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Monday, August 10, 2015

Irrigation Pump System

This past week our irrigation system took an unfortunate turn for the worst as both of the main pumps failed. The failure was unexpected but not entirely surprising as both pumps were close to 15 years old! With a normal life expectancy of 8-10 years depending on water quality and use, 15 years isn't bad. It was a very tough situation to be in during July/August, but we took the opportunity to investigate the system in depth to prevent future problems. 

Our irrigation system is run by two 75 hp vertical turbine pumps, each capable of supplying 890 gpm at 110 psi, in addition to a 5 hp pressure maintenance pump. The pumps sit in a 13' x 4' concrete tube known as a wet well. The wet well holds water taken from a stream or pond and reduces the likelihood of contamination from weeds, debris, and foreign objects getting sucked through the pumps. 

The old pumps were removed using a crane and a scuba diving team inspected the wet well and intake pipe in the pond. The scuba team was used to ensure the wet well was in good shape without cracks or holes in addition to checking the intake pipe and screen prior to installing the new pumps.  The current wet well is intact and looks good but the intake pipe is very close to the sediment in the pond that has built up over many years. In the near future, the pond will have to be dredged to remove this organic matter build up and ensure we maintain a clear intake pipe going forward.

Old turbine pumps located between holes 3 and 7 North

To get by before the new pumps are installed, a temporary pump has been installed next to our existing pump station. The temporary pump is capable of supplying 450 gpm and will pressurize the system to the normal 110 psi. This allows approximately 12 irrigation heads to run simultaneously at full pressure in addition to a few hoses for hand watering. Currently, the new pumps are scheduled to be installed on Friday, August 14th.

A crane was used to remove the old pumps

Wet well inspected by scuba diving team

Debris found on the wet well bottom after pumping out sludge

Heading in for intake pipe inspection 
Organic matter sludge pumped out from around intake pipe screen