During finding & repairing a natural gas leak last week, I discovered erosion under the pool deck near where the gas line ran. The pool is an in-ground poured concrete/gunite pool. The pool deck is concrete about 4″ thick and 3 feet wide.
I have been debating what the correct proportions & make up of the fill should be. The erosion is shown on the picture below. There is dirt & rocks that can be seen, but I’m wondering if I should make the fill 2 parts of dirt, gravel? The decking is going to be replaced because what is there is 5/4 deck boards that have sagged in the almost 40 years they have been there. Redoing the deck will include replacing the 2×4 deck “beams” with at least 2×6’s and taking the time to pour proper footings for them. There were no footings previously, only about a gallon of concrete poured around the bottom of the 2x’s that supported the “beams”. The replacement deck boards will be 6/4 to reduce or eliminate future sag.
So what is recommended for a proper fill? 2 parts dirt & 1 part gravel? or 3 to 1? Or is it better to put a 4 ” gravel layer as a bed for the new footings and then dirt from there & up? As you can tell, I don’t know fill from shinola, and your expert opions are requested.