Install septic tank risers and covers by uncovering the existing openings and cleaning the top of the tank. Install the adapter ring, and attach the risers to the tank so they are a few inches under the surface of the lawn. Place the new covers on the risers, and backfill the hole. Replace the sod, or reseed the area so grass hides the risers and covers.
Septic tank risers and covers provide easier access to the tank for inspection and service. They are available in concrete, polyethylene or polyvinylchloride. Concrete risers are the least expensive of the three, but they are the most difficult to install, primarily due to their weight. Polyethylene risers are easier to install and lighter, but they sometimes leak water and sewer gases. PVC risers are the lightest in weight and easiest to install, but they are the most expensive.
The adapter ring ensures a tight fit between the tank opening and the riser. Some adapters require mixing concrete and adding it around the adapter to cement it in place. Others attach by packing the area with butyl rope.
If the tank is in an inconspicuous area where the covers are not in the way of landscaping, owners can extend the risers so they are above ground for easier access. Placing them below the sod provides easy access, but requires locating the riser and removing the grass to access the tank.