Collapsing building © Daniel FriedmanSeptic Tank Risers
Definition, Need, & Installation of septic tank access ports

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Septic tank risers or access covers for deep septic tanks:

This article defines septic tank riser and explains how these components are installed to provide adequate cleaning & inspection access openings to pump & maintain a septic tank, cesspool, drywell, soakpit or similar wastewater disposal system.

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Septic Tank Risers: What if the septic tank is buried deep below ground surface?

Septic tank riser & cover, Seal Isle City NJ Tanner & Chase Gilligam (C) Daniel FriedmanReader question: I was told my septic system needs a riser. What's that?

(May 14, 2011) Charles said:

I was told that my septic system needs a riser. What is that and what does it look like?

[Click to enlarge any image]

Reply: definition & description of septic tank riser

A septic tank riser is simply a large diameter round pipe, typically a couple of feet across, that is placed over the septic tank cleanout opening to extend that opening up to close to the ground surface so that the septic pumping company does not have to dig deep into the soil in order to reach the septic tank cleanout cover for pumping and cleaning the tank.

Watch out: just as a septic tank must have a save and secure and childproof cover, so must a septic tank riser, cesspool, drywell, etc. Boys will be boys, as my grandsons demonstrate, standing atop a septic tank riser cover in Seal Isle City, New Jersey. The Gilligan boys provide ample testing of the security and curiosity-proofing necessary at site hazards including septic tanks.

Shown below: an easy-to-access septic tank riser at a property we inspected in Norway. [Click to enlarge any image]

Septic tank access riser at a Norwegian property (C) Daniel Friedman inspected in 2008

Indeed we've seen septic tanks partially above ground, and others buried more than six feet deep. It's not necessarily a mistake, and deep septic components may be required by site conditions, but here are some considerations when the septic tank is more than a foot below ground surface:

Deep septic tanks should have a service riser installed. Septic risers are large-diameter "wells" that are placed over a septic tank inlet baffle access port (and possibly outlet) to permit easy access for septic tank pumping, inspection, and baffle repair.

Steps in Adding a Septic Tank Riser

To add a septic tank riser we

Watch out: Deep drainfields mean poor septic effluent processing. If a deep septic tank means that the absorption area (leach field or drainfield are synonyms) is deep, such that the top of the soil trenches are more than a foot below ground surface, then the reduction in aerobic bacteria in the soil will limit the effectiveness of the drainfield in reducing pathogens and other environmental contaminants.

Additional septic effluent treatment methods can correct these conditions, but it's useful to keep in mind that there is a difference between successful septic effluent disposal and successful septic effluent treatment. A deep septic tank does not necessarily mean that the absorption area is also deep, since site conditions and use of septic effluent pumps may change the required depth of a drainfield.

Safety warning: Be sure that the septic tank riser and all septic tank covers are sound and secure since falling into a septic tank can be fatal. See SEPTIC & CESSPOOL SAFETY .

The two septic tank access risers shown below are dangerous and could easily involve a fatality. At below left is a collapsing home made septic tank made of concrete blocks over which someone placed a concrete cover and slabs of slate to try to cover this dangerous hazard - an inadequate response.

At below right was a two-concrete-block high septic tank riser provided at a mobile home park in New York. The site manager had simply left the septic tank cover off.

Unsafe septic tank cover discovered by simple exploration - we roped this area off and placed heavy plywood over the opening - it was by a children's play area. Unsafe septic tank cover discovered by simple exploration - we roped this area off and placed heavy plywood over the opening - it was by a children's play area.


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