Hi, I am designing a concrete box that will be used as a bio-filter. What solid pressures have other engineers used? In addition, the box will hold water for at least some time. Should I include water pressure in my design?
Water pressure should definitely be included in the design. But is the box buried? If so, the external soil pressure on the box will probably control during construction, when the box is empty.
Is there any issue with designing for full fluid pressure? You might get a little lower pressure depending on your fill medium, but it will probably be 60-80% of fluid pressure. (Assuming a gravity system)
Dave's point is correct, but I typically see these boxes above-grade.