Please find the attached sketches for your info.
These sketches are based on our ongoing landscape design.
We have reviewed the structural beam location. The available space between the beam is too limited. Therefore, sinking the seat between the beam is not so practical.
We recommend to have a seat on top of the beam. The depth of water feature will be 0.30 m and 0.75 m for sunken seat. When we study this space, we would also like to add some trees so that we can enhance the overall atmosphere. Therefore we need 1 m soil depth for each tree. I think the overall load will be a lot lighter due to the reduction of water volume.
Please let me know if you have any question.