flow regulator

[siblak]

Does anybody have experience with flow regulator in combined sewer?

I want to limit the flow of a combined sewer before it enters a future interceptor. Since I don't want to oversized the future interceptor, it will be designed for sanitary flow only so the flow from the combined sewer has to be limited to the sanitary flow during rain. The sanitary flow is small (20 houses, around 60m3/d).

thanks

siblak

 

[BobPE]

siblak:

The design has more to do with the CSO discharge to the environment that the discharge to the interceptor during CSO events. I have a few favorite designs to convey flow to interceptors, but they really depend on the site conditions. The main focus of the design will be on how you will discharge the storm flow. CSO regulators typically consist of a chamber with a weir and "flap" valve and a connection to the interceptor. Your weir settings are designed to account for what flows you what to accept in the interceptor and what you want to bypass. Make the chamber maintenance friendly as you will need to be in there to record bypass flow (if you are in the states) and clean debris.

Let us know more of your thoughts on how you want to design it and maybe we can helpo more.

BobPE

 

[Maury]

Dealing with combined sewers is a major problem with no good answers. Designing a restrictor to limit the flow into the sanitary sewer shouldn't be difficult, but you still ahve to manage the flow form the combined sewer:

1. Construct an over flow outlet. This is a cheap way to go but has environmental consequences and you my not have a legal place to discharge.

2. Provide a temporary storage basin for the excess flow, then pump it to the sanitary system when the system can handle it. The flow will still be treated, but the treatment plant has to be capable of handling the flow volume.

3. Provide a separate treatment facility for the combined sewer overflow.

 

[siblak]

thanks for your reply.


I can discharge into the river when its raining.

I need to control the flow in the interceptor cause the treatment plant is not design for runoff flow. The problem is that the flow to control are really low.(around 3 l/s) and the interceptor is a 300 mm diam. pipe. I know there are some flow regulator available but from what I see there are unable to control flow lower than 10 l/s unless you take one with a very small inlet (smaller than 4'').


siblak

 

[semo]

As Bob stated, why not use weir(s). You can install a structure with a weir on the side. Set the weir level to allow normal flow through the sewer line and excess flow to spill over and bypass. Using 2 weirs (1 in-line and one on the side) will allow you to better determine your flow split at high rates. You will get some extra flow in the interceptor; but, you can set the weirs to determine how much.

Also as Maury stated. What are you going to do with the bypass flow. You say the river; but, (I don't know where you are) most states won't allow direct discharge without primary treatment at a minimum.

Maybe you can install a holding basin and then pump it back as Maury mentioned or gravity it back into a manhole downstream with a controlled discharge.

 

[siblak]

Semo

Set the weir level to allow normal flow through the sewer line and excess flow to spill over and bypass.

How do you do that with flow like 2l/s???

 

[semo]

I did say in-line weir which may not have been the best term. An actual weir may tend to hold back solids at low/normal flows which you don't want. You can use other means of flow measuring such as a parshall flume, open channel, etc.

Say you were to use open channel flow and make a concrete structure in your sewer line which has a rectangular channel width of 6-inches (still allows 3-inch solids to pass) and a slope of 0.004 ft/ft. A flow of 2 l/s (31.5 gpm) would give a depth of 0.11 ft. Therefore, in this structure normal flow has a depth of 0.11 ft. If you place a sharp crested weir along the side of this channel with the weir level set at 0.11 ft, part of any flow greater than 2 l/s would bypass.

Sizing the width of this weir will help determine how much bypasses and how much flows to the interceptor. The wider the side weir, the more is bypassed as the water level rises.

Also, I would not look at normal flow. You don't want to bypass a peak day flow that does not have storm water. You need to look at your flow records and set a level that does not bypass raw sewage on dry days. These wet weather flow levels will also let you look at what is bypassed and what goes to the interceptor.

These are just ideas i've used with success and you should do the calcs with your actual design. Others may also have methods they use for similar situations.

 

[nackra]

I was working on CSO regulator designs a few years ago - you might consider the following:

http://www.copa.zen.co.uk/hydroslide.htm

There is another product that I will check design archive, but I believe that it is better application for larger Q situations.

Good Luck

 

[siblak]

Nackra

thanks. Do you have any experience or feedback using those regulators??

siblak

 

[nackra]

During the design phase I interviewed collection staff with client (Midwestern US) to review alternate regulator devices. Staff preferred vortex regulator over the hydroslide device, but based on your relatively low flow requirements the vortex regulator is probably NOT best choice. The client staff indicated that this device would probably work "ok" but they had not used any of the hydroslides as of late 1990's. My project was "tabled" at 60-percent design level and I have since relocated to west coast. To date I do not think that the project has been reactivated for completion.

I'd suggest checking w/ manufacturer for installation list then call collection/maintenance staff for direct experience/feedback.

 

[Aneurin01]

I work for a UK based company who produces Flow Regulators for foul and storm flows. Our product range can limit flows between 2 and 438l/s. Should you require further information on flow regulators I would be more than happy to assist

Hope this helps

 

[siblak]

Aneurin01

Thanks for your reply.
Could you please send me informations of your products.

siblaktron@hotmail.com

thanks