GRINDER PUMPS 101 14-11-03 J BETTS
This manual is a training and refresher course for all Austin Water Utility Emergency Responders who diagnose problems with Grinder Pumps in the Austin Water Utility Service Area
WHY ARE THERE GRINDER PUMPS IN OUR SYSTEM? A grinder pump is a Mini Lift Station. A grinder pump is used when a customers house is lower than the gravity system. Grinder pumps operate with floats that tell the pump to turn on or off depending on the Wet Well level. A grinder pump has a limited life as it is an electrical motor with mechanical parts that wear and fail. Limited or NO maintenance usually means the parts will wear out faster. Low pressure common force main pipes rarely cause failure due to the fact a Grinder Pump chews up all the solids and pushes the water and grit through the collection pipe system.
GRINDER SYSTEM COMPONENTS Wet Well / Can Control Panel Connection to AWU Waste Water System End of Line and Mid-Line Cleanouts on Force Main
WET WELL / CAN This is a cut away of the Wet Well / Can that is next to the property owners building. Floats located on the left of the picture communicate with the control panel giving commands to the pump to turn on off or to turn a light on the control panel indicating alarm state. A check valve should be located just outside the wet well to keep the sewage from coming back into the wet well.
CONTROL PANEL Located on the side of the building. The switch labeled H-O-A controls the pumps. H stands for Hand. Pumps On while in that position and has to be held in that position. O stands for Off. A stands for Auto (operated by the floats).
CONNECTION TO THE AWU SYSTEM There are 2 types of connections to the AWU Waste Water System. Common Low Pressure Force Main Connection Gravity Connection. Grinder to Common Low Pressure Force Main Grinder to Gravity SSL
END OF LINE AND MID-LINE CLEANOUTS If the AWU has a common low pressure system it might, not always, have a mid-line cleanout or a end of line cleanout. These cleanouts can be used to help diagnose if and where a blockage night be locate. If possible keep a vactor end on top of the cap being removed to prevent being sprayed by sewage and the loss of that sewage.
HOW TO IDENTIFY GRINDER SYSTEMS ON AWU GIS Usually a Force Main 3 and under A boxed line that has no AWU Lift Station at the end of the Force Main.
HOW TO IDENTIFY GRINDER SYSTEMS ON AWU GIS May be shown with: a green boxed line in the street red boxed line in the property Red Lift Station inside the property This picture shows a private Lift Station and private force main / yard line. AWU owns and operates what is in ROW / Easement shown in green. These designations are system specific.
AS-BUILTS SHEETS YOU MAY FIND The grid with curves on it in the right upper corner is called a pump curve sheet. This sheet is for the Engineer to design or replace the pump(s). The pump curve sheet is an indication at least one lot has a grinder pump.
AS-BUILTS SHEETS YOU MAY FIND This sheet shows a grinder pump set up detail and the two different types of connections to the AWU system detail.
AS-BUILTS DETAILS YOU MAY FIND This detail shows all the parts that were supposed to be installed as part of the grinder system connection. Use the connection detail from the subdivision as-builts to help you check what valves are located where in the service you may be trying to diagnose.
NOW FOR THE GRINDER TESTING PROCEDURE When a customer says that his grinder pump is not working properly AWU has a procedure to verify if the city line is open and the city check valve is working. AWU should be requesting the property owner or plumber to operate the pump during testing. AWU cannot tell whether a pump is working properly. AWU cannot tell a customer what to do if his pump cannot pump through the whole system. They need to consult a plumber who has experience with grinder pumps. AWU CAN tell a customer if the city side is open / flowing. If you can not verify the city side is flowing due to valves in the wrong positions or the check valve cannot be verified a work order needs to be written to bring the connection to the current standard.
TESTING AWU PIPE FROM ROW TO DISCHARGE MH This test will show if the line from Valve 10 to the discharge point is open. 2 Swing check valve #10 should close preventing AWU material to enter property.
TESTING AWU CHECK VALVE #10 This test will show if the line from the PO s pump through valve #10 to the valve 9B is open. If the PO s pump is not operating properly valve 10 may not open. If valve 10 gets stuck in the closed position this test will only show that the pump is not able to pump to the valve or through the valve 10. 2 Swing check valve #10 should open allowing private sewage into the city force main.
ALWAYS find and open the Profile or As-Built for the location of the call Grinder or Gravity system.
A FEW EXAMPLES FROM THE FIELD: Please look carefully at the examples and note the differences in the pictures, pages and details. If you see something that does not look right, something is missing, or is not to current standards please point it out and discuss it with the presenter or your supervisor.
Example 1 GRANDVIEW HILLS SECTION EIGHT
Grinder Connection Valve 9A
EXAMPLE 2 Grandview Hills Section 4
EXAMPLE 3 Canyon Creek West Section 3
Valve 9C Cleanout MH on Low Pressure Force main
EXAMPLE 4 The Reserve @ Riverplace Section 1
Note this system has Septic Tanks as shown in the pictures. According to the detail to the left the septic tank is private and the ROW is the point of connection.
QUESTIONS?