Find a local independent insurance agent who specializes in commercial insurance. You are looking for a general liability policy that does not exclude your operation. There are specialty carriers out there, not terribly expensive, so long as you don't allow broadhead use. Make sure the carrier is at least A- or higher rated from A.M Best, the largest rating service of insurance companies. You should be able to get this coverage as part of your overal business insurance package. You should also consider purchasing an umbrella liability policy