How to Install a Septic Tank Risers
Septic tank manhole covers buried underground require excavation when tanks need routine maintenance or a problem has occurred. To reduce the cost of excavation labor and to ease septic tank accessibility, manhole risers should be added. Risers are made out of plastic or concrete. Plastic manhole risers use reinforcing ribs on their exteriors that can trap soil. This trapped soil can lift the riser from the tank. Concrete risers are flat on the outside and will not trap soil. Both materials are prone to leaking unless they are properly sealed.
- Excavate the soil covering the septic tank's cover using a shovel or an excavator. Use an excavator carefully when close to the tank as excess pressure can break the septic tank lid.
- Pull up on the manhole covers to remove them from the tank. If the manhole covers do not easily lift from the tank, attach a chain from the bucket of the excavator to the manhole cover and slowly lift the bucket. Some septic installers seal the manhole covers with tar sealant and this adhesive needs to be broken.
- Clean the concrete where the riser will contact the tank top. Remove any dirt and debris with a trowel and a wire brush.
- Heat the tar sealant to increase its adhesive ability by leaving it in direct sunlight for at least 15 minutes.
- Press the tar sealant onto the concrete where the manhole riser will rest with a trowel. Lift the riser onto the tar sealant and press down.
- Lift the manhole cover and place it over the newly installed riser to keep out soil during backfilling.
- Replace the excavated soil onto the top of the septic tank using a shovel or excavator. Hand-shovel soil next to the manhole risers so they are not disturbed and their seals stay intact.
Working around excavating equipment and septic tanks is dangerous. Use safety equipment and keep children far away.