Self Cleaning Sump

//Self Cleaning Sump
Self Cleaning Sump 2018-01-03T18:32:17+00:00
peristaltic pumps

Self Cleaning Sump

The Gorman-Rupp Self Cleaning Sump (SCS) is a revolution in wastewater pump station wet well design. The SCS is an easy to install sloping collector pipe (fabricated from heavy duty HDPE) that is directly connected to the control manhole, and used in conjunction with Gorman-Rupp self priming sewage pumps.

The Self Cleaning Sump has been designed to replace the conventional cylindrical wet well and to remove the flaws associated with this current design. The negatives of the conventional design are considered to be the amount of intervention (number of personnel per call and the number of calls) required with these stations, the risks to operators associated with accessing the wet well for blockage removal and maintenance, and the longevity and reliability of equipment.

The aim of the SCS design is to:

Self Cleaning Sump – Video

SCS Easy Installation

The SCS is delivered to site:

1

Suction lines and service lines are welded into place

2

The SCS is placed into position, ready for grouting to the control manhole

3

A PVC sleave is positioned over the suction and service lines

4

The SCS is almost ready for back-filling

 

Minimise Blockages

Because the self cleaning sump [SCS] has a relatively small volume, the time between pumping cycles is much shorter than usual. This means that the items that normally block pumps [stringy materials such as rags, hair, wet wipes etc] do not have a chance to settle out and matt together. If these items don’t get the time to matt together, they remain small and easily pumpable.

During the pump cycle, the pump is run at full speed at the start and completion of each cycle. During the middle of the cycle, the water level is kept at a level that promotes the fastest movement of particles. The whole aim is to keep the solids in suspension and moving and that is what the design of the SCS and the mode of operation are all about.

See the below ball of rags that stopped this large submersible pump, because the rags are in a large ball. They have balled because of settling out and matting together.

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Eliminate Sediment Build-up

Sucker trucks are sometimes needed to remove sediment that has built up in the slow moving areas of the conventional wet well arrangement. This is not permitted to happen with the SCS concept.

During the pump cycle, the pump is run at full speed at the start and completion of each cycle. During the middle of the cycle, the water level is kept at a level that promotes the fastest movement of particles. The whole aim is to keep the solids in suspension and moving and that is what the design of the SCS and the mode of operation are all about.

The use of VFD controls means that there is no issue with the number of starts each of the motors has in any particular hour.

Eliminate Fat Build-up

Sucker trucks are sometimes needed to remove fat that has built up in the conventional wet well arrangement. This happens because in the conventional submersible system, the oil and fat sit on the surface and is left behind after each pump cycle. Not only are sucker trucks used, but specialised wet well cleaners and chemicals are also called upon to treat the symptom. The SCS system treats the cause. It keeps fat moving, then suck’s it out with each and every cycle, not giving it a chance to build up to a thick blanket requiring intervention.

During the pump cycle in the SCS system mode of operation, the pump is run at full speed at the start and at the completion of each cycle. During the middle of the cycle, the water level is kept at a level that promotes the fastest movement of particles and floating matter. The whole aim is to keep the solids in suspension and moving, and to remove them with each cycle.

The use of VFD controls means that there is no issue with the number of starts each of the motors has in any particular hour.

 

Eliminate air Entrainment 

Air entrainment can shorten bearing and seal life of sewage pumps, and it can also build up in discharge lines, increasing energy consumption. Air can get into pumps as water cascades into wet wells, carrying air with it.

Baffles are often used to guide the water away from the suction inlet of pump units, which does help eliminate this problem, but it can add a significant amount to pump station costs to install.

The SCS avoids air entrainment naturally, by having the suction lines at the farthest point from sewer inlets.

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Reduce Energy Consumption

It is the use of VFD control and the mode of operation of our SCS system that enables a reduction in energy consumption. The pump starts at full speed, but after the “regulation level” is reached within the SCS system, the pump slows to a speed that keeps the wastewater at a pre-determined level. This level is decided based on the level in the system that permits the fastest flow into the SCS, therefore keeping all solids in suspension.

The system holds the regulation level for 3-5 minutes, depending on the quantity of fat/ oil/ grease coming into the system.

Because this is the bulk of the time of the pumping cycle, the pump spends more time at the lower flow, and hence lower head because of the decrease in friction losses through the discharge piping. Because the head is lower, the energy consumption is reduced.

Greatly Reduce Blockages in Pumps

The SCS system is designed to keep solids moving and prevent them from settling out and “balling” and “matting” together. Because the hair, rags and wet wipes will be pumped before they get a chance to ball and matt together, the pumps are much less likely to block because of this.

Also, Gorman-Rupp Super T Series pumps can be supplied with the most advanced system for handling solids laden liquids. Called the ERADICATOR ™ Solids management System, the technology incorporates design features to minimise downtime and make the operator’s job easier and quicker.

Greatly reduce maintenance cost

The SCS system, combined with and above ground Gorman-Rupp pump station would be a revolution to any Water Authority or Council not currently using self priming pumps.

There would be no need for the following “accepted” operational “interventions”:-

  • The use of sucker trucks for removing silt or fat build-up
  • The use of chemicals to break up and remove fat deposits
  • The use of well washers to clean off fat
  • The use of baffles to direct flow away from pump suction inlet’s
  • The replacement of discharge [duck-foot] bends. Because there is none.
  • The replacement of submersible pump guide rails or lifting cranes. Because pumps are surface mounted.
  • The use of cranes to lift pumps out of wet wells [because pumps are above ground].
  • The use of 3 persons to attend site for a blockage removal [because only one person is needed to attend a self priming pump station].
  • The use of specialised vehicles with lifting hoists.
  • The use of 3 persons to perform routine maintenance such as oil changes, gauge checks, valve maintenance etc, because these tasks can safely be performed at a self priming pump station with only one person, and without the need for confined spaces access or the need to open wet well lids.
  • The use of 3 persons and many hours to adjust pump clearances or change wear rings, as Gorman-Rupp above ground pumps only require one operator for less than 30 minutes to perform this task.

Reduce Civil Costs

Because of the much smaller volume of the SCS, the excavation “footprint” can be smaller. Also, the cost of the HDPE inclined collector pipe of the SCS is less expensive than the conventional cylindrical wet well normally associated with submersible sewage pumping stations.

A “conventional” system also has a below ground valve vault that needs to be excavated, installed and fitted out. This is not needed for a Gorman-Rupp packaged pump station, because the valves are all packaged into the pump station which comes complete with the pumps and all interconnecting piping.