Originally Posted by muddywater
10-4 4" solid cynder blocks as a base will be cheap insurance.
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Maybe. If you can assure their stability. A one piece slab would be my choice.
I am also curious as to how you plan to access the pump when it needs cleaning or replacing without moving the water feature AND how you are allowing for sufficient water flow to the pump intake. This may require drilling holes in this valve box which will weaken its weight bearing capabilities.