cvg:
From a time of concentration donsideration, a pond, or any body of water, if it is full and a]has no storage capacity, the transit time would be zero across the pond. However, for a bioswals, the time of concentration would depend on the length of the bioswale, the material in the bioswale, and the slope. It could be designed to be 90 seconds point being, for whatever reason.
From a water quality standpoint though, the pond would have the greater settling or cleaning time over the bioswale. Depends whaqt you need I guess.
Mike McCann
MMC Engineering