Looks good, but if I were you I'd form up around the inside of your valve pit and pour an open top concrete box surrounding the valve. You could put a steel or concrete cap on top. That would keep the dirt off your valve and stem, probably at least double the life of the system. But if you did that you'd need to install a pvc drain at the bottom of the box to drain any water which might accumulate inside. Sounds like some expensive repairs on the dozer.
