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Septic tank covers, openings & access ports:
What are the types of septic tank covers, how do we assure the septic tank (cesspool, drywell, or seepage pit) cover is safe;
How deep is a septic tank cover buried, & do we find & remove septic tank covers?
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SEPTIC TANK COVERS - Once the Septic Tank has Been Located How Deep is The Septic Tank Cover & Is the Cover Safe?
Tank Cover Depth: How deep will the septic tank cover be?
The top of the septic tank is often about one foot below the surface. But this depth varies alot.
However the septic cover can be several feet deeper. If you note the depth at which the waste line leaves the building foundation wall, say perhaps 3 ft. below the top of soil (grade level) then if the site were dead flat and if the tank were
Found 12 feet from the foundation wall, at a typical waste line slope of 1/8" to 1/4" per linear foot of run, the septic tank's entry port for the waste line would have to be roughly 3 ft. 3" below grade level.
Obviously if the site is not flat these septic tank cover depth estimate numbers change.
Be absolutely certain that the covers and cleanout access covers over the septic tank are secure and durable so that it will be impossible for someone to fall into the tank (which is often fatal), and so that a child could not remove the cover.
If your septic tank is in an area where vehicles may drive over it, special heavy-duty rated covers are available. Discuss this option with your septic tank contractor.
If there is the slightest doubt about the condition of the septic tank cover (such as seeing subsidence over the tank location) you should rope off the area and prevent anyone from walking over it, again because falling into a septic tank is likely to be fatal.
Reader Question: septic tank cover collapse
11/28/2014 Scott C. said:
I have a septic system with a power assited pump tank. The lid collapsed under the weight of the soil it was buried under. There was about 3'2" of clay type soil that the installer covered it with. The lid thickness is 4". Is that up to standard for that much soil? - [This question was originally posted at SEPTIC TANK DEPTH]
If you want to investigate the adequacy of the lid over a septic tank you need a bit of data. Septic tanks are indeed rated for different weights and loads.
The thickness of the septic tank lid alone is not enough to know whether or not it was adequate - as we don't know if it contained steel reinforcement or if it did, on what spacing and using what material, nor do we know the quality of the concrete, nor its history (e.g. prior vehicle traffic over the tank) nor do we know the septic tank and size.
Continue reading at SEPTIC TANK OPEN, HOW TO or select a topic from the More Reading links shown below.
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Frequently Asked Questions (FAQs)
Question: how to reduce septic tank opening to install riser and lid
(Oct 28, 2014) deb said:
i have a concrete septic tank built in 1960. Mandatory municipal inspection are requesting a new lid. presently the openof the is 2 feet by 4 feet and covered by a huge slab of flagstone. im not sure how to reconfigure the opening to make it smaller so that i can install a poly lid and possibly a riser
I agree that a 4-foot septic tank opening dimension is probably larger than needed.
Deb: you'd need to overlay and seal to the existing septic tank top a pre-cast concrete slab, reinforced and of same thickness as the septic tank lid, leaving a standard septic tank access opening size over which you can install a riser and new lid. Be sure that the new septic tank lid is child safe as well as of adequate strength to avoid collapse hazards which can be quite dangerous.
Before doing anything, I'd ask an experienced septic installer to inspect the tank for safety and adequacy as the odd sized opening might indicate some home made and possibliy unsafe system,.
Question: report of septic tank lid collapse
2 Jan 2015 Anonymous said:
I purchased my home 15 years ago. The previous owner connected to a sanitary sewer system when it became available bypassing the septic tank. I heard a loud thump recently and upon investigation found a rectangular hole 2 feet by 3 feet and about 5 feet deep. It is in the general location of where the septic tank should have been . Could the old tank lid have collapsed?i If so, can I just cover up the hole? There seems to be only water in the hole. No sewage or effluvia is present
Watch out: indeed this sounds like a dangerous septic tank collapse - which can be fatal if someone falls into the septic tank. It also sounds as if the tank was not properly abandoned - by emptying, cleaning, and filling with sand or other suitable material.
Properly a tank is abandoned following procedures at SEPTIC TANK ABANDONMENT GUIDE
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