I live in South Carolina so I am not concerned with the ground freezing. The type of equip I am referring to is a 1988 Dodge Dakota, which I backup the side yard to unload mulch, etc. Next week we will be laying sod and I am concerned with the weight of the the pallets and forklift. The drainline leads from the downspouts at the back of the house, along either side of the house and to with 5' of the street. The pipe is laying directly on the soil, no stone/gravel. There is more than sufficient slope leading from the backyard to the front yard on both sides to accommodate a 12" ditch. We met the contractor at a Home Show, where he stated he installs the pipe 18" deep. But there is no reference in the contract to the depth. What do you recommend?