septic riser - drilling into tank for baseplate/adaptor ring?

[WIHD]

Looking to install a septic riser. Issue is one has to 'drill' into the top of the tank to install the concrete anchor bolts which hold the adaptor ring (see pic)

Our septic is prob 40 years old, we are concerned about drilling into the top of of the tank to install these bolts.

Don't want to drill then have the tank crack or something God awful.....any insight here? Is this something I should be concerned about?

Thanks for any input. Calling the company and asking about this was of no help.
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[OccupantRJ]

I would be hesitant also. I saw a service guy poke a locator rod clean through a concrete distribution box that had all but dissolved. Could the top of the tank be pressure washed, allowed to dry, then the ring bonded in place with plenty of suitable construction adhesive?

 

[manwithtools]

Yep, just bond it to the tank with adhesive. The surrounding soil once backfilled will keep it from moving laterally. Proper adhesive or mastic should keep it from floating.

 

[dcg9381]

Looking to install a septic riser. Issue is one has to 'drill' into the top of the tank to install the concrete anchor bolts which hold the adaptor ring

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What's the existing access port? Even the old *** systems I see usually have a > 24" access port.. I'd build a riser there (maybe pour my own concrete) - or build it out of steel. I'd hesitate to drill the existing tank too, let along cut a 24" hole.

 

[no704]

5200?

 

[PCustoms]

If you're worried about drilling the top then shouldn't you be looking at fixing the tank?

I'd drill it all day

 

[jack stand]

I agree with the backfill keeping it in place just fine in the yard or most situations.
Heck I built my riser out of PT lumber (12" +/-) and none of my mowers have ever caused it to move around.
At our previous house I used a cast manhole and riser and it never was attached in any manner. Just the backfill.
This timeline is 30 years between the 2 and is all the proof I need.

 

[mike93lx]

I'd use glue as well, but the tank should be strong enough for a couple tapcons.

I had a tank fail a couple years ago. The inspector easily pushed a probing rod right through the top. No issues with screwing a riser to the new $10k poly tank

 

[PCustoms]

No issues with screwing a riser to the new $10k poly tank

Damn, you could have bought the tank, a mini ex and plenty of beverages to diy at that price!

https://www.homedepot.com/p/VPC-1500-Gal-Yellow-Polyethylene-Two-Compartment-Septic-Tank-87-41760/328984559