sewer pump station

[LdPmtc]

good day everyone

what is the norm on sizing the pump flow rate for a sewer pump station, average inflow or peak inflow/
guides on the sizing of the sump volume?
for how many emergency storage volume should be allowed for?

thks

 

[cvg]

try the google search bar at the top - this subject has been discussed before. A couple of links that may help are below:

http://www.eng-tips.com/viewthread.cfm?qid=200375

http://www.eng-tips.com/viewthread.cfm?qid=132126

 

[BigInch]

if you could only do average, once you had a peak flow, you'd never be able to recover your tank levels again until inflows fell to levels as much below average, and for an equivalent time, as your peak flow was above average.

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"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[jgailla]

LdPmtc,
If you are in the U.S., you should probably have a copy of Ten States Standards for Wastewater Design. This is referenced in many state codes. Another free download is the Unified Facilities Criteria (UFC, formerly TM-Technical Manuals) from the U.S. military. I can't recall the UFC number, but if you google UFC wastewater it should be easy to find.
In general, the pumps for a typical lift station (serving a population between 100 and 10,000) are sized for the peak flow. It is required to have one additional pump not used in the design, i.e. a pump in a duplex pump station is sized for the peak flow using only one pump.
There is typically no storage volume. Pumps are required to handle the peak flow without storage. The sump volume between the pump on and pump off level is sized using the cycle time of the pumps, usually 12 to 15 minutes.

 

[LdPmtc]

what is a good rule of thum for the emergency storage volume to be provided (hours) to cated for down time on the pump system?

 

[cvg]

you need a duplex pump station and backup generator for power outage. how long will it take to switch to the backup pump in the duplex or to hook up the generator?

 

[jgailla]

LdPmtc,
Since you would have one extra pump, each pump would be serviced separately and there is theoretically no down time for service.
For a small lift station (maybe 2,000 capita or less), a vac truck would be used to suck out the sewage during a power failure. Larger stations are required to have emergency back up power as cvg indicated.
An alarm setting is used, generally 6" inches above the both pumps on setting. I've never designed a lift station that came out less than 10 feet below ground, so during a failure the sewer would be surcharged for some time before it backed up into a building.
I have not calculated an emergency storage volume and have never been asked to calculate one. The lift station top is generally below finished floor of any buildings it serves and I try to grade the site so that an overflow would flow away from the station.