Building Pool where Septic Tank Was


Active member
May 22, 2020
Kelowna, Canada

We are building a pool and the excavation area includes the location of our Septic Tank that was recently decommissioned. The tank will be removed during excavation. It is located where our shallow end will be (48" steel wall vinyl liner pool). The tank is plastic and currently extends to a depth of about 6.5' or about 3 feet deeper than the finished pool depth.

Just curious how we deal with this? Do we just will it in with 3/4" crush rock and compact to bring it back up to correct grade; or do we have to do something else?

Rich D

Bronze Supporter
Aug 3, 2018
Compacted 3/4 crushed stone would be best. If there is any sign of water I would install a sump pit to the lower part of the excavation. Just be sure they dig down to undisturbed soil. If there is water present a sump needs to be installed outside the limits of the pool and deeper than the bottom of the deepest excavation elevation. This will allow them dig to dry undisturbed soil. You do not want to see them trying to muck out the hole with water in it and then throw stone into 6" of mucky water. You should be able to see the soil in the entire area where the bottom of the pool goes and it should be solid and free of loose material before stone is placed. Water running over hard virgin ground to the pump is ok. Unfortunately a lot of pool builders have very little knowledge of proper excavation and dewatering and can not even recognize undisturbed virgin soil.