Help! New Gunite Pool Has A "cold Joint" In Bottom.

[poolprob]

Hello,

I am having a 20x40 gunite installed. They "shot" it last week on the hottest day of the year. They started shooting the deep end walls at 7 am, around 2:30 they ran short of shotcrete mix and called for a final 4 yards, it took a couple of hours for the final concrete truck to come, and I noticed that as they trialed the bottom of the deep end, the guys boots were only sinking 3", this was at 5:30 pm, basically in the deep end area where the end of the job meets where they started. PB said dont worry, but I ended up with my boots on in the hole. I stuck the area of concern with a stick, yep, 3-4" wet. My PB got in with a shovel and started digging down, we hit hard concrete. I can measure at the hole for the hydrostatic valve and tell I have about 11" of in the bottom. Earlier in the the "pour", we had a deep end wall slide out and lay a lot of concrete in the bottom, that helped facilitate the problem, because the concrete that ended up in the bottom earlier in the day, is what set up. I know I have a cold joint at about 3.5" down, on top of another 7-8" of bonded concrete, in the very bottom of the deep end. Whether it all bonded I dont know. Very concerned about moving forward without being sure this wont be a problem in the future. I have the concrete supplier coming to look and give opinion, but from talking to them, they can only offer an opinion, and I am sure it will be conservative. Who else can I contact that could do some testing to make sure I wont be in for trouble down the road? What should I do? I really need to be sure before moving forward. Thanks in advance!