seasonal above ground water line for farm use 1

[pperlich]

Hi everyone. I'm PV engineer for carbon steel vessels by day and a farmer/rancher by night. I need to run a water line to provide water to my cows during the warm months. Currently I am using a 325 gal (US) tank in the back of a pick up truck to carry water, and I'm tired of doing it this way.

I'm planning on running the water line above ground along the perimeter fence. The total length from the current water source to the point of use is about 1600'. The good news is that I'm only looking at about 8' rise over that distance. Accounting for the hottest days and future growth of my herd, I'm wanting to design for delivering 600 gal per day. I will have the water pumped to a storage tank which will supply the water to the stock tank via gravity. This way during peak demand, the water will already be in the storage tank.

My well is on a 40/60 psi switch. I was thinking of using HDPE pipe. I was looking at flow calculations using this site: https://hdpeapp.com/#/application. I know this isn't the most comprehensive way of doing this, but...
Over 1600':
1" Pipe @ 5 GPM = 13 psi pressure drop (2 hour run time per day)
3/4" Pipe @ 5 GPM = 39 psi pressure drop (2 hour run time per day)
3/4" Pipe @ 2.5 GPM = 11 psi pressure drop (4 hour run time per day)

The 3/4" pipe and fittings will obviously be more affordable, but will it flow enough?
Is HDPE pipe a good choice for above ground water pipe? UV exposure?

I will also have to account for temperature/length changes, but should be able to accommodate that.

Am I overthinking this? Probably.

 

[Snickster]

So you are going to use your existing well pump that kicks in at 40 psig and kicks out at 60 psig? You are going to tie-in to the existing system at the pump outlet? You are going to control the flow manually with a throttle valve to 5 gpm with rotometer set up? How will you control the flow? Do you have a pressure versus flow curve for the existing pump? So the 8 foot elevation difference includes the height of the water level of the new storage tank?

 

[LittleInch]

Do you have the pump curve for your pump?

Can you post it.

Only then can we see whether this would work well.

The simplest system from the data you've provided is to run 3/4" pipe and just let the pump output balance the flow - but that why we need the pump curve. Hence all you need to do is have a fill valve at the far end or some sort of float switch once the tank fills up. But the point remains - Are you trying to do the fill on a continuous basis as the cows drink it or on a batch basis twice a day?

I do know my BIL who has a farm sometimes struggles in the summer to keep the water going as they are thirsty buggers at times.

You should then get >5GPM if the pump can do it.

HDPE is good above ground, but you need to buy black pipe to guard against UV. Or just scrape it into the ground by a foot or so and you will be fine. Try not to lay it in straight lines as PE does expand a lot and could easily jump out of the ground or start to kink if you don't allow it somewhere to expand.

 

[pperlich]

Unfortunately I do not have a pump curve for my well pump. I was planning on leaving the water supply open to the storage tank all the time and regulating flow with a float valve on the storage tank. The stock tank would also be on a float valve. Based on how long it takes to fill the 325 gallon truck tank that I'm using, at the hydrant I'm getting 10-12 gpm roughly. So all I'm really trying to estimate is if I can get 600 gallon in 24 hours back there. It doesn't really matter to me if its 10, 5, 2.5 or 1 GPM. Does that make sense?

The 8 foot elevation increase includes the storage tank elevation above the ground.

Thank you, Phil

 

[LittleInch]

The problem with that approach is that your pump will start, then stop then restart constantly. Whilst you're laying your pipe lay a cable. Then set a float switch to start at say half-full and turn off when full.

You need to find the details of the pump otherwise you have no idea what is going to happen.

 

[pperlich]

Hmm. Shouldn't the well tank sufficiently reduce the starts/stops? I have a submerged jet well pump, 3/4 HP (need to confirm). Beyond that information I'm not sure how I could find a pump curve for my pump. The previous owner of the property didn't keep (or share) any records related to the well system. Is finding the exact intersection of the pump curve to the system curve really that important? I have been thinking that as long as I could reasonably demonstrate that the intersection was at a point that would deliver enough water per day that would be sufficient even if I didn't know exactly what the flow rate would be.

 

[LittleInch]

What "Well tank"?

Do you mean another tank?

I've had a look at a 0.75 hp jet pump and it looks like it will do 5gpm at about 40 psi.

The issue I see is short cycling when flow is low. The pressure drops to below 40psi, pump starts, runs for 15 seconds then hits 60 psi and stops. Do that for days on end and you will burn your motor out very quickly.

 

[dvd]

You may be able to get some assistance with this project from your state USDA service center - https://www.nrcs.usda.gov/state-offices

https://www.nrcs.usda.gov/sites/default/files/2022-09/stelprdb1167367-watering-facility.pdf

 

[Snickster]

I get a pressure drop of 26 psi in 1600 feet of 3/4 DR 13.5 HDPE with 0.88" inside diameter at 5 gpm. Add about 4 psi for elevation change and you get 30 psi total pressure drop at 5 gpm.

You indicate that your pump appears to do 10 to 12 gpm when filling the portable tank but actual pressure at discharge at this time is unknown. Pump kicks in at 40 psig so I believe the 40 psig corresponds to 10 gpm flowrate on pump curve or somewhat around there. So you should be able to get at least 5 gpm at 30 psi even with some other outlets in your house operating.

I assume the well tank you indicated is a bladder volume tank that fills up with water and shuts pump off at 60 psig and then drains down to 40 psig until the pump starts up again to prevent cycling of the pump at low demand.

The attached HDPE pipe data sheet indicates it has UV protection.

 

[MintJulep]

Pumping untreated well water through 1,600 feet of black pipe laid out on the ground and into a tank seems like a good setup for breeding bacteria.

Do some research on water quality control and treatment before you do this.

 

[pperlich]

What "Well tank"?

Do you mean another tank?

I've had a look at a 0.75 hp jet pump and it looks like it will do 5gpm at about 40 psi.

The issue I see is short cycling when flow is low. The pressure drops to below 40psi, pump starts, runs for 15 seconds then hits 60 psi and stops. Do that for days on end and you will burn your motor out very quickly.

Yes, I have a bladder tank that the well pump fills and your typical 40/60 pressure switch.

 

[pperlich]

You may be able to get some assistance with this project from your state USDA service center - https://www.nrcs.usda.gov/state-offices

https://www.nrcs.usda.gov/sites/default/files/2022-09/stelprdb1167367-watering-facility.pdf

I have used the NRCS EQIP program for some projects in the past. In this case, the project I am doing doesn't qualify.

 

[pperlich]

I get a pressure drop of 26 psi in 1600 feet of 3/4 DR 13.5 HDPE with 0.88" inside diameter at 5 gpm. Add about 4 psi for elevation change and you get 30 psi total pressure drop at 5 gpm.

You indicate that your pump appears to do 10 to 12 gpm when filling the portable tank but actual pressure at discharge at this time is unknown. Pump kicks in at 40 psig so I believe the 40 psig corresponds to 10 gpm flowrate on pump curve or somewhat around there. So you should be able to get at least 5 gpm at 30 psi even with some other outlets in your house operating.

I assume the well tank you indicated is a bladder volume tank that fills up with water and shuts pump off at 60 psig and then drains down to 40 psig until the pump starts up again to prevent cycling of the pump at low demand.

The attached HDPE pipe data sheet indicates it has UV protection.

Thank you very much!

 

[LittleInch]

Yes, I have a bladder tank that the well pump fills and your typical 40/60 pressure switch.

These are ok for certain uses, but still lead to many start stops. As you have two tanks at the other end it makes no sense to drip feed both.

Fill the first tank on a batch basis low / high switch then let it dribble into the cattle drinking trough on a level control. That will be so much better than trying to use this like a mains water supply to one user.

Anyway be sure to let us know what you decide to do and send us some pictures!

 

[pperlich]

These are ok for certain uses, but still lead to many start stops. As you have two tanks at the other end it makes no sense to drip feed both.

Fill the first tank on a batch basis low / high switch then let it dribble into the cattle drinking trough on a level control. That will be so much better than trying to use this like a mains water supply to one user.

Anyway be sure to let us know what you decide to do and send us some pictures!

I think divorcing this system from the rest of the farm would be pretty complex, and batch filling may take hours.
My well pump supplies the house and farm. If I tried to use a low/high switch on the storage tank and not rely on the bladder tank & pressure switch, then I'd need complex controls for the well pump and extra valves to keep water supplied to the house and barnyard while batch filling the back storage tank. I would also need to run power to the back tank for the switch as well, right?

 

[LittleInch]

Ah, you didn't tell us that bit... I thought this was a dedicated pump for the cows.

Why add another tank? Just feed the stock tank direct.