true cost.
Thats at just the Minimum or why bother taking your equipment off the lot. None of these guys work for free and neither should you.