View Full Version : Irrigation system fed from a river
09-03-2011, 08:03 AM
Iím a homeowner designing an irrigation system from a river. I am knowledgeable in the process of designs and installing systems (worked for an installer during my younger days). All systems we installed used city water to supply the system.
I have access and rights (approved by the DEP) to use less then 100 GPM from a river in my yard. However Iíll only use about 30 GPM. I have all the calculations needed for PSI loss, pipe sizing, pump sizing etc.
My question is what type of head would be the best way to go. I will install a filter on the main line (VU-Flow 30 or 60 mesh). My original thought was to use a Hunter I-20 or Rainbird 5000 but with all the research Iíve done on this site not sure if the Maxi-paw would be a better choice for river water. What makes me nervous are the negative responses to the Maxi-paw.
Not sure if this will help, but I will use a Goulds submersible pump (25GS20) with a 2 hp motor. The pump will be in a PVC well screen and rest on cinderblocks a few inched off the river bottom.
Iím grateful for any feedback I can get (negative to positive).
09-03-2011, 08:47 AM
As a DIY guy, there won't be any issues with the Maxipaws you can't handle. They are a great choice for dirty water. Rainbird PESB scrubber valves will handle such water.
Make sure you have a pressure relief valve in your plumbing, since that pump can go beyond 130 psi
09-03-2011, 11:22 AM
wet boots - thanks for the reply and the heads up with the pressure relief valve. The pump/irrigation shop I'm working with did not mention that high of PSI.
About the valve, I'll look into the rainbirds and do some research (don't know too much about them. However what are your thoughts on the Irritrol 700?
09-03-2011, 11:58 AM
If you get the PESB valves and Maxipaw heads, you won't have to filter the water so fine.
Pressure is one reason I favor the use of jet pumps for a system I install using poly pipe, since those pumps don't develop enough pressure to cause damage. That it is also an above-ground pump eliminates the problem of putting power wires into an accessible body of water, especially one you don't own. The Goulds pump I would have chosen is their J15S, with 25 gpm of useful flow, if it doesn't have to lift the water too much. In fact, with a 5-foot lift, and running Maxipaw heads, you can get almost as much water with the 1 HP J10S
09-03-2011, 12:26 PM
Wet Boots - don't think I can use that pump. The dealer and I looked at many pumps that will draw up water, however I have a 25' rise to the bank of the river and another 15' elevation change to my house. 25' is at the max those pumps can handle. With the output needed of 25 - 30 GPM and a working pressure of 65 PSI the dealer suggested the 25GS20.
Rotor question, is there any gear rotors that would hold up to the dirty water? If I go with the Maxi-paw what are some of the common issues that is has?
09-03-2011, 01:11 PM
Rotor question, is there any gear rotors that would hold up to the dirty water?
In my travels, I've never seen rotors pumping from a river. However, depending on the turbidity, you could zone the hell out of the system and use the largest nozzles. Sand and gear-drives are not good friends, though. Weather-Matic makes a good "scrubber valve" you might look into. :)
09-03-2011, 01:27 PM
Are you clear about having approval to place a pump in the river? I don't take that as a given, not in New Jersey. (and if you tick off the powers that be, the DEP could pull the river-water permit)
Completely off the beaten path, but possible when you border a river with good flow, is a Ram Pump, which uses the force of the moving river water to pump it uphill to your location. No elevation worries with those, and no electricity used, and no issues with power wires. Once the water reaches an uphill holding tank, a jet pump can take over.
What size is the property? How much area is being watered?
09-03-2011, 01:50 PM
I'll touch base with Trenton after the weekend just to make sure. I'm not sure I'll have the current needed for the ram pump. Here are some pictures of the elevation change.
09-03-2011, 02:03 PM
Looks like pretty clear water. :clapping:
09-03-2011, 02:09 PM
I take it the river can rise that 17-20 feet? In the absence of a pump in the river (including a ram pump, which won't work there) you could place a jet pump as close to water level as you dare. If an equivalent to a hinged floating dock could be devised, it would be possible to have a pump that stays a few feet above river level, giving you maximum performance.
How many acres of lawn are you watering?
09-03-2011, 02:38 PM
Mike - yes it does not rain for about a week the water gets pretty clear. However after the rain it turns cloudy. Right now it looks chocolate mike after the hurricane.
Wet Boots - the most I've seen this rises is 8 feet, and this is extreme (example post hurricane Irene). Most of the time it will only rise about 4 feet. I only have an acre to water. Calculated 6 zones with a max of 24 GPM per zone.
I'm not too familiar with the jet pump, how is this different from the centrifuge? Would it be able to push water 30' elevation change 150' and maintain 35 - 30 GPM with about 65PSI? I like the idea about the floating dock, I could make that work.
Just wanted to say thanks again for all the feedback!
09-03-2011, 03:52 PM
24-30 gpm for an acre is kind of a luxury. As for 65 psi, that all depends on where you are measuring it. You can easily manage an acre's watering with 15 gpm, especially from pumped surface water, because there is never a conflict with household use.
If you add a few feet to your uppermost river level, and set your pump there, you would have a lift of 10-15 feet. The Goulds J15S will give you 20 gpm at that lift, plenty to work with. The pressure won't be 65 psi at your property's highest spot, but that is not any particular problem.
A jet pump is basically a centrifugal pump with a portion of the outlet water routed back to the inlet, in order to increase the outlet pressure. It makes a pretty good fit with sprinkler systems, as you can see from performance charts.
the Maxipaw heads are plenty reliable as a sprinkler mechanism. The knock against them is that they have to operate from an underground enclosure which is open when the sprinkler is operating. Careful setting of the heads (slightly above grade) will minimize problems.
Besides the dirty-water capabilities, the Maxipaw gives you good coverage with less pressure than gear drive rotors need, and that figures in big-time on a pumped-water system. You can look at charts that make all the common rotor heads look great at 30 psi head pressure, but Maxipaws deliver great low pressure performance (http://www.rainbird.com/documents/turf/chart_2045MaxiPaw.pdf) with a spread of coverage the gear-drive heads can't match.
09-03-2011, 04:52 PM
Yup, its a 'wish' to have that GPM. The 65 PSI is at the pump. With the PSI loss for filter, mainline, elevation change, valves, laterals, fittings I calculated about 40 - 45 PSI at the heads. Being a son of an engineer, I created a jig to run different heads from my house water to test some of my calculations. Here is the Maxi with the blue nozzle shooing water at 30' at about 30 PSI.
09-03-2011, 04:59 PM
Wet Boots - sorry, forgot to add a 'thanks' for info on the pump. Going to go to the Goulds web site to dig around.
09-03-2011, 05:00 PM
Maxi is the best (jeez, did I just say that?) for your application. However, if the client has certain types of dogs, those heads will be toast very soon. :cry: Not too happy about the choice of pressure gauge.
09-03-2011, 05:14 PM
Mike - the client is me and I have an old Golder Retriever. Should I be concerned? The gauge is the Lowe's special. Looked to build this jig on the cheap to test test some the heads I bought. I know that Orbit is pretty cheap however this jig will be tossed out once my system is built.
09-03-2011, 05:23 PM
Those blue nozzles will even work well at 25 psi, and at that pressure, the gear-drive rotors look ill. Not that you design for 25 psi for rotors, of course, but your application will have have some pressure variations, as the river level changes.
If you didn't have to lift the water 20 feet, you could easily have a system on an acre fed by the 1 HP jet pump.
09-03-2011, 05:31 PM
Some dogs REALLY LIKE impacts. Terriers are my favorite, though my Aussie will attack them, too. Might be a good idea to set your jig up and see how your Retriever reacts to it. I once went to a cold call where the client said all his heads were destroyed, I looked at them and they were chewed to failure. I asked him what the hell had happened and he said, "fire your remote." I did, and two Jack Russels came bounding out of nowhere and attacked the heads. I shut the system down and said, "good dogs". Replaced the system with rotors and the poor dogs had to find something else to do.
09-03-2011, 05:37 PM
You made me laugh. I had the impact going just the other day so I can take some measurements and she sat under it getting wet. She is too lazy to chase anything these days. :laugh:
09-03-2011, 05:38 PM
At the same time mike dogs like regular rotors too
My dog will run to every single rotor that is on and bite it:laugh:
I just dealt with a pump system ran off a slough with I-20's and Rain Bird PGA valves. 8 years old.. Other then the pump freezing (which we replaced) it's been working fine.. Time will tell
09-03-2011, 05:52 PM
At the same time mike dogs like regular rotors too
My dog will run to every single rotor that is on and bite it:laugh:
When you go into business for yourself, fire the zones and let the pup go, as long as the client is not home. :rolleyes:
09-04-2011, 08:58 AM
Wet Boots - thanks on the suggestion on the jet pump. Did some research yesterday and found this pump. Looks like I will still be able to maintain good pressure at 20 GPM. Your thoughts on this?
09-04-2011, 09:30 AM
Again, what are you doing with this "good pressure" that cannot be done with less? There is no law that requires 50+ psi at the base of a rotor head. Also, going up in flow increases your pipe costs, and a multi-stage pump like the HSJ series can blow a poly mainline if a zone valve closes unexpectedly.
09-04-2011, 09:50 AM
I would like to have 35-40 PSI at the heads if possible. If I can get a PSI at the pump at 60 PSI I will be able to achieve this. I have calculated the following:
150' schd 40 2" mainline- 1 PSI loss
Filter 2" - 3 PSI loss
Valve 1.5"- 3 PSI loss
Elevation change (20' aftger pump) - 9 PSI
Laterals poly 1.5" - 4 PSI
Fittings - 5 PSI
Heads - 35 PSI
This totals 60 PSI
If I cannot get 60 at the pump, sure I could run a lower pressure.
09-04-2011, 10:26 AM
9 psi loss in your laterals and fittings does not compute. Almost all the pipe friction losses can be cut to minimal, except for valves and funny pipe and their elbows, which take away a psi or two, because of turbulence.
I don't see you getting your money back by spending the extra hundreds on a multistage pump. That said, extra pressure is always nice as screwup insurance.
If you were on level ground next to a lake, you could do good work with the 1 HP jet pump.
Aside from Goulds, you can get a 1-1/2 HP jet pump from Flint & Walling, and theirs seems to offer more performance. 18 gpm would get you where you need to be, and the lower flows let you use 1-inch zone valves.
09-04-2011, 11:33 AM
Thanks Wet Boots, let me look into the F&W pump.
09-04-2011, 11:54 AM
the F&W pump might be pricey, though ~ if you were doing an all-rotor system with Maxipaws and scrubber valves, you might get away without a filter/strainer, provided you had a trustworthy inlet screen in the river.
09-04-2011, 11:58 AM
I'm going with Maxi-paws and looking into the Rainbird PESB (or similar). If I can get away with not using the filter that's a few bucks I can save (as well as PSI loss). Would that be risky?
09-04-2011, 12:38 PM
It depends on the inlet screen. If the river is shallow, you might have to try to float a screen. I don't know of any ruggedly-constructed ones like I would want in flowing water.
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