Match The Correct Riser And Lid To The Tank To Ensure Safety And Improved Access For Maintenance

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We are always receiving questions about installing risers and, by extension, the lids on those risers. One of our common themes for installation of systems is that they must be installed with monitoring and maintenance in mind. This means all components need to be installed so they are easily accessed by professionals and lend themselves to repair or replacement when necessary.

The septic tank is usually the first component other than the sewer pipe in the system and one that requires routine maintenance or inspection typically every three to five years. So convenient access is critical to providing cost-effective service.

This often means using risers to bring the access point closer to the finished grade. This makes the job easier for the service provider or inspector when assessing the condition of the tank, as well as the pumping contractor when the tank is full. By extension, it reduces the cost of maintenance for the homeowner because time does not need to be spent on locating and excavating the tank.

CHOOSE THE RIGHT MATERIAL

Risers and lids are available in a number of materials, including concrete, polyethylene, polypropylene, PVC and fiberglass. No matter the material, the riser and its connection to the tank or other risers needs to be watertight and resistant to root penetration. If roots can get in, it’s not watertight! Risers should also be structurally sound and they should not lose their shape when backfilling.

For concrete tanks, in many places a riser is cast in place during manufacture. These risers can be made of any of the materials mentioned above. Cast-in-place risers have an advantage in cold climates, as they are less subject to frost heave, which causes risers attached with joints to separate during the winter and compromises watertightness. However, even cast-in-place risers may require additional sealing or wrapping to ensure watertightness.

Since having risers cast in place can interfere with setting the tank and be in the way as the system is installed, most of what we have seen today involves casting an adapter ring into the tank opening. Then a polyethylene or polypropylene riser is connected to the adapter and secured to the tank. It is important to follow the manufacturer’s instructions for sealants required to ensure watertightness. If a concrete riser is used, both the riser and opening are tongue and grooved so there is a good tight fit. Mastic and other sealants are used to ensure watertightness. A  ny additional concrete risers should have a tongue and groove connection as well.

This configuration is the norm for newly manufactured tanks. As an installer or service provider, however, you constantly deal with older concrete tanks with no built-in riser option. So an upgrade to bring a riser to the surface for future ease of service is in order.

RETROFITS

It is a challenge to make these connections watertight. We often see a riser that is slightly larger or a different shape than the existing opening (round versus square) because this is what can be easily found. It is then set on the top of the tank lid with an attempt to mortar them into place. They become easily dislodged so when the tank is accessed you see that water and soil have entered the tank through this connection.

A retrofit solution may require affixing a butyl rubber connection to the tank top in addition to employing other sealants to ensure the connection becomes watertight. The good news is there are more products available all the time to help with this problem. Work with your local tank and pipe suppliers for help.

In general, polyethylene and fiberglass tanks will have risers built into them at the time of manufacture. Any additional risers should be of similar materials and attached according to manufacturer instructions.

Lids need to be made of sound materials with connections that make them water- and air-tight, and limit access to children and animals. Safety concerns lead some states and permitting authorities to require lids be buried under a few inches of soil to limit access. Homeowners sometimes object to lids at the surface as well. In these cases, attaching a small metal marker to the top solves the locating problem. Service providers can use a metal detector to quickly locate the tank access point.

MORE SAFETY TIPS

We feel it’s better to have the lids brought a couple of inches above the surface so that access is made easy for the service provider. It is extremely important, though, that the lid uses nonstandard fasteners or screws to make sure children, in particular, cannot gain access. Every year we hear several reports of children falling into septic tanks and being seriously injured or killed when a lid has not been securely fastened to the riser.

Additional safety devices are available that attach in the riser or at the tank opening to prevent people or animals from falling into the tank. Discuss this added safety feature with the homeowner/parent. It may be a good insurance policy and worthwhile upgrade to their system.

One other less-than-good idea relative to lids: We have seen numerous instances where concrete lids have been put on risers made of other materials. This usually leads to deformation of the riser and lack of watertightness, and creates an unsafe access concern.

Following these guidelines should make tank access and service easier, which will result in better care for septic systems, extending their life.



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