Above ground these concrete tank pads appear to be a simple thick load bearing concrete pad. The time, labor and engineering that have gone into these 3’ 6” thick pads is quite extensive. Last year we were lucky enough to pour two different diffusion tanks for Safeway and another refrigeration company. While they were both complicated the Safeway project took the cake. Below both sets of pads are shown. The other pad we did has all of the same specs as the Safeway pad but extra excavation, structural fill and shoring were not needed.

What started out to be a simple 1’ 6” thick 10’ x 10’ pad turned into a 3’6” pad needing extra 7’
of excavation and an 18’ x 18’ hole. After a geological report was done, they found the existing subgrade
was too poor to hold a concrete pad and tank. We needed to then cut out 18’ x 18’ of concrete and
excavate 7’ down to put in new structural fill. With the excavation shoring was needed for safety. Once
the tear out and excavation was done, we put the shoring in place. With the shoring in place, we were
then able to haul in engineered approved structural fill. In order to pass the upcoming necessary
compaction test we had to place the fill in lifts. Meaning we would add layer of fill, drop in the walk
behind trench compactor, compact that layer of fill and then do the process all over again until we
reached 4’ thick of fill.

After the compaction test was completed, it was time to create the rebar cage. The engineered
plans called for #6 rebar (3/4” thick) 1-foot O.C. (on center) on the top and bottom with 1 at mid-level all
the way around as well. This large cage had to be all tied together floating so there was 3” of spacing on
all sides.

Once the cage was in place, inspected and approved it was finally time to pour. This project
called for 4,500 PSI concrete which would be tested before we could pour to ensure the concrete met all
requirements. Slowly pouring in the concrete was necessary as we needed to ensure the rebar cage
would not move and we could properly vibrate the concrete. The concrete was poured and a standard
broom finish was added to the top. Once our portion of the project was done it was time for another
company to install the diffusion tanks on top of our pads.