I am in the process of designing/pricing out a job where I know we will need 2 1000 gal seepage tanks. I never installed them before. The tank company told em I need 2' of stone all around the tanks. Do I also need 2' of stone under the tanks also? Once we finsh the plan it gets stamped by a engineer and he draws all the details in. I am just trying to get the pricing close, so the client can see where the plan is at before we finish it.