Re: Detention Pond Inverted Pipe Outlet
- From: John Drake <john@xxxxxxxxxxx>
- Date: Tue, 03 Jan 2006 19:02:32 GMT
In article <1133967984.818101.205990@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Miner99 <jds_colorado@xxxxxxxxx> wrote:
> We are designing a detention pond/wetland system. (see
> http://www.georgiastormwater.com/vol2/3-2-2.pdf for more info). The
> outlet structure must address water quality, and our regs call for the
> use of a steel plate with drilled holes, however our drainage is quite
> large (2000+ acres), and the aesthetics of a massive steel plate and
> constructability of this plate has made us look for other alternatives.
> What we are considering as an outlet for the pond are inverted pipes,
> where the outlet is higher than the inlet. Water is flowing uphill, go
> figure. This is maintain a permanent pool, and will draw water from the
> bottom of the water column, which in theory is cleaner and cooler. Has
> anyone built or designed something like this? Are the subject to being
> silted in? We have beavers in the area that plug up every pipe, so we
> have to be able to easily maintain it. Do you model an inverted pipe
> as culvert under inlet control? Or would a orifice be more appropriate
> (looking at the inlet), or even a weir (looking at the outlet)?
Hi - I don't read this site very often, don't know if you've had any other
replies.
Your last suggestion sounds right for modelling the system - you need an
orifice for the inlet, followed by a pipe (if it is long enough for
friction to be an issue), followed by a weir to give you a control at the
outlet. This combination ought to represent the system properly.
The main problem with an inverted pipe is achieving a sufficient
self-cleaning velocity, as it runs full-bore at all flow rates. It is sure
to need regular maintenance, even without the beavers, so I would suggest
stoplogs at the inlet chamber so you can dewater the whole pipe for
cleaning from time to time.
Hope this is useful.
--
John M Drake
Edinburgh
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