Sprinkler water supply surges after new well points

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Valkyrie

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Here's the story! I have an existing sprinkler system drawing off 4 wells spread out all over the place and it got so it was down to just a trickle. Washed down 4 new wells using Brady T-pack & 2" pvc pipe method. I have water table level @ 5' below sod surface. Each well has 2 4' sections of 1 1/4" well point stacked and each well is deep enough to get 9'-10'(+) standing water when a weighted string is dropped. Wells are dug and plumbed in an H pattern with 1 1/2" sch. 40 pvc with the top & bottom of the H being 8' apart and the two legs being 5' apart. Main pipe running from the center of horizontal cross about 7' to 2 HP "Simer" centrifugal sprinkler system pump. Have vertical check valve just before pump intake. When I run this set up in my existing sprinkler system it has great performance for about 5 minutes then starts to surge like it's running out of water. I'm confident about the integrity of all the pvc joints. All the homes around me have the same kind of shallow well set up for sprinkler systems. I find it hard to fathom this system could run out of water and if I had a leak wouldn't it surge right from the start instead of after 5 minutes. The previous set up had a 1 HP Sears 35 years + pump. Is my 2 HP to large maybe and demanding too much water. Also cannot find any open lines in my 2 zone sprinkler system that would cause loss of back pressure. Any insight or suggestions would be appreciated. I’m worn out, my arms and shoulders ache and my mind is totally frustrated. TIA, Valkyrie.
 

Speedbump

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First of all, 8' of screen in a shallow well may be too much. You didn't say how deep you went or if you are sure your in a water vein. You may be sucking air once you draw on the wells for a while. You might want to check with the neighbors that are having good luck with their wells and find out the depth of their wells and the construction method. No two areas are identical, so nobody here can tell you where you will find water.

A two horse centrifugal is way way way too big of a pump. It can do around 80+ gallons per minute and will cavitate like crazy pulling on shallow wells like that. Your 1hp sears was probably a bit too big.

bob...
 

Valkyrie

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Thanks for the response speedbump. At least talking to someone about this mess is relieving my stress. Got the 2 HP at a steal $. The old 1 HP sears ran this sprinkler for 37 years. Still runs but housing is 1/2 rusted away. The Brady literature that came with the T-pack suggested that there should be 4' of screen for every 1/4 HP, thus 2 4" sections stacked in 4 wells. I'm down far enough that I have 10'-11' standing water. That's 24" + over the top of the screen. The water table is 5' (+-) below sod level(West coast Florida) in this whole area that I live in. I have watched commercial guys do exactly the same thing I did not 15 feet from my house for the neighbor. Everyone has the same basic setup except that most I know have a 1 HP pump. Some have air bladder setup. We are kind of sitting on an aquifer. No problem finding water with a post hole digger. If I'm sucking air cavities in the water table using too big a pump, would it do anything by reducing the draw with a gate valve? Or do I need to drop to a 3/4 HP?
TIA Valkyrie
 
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Speedbump

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The size of the pump doesn't matter as far as pulling on the wells goes. A 1/2hp pump can pull just as hard as a 2hp pump. Problem is the wasting of electricity. No 1-1/4" well on a sand point can give the kind of water that a 3/4hp centrifugal pump could pull.

Just because you can dig a hole and get water does not mean your in a water vein. An aquifer is deep, a vein is shallow as in surface water. Your looking for a vein of very clean sand with no clay, dirt, color or anything else beside clean sand. If the vein is dirty in the least, it's not a vein.

Commercial drillers use drill rigs, not garden hoses and wash points. So the guys you are seeing doing these wells are not pros. They are usually weekend warriors. That's why you will see a self priming centrifugal on practically every one they do. They don't know that a jet pump would have performed far better.

bob...
 
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