New Foundation Excavation - Found Old Septic Tank

Contractor just broke ground last Friday, found the old septic tank original from 1952 when the home was built. City sewers came eight years later in 1960 so the septic tank has not seen anything new since that time. Uncovered it and it was full of water, excavator had it pumped out and broke up the upper part of the chamber, left the rest alone below where the new footing will go. Contractor was going to fill it with rock and concrete, maybe some rebar.
Town engineer came by on Monday and failed the excavation, wants contractor to make sure the load bearing capacity of the soil underneeth the old septic pit meets the minimum in our area, NJ all clay two feet below grade, I think it needs to be 2500 lbs per sq ft. So we have a soil engineer coming to test it.
Does anyone have any thoughts on this they can share with me? Not familiar with the engineering involved in a foundation for a new home, not like we're building a wal-mart or something. Obviously I don't want it to shift ever, either.
Thanks!
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snipped-for-privacy@optonline.net says...

I know when a new footer was poured for my house (foundation repair), it had to go to undisturbed ground. You don't want anything that may compact or settle further; you want the foundation to rest on ground that's been there forever. So, yeah, the engineer failed it. Go with the stringent requirements of the town engineer.
Banty
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says...

Agreed, you need to dig down to below the old septic tank to solid undisturbed soil the same as the rest of the foundation. The inspector may allow you to step the footing down the extra deep portion of the excavation or he may want you to pour the footing full depth from the bottom up to level with the rest of the house footings. I would at least run two rows of 1/2 or 5/8 rebar along the entire footing and cross the old septic tank hole without any joints in the rebar, plus maybe add an extra rod in that area.
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On Jul 20, 11:16 am, snipped-for-privacy@optonline.net wrote:

Engineer could design a grade beam to span the questioned area. He will balance cost of alternative solutions. T
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snipped-for-privacy@optonline.net wrote:

Insane, absolutely insane.
The sub-surface damn sure supported a tank full of liquid for fifty years, didn't it?
And what's the worst that could happen? YOUR deck/floor/driveway leans!
Asses, you ask me.
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might be a cavatity under that tank. do it right and do it once.
cost to do it right now, low.
fix it later very pricey
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snipped-for-privacy@aol.com says...

Yeah - can't imagine anyone sane wanting to cut corners or guess around on this one...
Banty
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On Fri, 20 Jul 2007 08:16:43 -0700, snipped-for-privacy@optonline.net

Usually you have to break the bottom of the tank so that it will not hold water ever again. Then to abandon the tank it is usually filled with sand or small gravel that won't settle over time.
But you want to build a footing in that spot...

Yup. Listen to the town engineer or hire your own engineer (not building contractor) to design the proper footings.
sdb
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On Jul 20, 11:16 am, snipped-for-privacy@optonline.net wrote:

My father regreted busting up and filling in his tank. He now wishes he could have used it to store rainwater for his garden.
R
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