Driving over a septic tank

[crazyjake8493]

When I bought my property I did not know where my septic tank was. I used my tractor and a couple times a concrete delivery truck run over it( i found it later) no damage was done. I still run over it with my tractor when I bring cages loaded with firewood. It is a 50-60 year old concrete tank

Similar situation here. When I bought the house I was told where the septic tank was. Cut down a big tree and a buddy came over with his pickup to cut it up and haul it out for firewood. A few years later I had the tank pumped and it turns out the tank was 10ft off from where I was told. His firewood-loaded pickup truck was parked right on one corner of the tank.

No damage to the tank. It's also a 50+ year old concrete tank. The top of the tank is also about 42" below grade.

I drive over it every week with our riding mower, but I avoid it with the tractor and anything else just to be safe.

 

[crazyjake8493]

I have an LS 4140 with cab and loaded tires. Estimated weight is 5500 lbs.

Would it be safe to drive over a septic tank buried 10” below grade?

That's really shallow for the top of the tank. I'd be nervous about anything on it at that level, especially a big tractor. Our tank is roughly 42" below grade and I've never seen any here less than 30" below.

 

[paulsharvey]

Tank itself will likely be fine, but there really isn't a good reason to try it. You just never know if the lid was cracked when placed, and just mudded up, maybe it's very old, maybe it's a new poly tank, with a poly riser and poly lid. Heck, I've seen ones so old they had no bottom, 3 coarses of CMU, and planks over the top.

10-12" of soil does distribute the weight a pretty good bit; but its still not smart. Guys talking about 30+ inches of coverage; you would be fine.

Drain field; 4" poly perf pipe in a sock of Styrofoam peanuts, at 6" deep; that's where I would be most concerned.

So, given OPs situation; would I cross it once to get to the otherside, to do a specific one time task, yeah; would I mow over it every weekend, no.

If you really Must cross it, maybe consider additional protective measures; like poly pallets, mounting sand on top, or similar.

 

[aircommuter]

Picture of a tank lid I made on the job.

 

[paulsharvey]

I like the manhole lids, But, you have those ram neck sealed, grouted, or do those have a air tight gasket?

 

[aircommuter]

I like the manhole lids, But, you have those ram neck sealed, grouted, or do those have a air tight gasket?

The concrete rings are ram neck sealed and the lids are “O”ring with bolts. They are gas tight lids.

 

[Gord Baker]

Picture of a tank lid I made on the job.

The new top is very nice. It would unlikely hold a 40HP Tractor or Pickup
They are 3-4' deep in Ontario due to frost. Neighbours tank filled and Froze one year. NOW you have a problem!
Your cover is a Foot or so and offers no real strength or support. Riding lawnmowers should be safe, but more than one person has died from going through the top of a Septic Tank.
I cut plastic Barrels off to cover the 'manways' for pumpouts. Then I only have to dig a foot or so, then pull the barrels (S.S. U bolts) to access the hatches.
They make a plastic T fitting that can be pushed in a 3 or 4" Outlet tile. This keeps floaters from going out into the Weeping bed. Highly recommended.

 

[aircommuter]

The new top is very nice. It would unlikely hold a 40HP Tractor or Pickup
They are 3-4' deep in Ontario due to frost. Neighbours tank filled and Froze one year. NOW you have a problem!
Your cover is a Foot or so and offers no real strength or support. Riding lawnmowers should be safe, but more than one person has died from going through the top of a Septic Tank.
I cut plastic Barrels off to cover the 'manways' for pumpouts. Then I only have to dig a foot or so, then pull the barrels (S.S. U bolts) to access the hatches.
They make a plastic T fitting that can be pushed in a 3 or 4" Outlet tile. This keeps floaters from going out into the Weeping bed. Highly recommended.

Tank covers must be accessible at ground level due to local code. The lid is 6” thick with #6 rebar on 12” centers and # 4 rebar on 6” centers. The tank was existing about 20’ from the garage. They have been driving over it for 20 years. I am a general engineering contractor since 1980. I haven’t done little jobs like that since the mid 80s. That was just helping my neighbor. Oh yes those T fitting outlets are standard code also for at least the last 50 years around here.

 

[paulsharvey]

Ok, so Not taking into account for the dirt on top; the lid as described; Should have a service load of about 1850#/sq ft, or a single point load of about 5900# at the center. Now, yes, using Chat do to the calcs, as i haven't ran beam loads in like 19 years... So, even buried 12" it seems to all into the "probably shouldn't dry over it with propane delivery truck", but you pull a passenger car over it, you are fine, As Long as there are no hidden defects, which can happen on an old lid. Minor curing cracks can allow gasses to attack the steel, and our whole thing changes.

Basically, with 2:1 soil transfers, this lid should still take an 8000# load. With a 1:1 soil transfers to the lid, 5000# single point load starts getting a bit iffy.

Again, goes back to, probably shouldnt, but if its a couple times, and you're that worried, use something to spread point loads

 

[paulsharvey]

Tank covers must be accessible at ground level due to local code. The lid is 6” thick with #6 rebar on 12” centers and # 4 rebar on 6” centers. The tank was existing about 20’ from the garage. They have been driving over it for 20 years. I am a general engineering contractor since 1980. I haven’t done little jobs like that since the mid 80s. That was just helping my neighbor. Oh yes those T fitting outlets are standard code also for at least the last 50 years around here.

Ok, I miss read that, and ran with #5 bars long ways, and the #4 bars transverse; so I under sold your lid by probably a factor of 3...