Flooding in Sanitary Pumping Stations

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INTRODUCTION
Pumping stations are facilities including pumps and equipment for pumping fluids from one place to another. They are used for a variety of infrastructure systems, such as the supply of water to canals, the drainage of low-lying land, and the removal of sewage to processing sites.
There are three types of Systems which are related to Sanitary Pumping Stations
1) Municipal - These systems are designed to serve a given natural drainage area and are part of the public sanitary sewer system.
2) Industrial - These are designed to serve a given industry and, generally pump to the public sanitary sewers. They are usually owned and operated by the industry.
3) Residential - These serve either individuals or multi-family complexes.
FLOW RATE DETERMINATION
The Flow rate estimation of residential sewage is based on population numbers. The flow rate varies on daily and weekly cycles basis, the variation is in the range of 0.5...1.5 times average flow. Industrial effluent should be estimated on a case by case basis, depending on the plant type. The amount of leakage water present depends on a number of variables, such as water table level, local rainfall and soil characteristics and general condition of the subterranean pipework. It can be estimated as units per pipeline length unit, e.g. kilometer or as a ratio related to quantity of the sewage.
The determination of the Daily Average Flow is set by knowing the service area to be provided. This service area should be determined by considering the present and future aspects of the land area, population increase and size of the sanitary pumping station that is to be installed. The Peak flow rate is then calculated by multiplying the Daily Average Flow with the peaking factor (g...

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...(in.)
The maximum surge pressure, P, then equals P =- aV/2.31g.
DESIGN CONSIDERATIONS
The following are few more design aspects which should also be considered in the design of a sanitary pump.
1) Odor control
2) Net positive suction head
3) Air/vacuum valves
4) Safety
5) Wet well dead zone
CONCLUSION
The possibility of flooding at the pumping station with consequent environmental damage must be taken into account. For this reason sewage pumping stations have two pumps in duty-standby configuration, with each pump capable of handling peak flow. Thus flooding will not occur in situations when one pump is out of order or being shut down for service. If pumping station capacity is based on two pumps operating in parallel, a third pump should be provided as standby.

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