Vaccum Sewer Systems / Consequences of Changing Isolation Valves Locations

Isolation valves should be located as close to the object to be isolated as PRACTICAL.

Vacuum is generated in the vacuum station and the sewage in the pipeline is sucked into the collecting pit or tank in the vacuum station. The collected sewage is transferred by pumps to a sewage treatment plant. There are two options as for vacuum generation. The one is ejector system and the other vacuum pump. With the ejector system, the sewage in the collecting pit is recalculated by the circulation pumps through the special ejector which generates the vacuum. Read more ……..

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Dear " just and engineer "

firstly , thanks a lot for the informative brief that you gave which reflects your valuable experience in this field,

actually i was referring to the " division valves " or the isolation gate valves which are installed for the maintenance purpose of the vacuum lines not the vacuum pit valves. it was just a change in it`s location due to it`s falling very near to the road curbs at site .. something forced the installation team to relocate it closer to the vacuum sub main lines ..

actually i have another question for you here , due to some site conditions also sometimes you have to re-route your line to avoid the obstacles you face , in the Australian code, there is some standard drawings which define the max no. of lifts to be added consecutively on a line ( 5 consecutive lifts with a min of 6 meter between each lift ) , the question here will it affect the performance in the line if due to site conditions , 45 degree bends came in between these lifts(i mean the same case here of 5 consecutive lifts mentioned above ,total no. of 3 bends added ) to obtain the required routing ? in other words can the " saw tooth profile " be routed with 45 degree bends or it is a must to be a unidirectional line ?

thanks

i'm not experienced with vacumm sewer systems, but i think it replaces the need for pumping stations. sewage must either flow by gravity, pumping or by an an other method to deliver the sewage to the plant. changing the location of the valve might raise sewage levels or the need for a larger vacuum pump.

sorry jae. you have a ga from me.

For my clarification, are you talking about these that are the household pit actuation valves.

Or these valves that are the section isolation valves back at the collection point.

For those interested, this system currently services around 300 households with capacity to 1200. The maximum depth of pipe is around 3000mm below ground level. These valves are also at ground level.

It is over 900m to the furthest collection point in the system. Almost 50% of the system is below the water table at high tide.

Vacuum was selected so that system leaks would not release untreated material into the environment. We do monitor conductivity (salinity) to check for leaks.

There are also a couple of inlets on marina mooring sites for boats to pump out. Again, no spills over the water since system is always negative pressure.

The tank in the foreground is 6m long and 3m diameter maintained at vacuum condition. It has internal baffles to stop grit from the inlets scouring holes in the far side of the tank.

Vacuum systems though, do have some challenges.

What you see is around 15 years old.

I suppose the suck-it-and-see approach is not one to use here?