Backfilling around underground pipe repairs

I have a 100,000 litre free form In ground pool built in 1964. It's shot dyed gunnite and in good condition. At sometime in the past all the underground pipes were re routed from one pump house to another and they all have a street elbow connecting old and new pipes. The connection is made with barbed abs or pvc fittings held in place with stainless steel hose clamps. Last week one of the elbows cracked and water saturated the lawn, eventually bubbling up in a sodden mess. I excavated and about 3 feet down found seven pipes (and 2 electrical conduits) as described above. The cracked fitting was for the spa supply. It's been repaired and now it's time to backfill. All of which leads to my question- the fittings are all the same age, but I don't feel up to replacing them all right now. They are all in good shape and there is no evidence of fatigue. But it was a brutal job excavating the pipes through heavy, dense compacted clay. I ended up with a pressure washer and shop vac making like a vacuum excavator. I would love advice about possible alternatives to backfilling with soil. I wondered about covering the pipes with gravel then landscape cloth with a few inches of top soil to finish so that I could uncover the pipes quickly if I needed to. But I am worried that they will be subject to freezing in the cold Ontario winters. I know they are all blown out at closing but the pipes are old and I think that the spa supply crack might have been caused by water leaking in over the winter. Any advice is much appreciated.
 
Welcome to TFP!

Not sure about the impact of the cold waaayy up there. :) But, I can say for sure that while digging in clay soil is hard work digging in gravel is worse.
 
First -- You should replace all the hose clamps now -- they are well beyond their expected life.

Second: As to filling you should fill with construction sand -- all purpose sand --

Don't use playground sand --

The last 4 to 6 inches should be the original soil.
 
Ditto to the comments about how miserable it is to dig in gravel... :-(

Don't do it.

What volume is the hole you're trying to fill? I wonder if there's some practical lightweight material you could put in there over the winter, so you can work on it next year. Or is this supposed to be a long-term solution, not just to get you through the winter?
 
Thanks for the replies. I was afraid someone was going to suggest that I do all the fittings now. I think in the back of my mind I knew it was the right thing to do but it means spending the afternoon with a heat gun and my head 3 feet down in a muddy hole. But better now than later. I think sand is the way to go. I'll keep you all posted.


Erik
 
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