I am looking for some feedback on a project I am considering. My home was just placed on town sewer and is allowing people to reuse their septic tanks as cisterns for irrigation purposes. I already collect all my roof runoff and carry it to daylight on a low part of my property. I am fortunate in that the drain line runs right past the septic tank. It would be trivial to connect it to the tank.
My home currently has an in-ground system using Hunter PGP heads. Each zone has 6 heads. I can configure each head to run anywhere from .1 to 5 GPM. I figured 2gpm is a good starting point, thats 12gpm per zone.
These heads can run as low as 30psi, so I can start with that. The tank bottom is 8ft below grade.
Using the formula to calculate HP=QHS/e3956
Where
Q=flow in gpm; H=head in feet;S=1 for water; e=efficiency(80%); 3956=conversion factor to end up with HP
To determine Head feet from psi (@ 30 psi and 50 psi)
30 psi*2.307psi/ft= 69 ft; total H=69ft+8ft.
(50 psi*2.307psi/ft=115ft: total H=115+8ft)
12gpm x 77 ft x 1 /(0.80)x 3956 = .29HP
(12gpm x 123 x 1 / (0.8) x 3956 = .47HP)
So this would indicate a ½ hp submersible pump would work to drive my system. Would an off the shelf sump pump from the big box store work in this application? Would a sump burnout with this much use?
Since my septic is only 1000gallons, I think I can really only use it to water 2 zones. 1000 gallons at 1" per week will not cover my ½ acre of lawn in August.
Thoughts?
My home currently has an in-ground system using Hunter PGP heads. Each zone has 6 heads. I can configure each head to run anywhere from .1 to 5 GPM. I figured 2gpm is a good starting point, thats 12gpm per zone.
These heads can run as low as 30psi, so I can start with that. The tank bottom is 8ft below grade.
Using the formula to calculate HP=QHS/e3956
Where
Q=flow in gpm; H=head in feet;S=1 for water; e=efficiency(80%); 3956=conversion factor to end up with HP
To determine Head feet from psi (@ 30 psi and 50 psi)
30 psi*2.307psi/ft= 69 ft; total H=69ft+8ft.
(50 psi*2.307psi/ft=115ft: total H=115+8ft)
12gpm x 77 ft x 1 /(0.80)x 3956 = .29HP
(12gpm x 123 x 1 / (0.8) x 3956 = .47HP)
So this would indicate a ½ hp submersible pump would work to drive my system. Would an off the shelf sump pump from the big box store work in this application? Would a sump burnout with this much use?
Since my septic is only 1000gallons, I think I can really only use it to water 2 zones. 1000 gallons at 1" per week will not cover my ½ acre of lawn in August.
Thoughts?
