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Discussion Starter · #1 ·
I recently designed and installed an irrigation system on nearly 3/4 of an acre. We live in the Ozarks and the lawn slopes downhill at what is considered around here "a mild grade". The limestone bedrock is very close to the surface in many areas of the yard.

I followed all the guidelines I could find on designing the system, and for the most part, I am thrilled with the results. However, I have one problem area. One section of the yard is a large ovoid with the narrow end surrounded by a driveway on both sides. This is at the bottom of the slope and water naturally drains to the area. I planted a "rain garden" (feet wet plants) at the bottom even before the irrigation system was contemplated. I have three lines running down the hill, each a separate zone. The heads are 36 to 40 feet apart and I am running Hunter PGP's. I have great head to head coverage, but now the lower end is turning into a swamp. I am establishing new zoysia from seed in the area, so I am trying to keep the lawn moist everywhere. But when the top of the slope is thoroughly dry, the bottom is still swampy. I have reduced the nozzle size on all the downhill sprayers and cut the arc down on the middle bottom so that it does not cover the worst of the area. I think the worst of the problem is coming not from the system when it is running, but when it shuts off. When the valves close everything in the line drains out of the bottom sprayer. On the advise of my seed supplier, I am watering 3 times a day for a short duration, but that means that the swamp is getting 3 times as much line drainage as it normally would...or 6 times as much if you consider every other day as the "norm".

Is there something I could add to the valves that would prevent the line from draining? Or should I not worry about it, since the three drains a day will only be for a couple of weeks? Any other thoughts or ideas? Thanks in advance for any insights you can offer.
 

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How long and what size are the three zone lines running downhill? How far apart are they from each other? Do you have any idea of how much water is getting pooled up at the bottom of your slope? I used to live in SE Kansas and also had a cabin south of you close to Kimberling so I'm familiar with the terrain.

You mention you designed the system yourself, did you factor in precipitation and absorbtion rates?

~
 

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First step would be to get the PGP check valve model. Or change the low heads to I-20s with a check valve. These check valves under the head will hold up to 10' of elevation so hopefully you are not exceeding that. If you are, it means that the line will continue to drain until the check valve spring exceeds the water head pressure.



Jerry
 

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Discussion Starter · #4 ·
The East zone is 140 feet from valve to last head. The first 40 feet are 1" Class 200 PVC and the balance is 3/4" Class 200. The Central zone is 200 feet, with the first 60 feet 1". The West zone is 200 feet with 100 feet of 1". They run fairly parallel 40 feet apart. At the point where the ovoid narrows, the central zone doglegs and has the last spot on what would appear to be the West zone.

Did I consider precipitation and absorbtion rates? No. I laid everything out for head to head coverage, which I thought was as much consideration as was needed. Now I am discovering that the 90 degree heads are putting out twice as much water on their area as the 180's and 4 times as much as the 360's. Hunter's PGP's have salvaged that problem, since their variety of tips supplied will allow you to decrease the precip without killing your radius. Absorbtion rate would be a nightmare to try to quantify on this lot, since the soil type changes every few feet. The currently swampy area is a very rocky (limestone) loam. 100 feet upslope it is sandy clay full of igneous rocks and sandstone.
 

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Discussion Starter · #5 ·
jerryrwm said:
First step would be to get the PGP check valve model. Or change the low heads to I-20s with a check valve. These check valves under the head will hold up to 10' of elevation so hopefully you are not exceeding that. If you are, it means that the line will continue to drain until the check valve spring exceeds the water head pressure.
Jerry
Thanks, Jerry. I took a look at Hunter's website. They also offer a check valve to install into normal PGP's that will hold back 2 feet. The last head in each line is probably at least 20 feet below the valve, but if I add the field install kits to each head in the line, it would greatly reduce --- though not eliminate the amount of water draining. The alternative would be to dig up and replace the lower two units I guess.
 

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Nozzle selection will not totally correct the standing water problem. It will help it by reducing the applied water in some areas. As you have found out, the 90° nozzle needs to supply 1/2 the GPM of the 180° nozzle which needs to supply 1/2 the GPM of the 360° nozzle. This will make the precipitation rate more equal over the area.

The low-head drainage will not be changed by changing nozzles however. The volume of water draining out of the pipe remains constant every time the system is run. Even if you go from 4.0 gpm nozzles to 2.0 gpm nozzles the amount of water in the pipe doesn't change. Installing check valves either in the heads or even in the lateral or directly under the head will help solve the drainage problem.

Jerry
 

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Just read your post and went and found this information.

PVC Adjustable Spring Check Valves
PVC Adjustable Check Valve
Series 1205 FIPT x FIPT PVC Adjustable Check Valve

Series 1235 FIPT x MIPT

Use to restrain head pressure in elevated irrigation lines.
Ideal for preventing syphoning in slope and nursery irrigation

* Male or female threaded connection
* Iron Pipe sizes ½" to 1½"
* 200 PSI static pressure rating @ 72ºF
* Adjustable from 5 lbs. to 15 lbs. spring tension
* EPDM seal

In addition to the standard features of Flo's Check Valve, this is adjustable, providing 5lbs to 15 lbs spring tension to retain a column of water 12 to 36 foot head.


http://www.flocontrol.com/t_check.htm#Adjustable

One or more of these on the line and you could have the problem whipped.

Jerry
 

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Discussion Starter · #10 ·
Thanks for your help, Jerry. I understand that changing tips isn't going to help the drainage problem -- which is, I think, the only problem I have. I was watching the swamp grow and changing tips to minimize the water before I saw that the real culprit was line drainage. I am going to go check out the line check valves you linked right now.
 

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Discussion Starter · #11 ·
The line check valve certainly looks like it would solve the problem. However, my boxes are really full already, and i don't think I could squeeze one of those in after the valve without tearing out every box installation. Since I just finished 8 days of power and hand raking, I am somewhat reluctant to take that route. :dizzy:

Think I will start with Hunter's field install check valves for the heads.
 

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JonHolland said:
Where is Bryan to come in here and tell you to water for shorter amounts of time, with delays between zones, several times a day?
Man are you lucky I just checked this. If I had seen that after working in the dark and early AM this Sunday to make up for whimping out in this heat yesterday, I would have made a very improper response, I am sure.

But, since he already stated that the problem was from low head drainage and being made worse by the cycling for seed........
Yeah, 'nuf said :)

Now, if the check valves help, I would encourage him to consider cycle and soak periods when he gets back to watering established turf :gunsfirin
 

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jeffinsgf said:
The line check valve certainly looks like it would solve the problem. However, my boxes are really full already, and i don't think I could squeeze one of those in after the valve without tearing out every box installation. Since I just finished 8 days of power and hand raking, I am somewhat reluctant to take that route. :dizzy:

Think I will start with Hunter's field install check valves for the heads.
Those check valves will go in the lateral line where it is going down the hill. If they are at the valve box, you still have all the pipe downstream to the last head draining and have done nothing to solve the problem.

For sake of argument let's say you have 200' from valve on top of hill to last head at bottom of hill. The elevation change is 20'. if you used an I-20 with a check valve, it would hold 10' of that elevation head. Then you would go back up the lateral line up the hill to a point where you are about 10'-11' below the valve location. (we're talking verticle elevation below)This could be anywhere along the lateral line. It might be near the middle of the slope, or wherever that 10' elevation change is. Cut the lateral line and install one of those adjustable check valves. Now your lateral line remains full (nearly anyway) and you have eliminated the low head drainage. The check valves will open when a valve opens and forces water under pressure into the line. The check valves will also open when blowing out the lines for winterization.

Hope this explanation makes sense. It is perfectly clear to me. (chuckle)

Jerry R
 

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Discussion Starter · #14 ·
Thanks, Jerry. I was thinking that the check valve was placed after the control valve at the head of the lateral, and would work sort of like holding your finger on a straw. I now see what you're talking about. I am going to go to Ewing in the morning and see if the PGP's with check valve fit in the same housing that the normal PGP fits in. If so, that seems like greatest gain for the least amount of disruption. If that dries up my swamp, that will be that. If not, I'll get out the laser level and see just how much drop I am really dealing with.
 

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Discussion Starter · #15 ·
Okay, line drainage is completely solved. I changed the 3 rotors at the bottom of the lines near the swampy area to i20's. That helped a lot, but the heads above then drained and the water followed the trenches to the bottom. Ewing doesn't carry the check valve version of the PGP, or at least my Ewing doesn't stock them. I took a critical view of the elevation drop and decided to try the field install check valves. They're rated for 2 feet and it appeared to me that my drop from head to head wasn't much more than that. For $1.09 per head my problem is solved. It is dead simple to put the check valves in. You just pull the rotor out of the case, pull the filter screen out and replace it with the new filter screen with check valve. I noticed no difference in spray pattern, velocity, or radius. Kind of makes you wonder why they just don't put the check valve on all PGP's --- of course then there would be one fewer reason to upgrade to i20's.

Anyway, I thought I would pass along the info that the check valves work, are easy to install, and a cheap solution to line drainage problems your customers might face.
 

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jeffinsgf said:
Okay, line drainage is completely solved. I changed the 3 rotors at the bottom of the lines near the swampy area to i20's. That helped a lot, but the heads above then drained and the water followed the trenches to the bottom. Ewing doesn't carry the check valve version of the PGP, or at least my Ewing doesn't stock them. I took a critical view of the elevation drop and decided to try the field install check valves. They're rated for 2 feet and it appeared to me that my drop from head to head wasn't much more than that. For $1.09 per head my problem is solved. It is dead simple to put the check valves in. You just pull the rotor out of the case, pull the filter screen out and replace it with the new filter screen with check valve. I noticed no difference in spray pattern, velocity, or radius. Kind of makes you wonder why they just don't put the check valve on all PGP's --- of course then there would be one fewer reason to upgrade to i20's.

Anyway, I thought I would pass along the info that the check valves work, are easy to install, and a cheap solution to line drainage problems your customers might face.
Great to see a problem solved. FYI, there are valid reasons for not having check valves in place as well. The kit you used should have been readily available to convert the PGP's. I hope it wasn't a big deal getting them in. I wonder if the cost of PGP's w/ check is a full buck higher than those w/o. Think I'll ask next time I'm at the parts counter. This would be another reason I like my CR500's. Each case comes w/ 20 rubber washers that when installed are the check valve. Without the rubber, no seal takes place, but if I need it, it is an easy (and provided at no charge) retro fit.
 

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JonHolland said:
Bryan, if you mail me a CR500, I promise I'll think about using them.

:)
ROFLMAO, No Jon, you need that brand name recognition. Somebody has to use those vinatge PGP's :) Nothing wrong with them at all, They've been fantastic for around 30 years.

Free samples? I can't even get a free hat these days. And the last free hat I did get said Hunter on it!! I think they paid for lunch that day too! payup
 

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bicmudpuppy said:
Free samples? I can't even get a free hat these days. And the last free hat I did get said Hunter on it!! I think they paid for lunch that day too! payup
Hunter mailed us a couple hats, a lunch cooler, and a bag (one of those net ones) with the Hunter logo on it after we placed a substantial order.

I prefer hats with my companys name on them, but I do use the lunch cooler :)
 

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JonHolland said:
Hunter mailed us a couple hats, a lunch cooler, and a bag (one of those net ones) with the Hunter logo on it after we placed a substantial order.

I prefer hats with my companys name on them, but I do use the lunch cooler :)
WOW, two hats?? I'm impressed. :) Substantial must have meant 20+ cases of product!
 
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