Can I achieve 90secs detention in a stormwater drainage system's pipes
Can I achieve 90secs detention in a stormwater drainage system's pipes
(OP)
Is it possible to achieve 90seconds detention for storm water quality in a storm drainage system's pipes instead of using a detention box? Is this a good practice?





RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
I've never heard of "90 second detention" for water quality before, wondering where that comes from. I usually see 24 to 72 hours, not seconds.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
Mike McCann
MMC Engineering
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
I want to know if the pipes in the system can serve that Purpose, and if it is a good practice.
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
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
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
Some of yall are a little off on this. You absolutely can get sediment to fall out of flow in a pipe or channel where water is moving. (slowly)
The math for sediment pond design is based in its roots on Stokes Velocity. If you want to trap 80% of your sediment, you do a grain size distribution analysis, figure out what size is 80% or larger, then figure out how long it takes that grain size to fall at Stokes Velocity through a viscous fluid (water) to the bottom of your pipe. Then you size your pipe to reduce the velocity enough so the grain has time to hit the bottom of the pipe before your water is discharged out the other side. ADS a while back built some water quality devices on this premise, which were large HDPEs with pre-welded baffles in them, and a couple of inspection/cleanout manholes.
In fact, that same Stokes Law (falling velocity of spheres) analysis is at the heart of the nomagraphs used in the Georgia Erosion and Sedimentation Control Manual for sizing sediment ponds.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Can I achieve 90secs detention in a stormwater drainage system's pipes
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com