How to add irrigation to current well system?

[Orion141]

Hi all,

We have recently moved into a home with well water. I am interested in having an irrigation system put in to irrigate our lawn (~0.5-0.6 acre) and I believe our well (14gpm recovery) in theory should support this if the system is sized correctly. The challenge comes into play with the well set up and how to incorporate the irrigation system with the well system (the well system is rather elaborate due to high levels of iron and manganese from my understanding).

The current set up consists of a 1hp 10gpm submersible well pump (~125 deep) that runs into our home. Once the water enters the home it flows through a check valve and after the check valve there is a 40/60 pressure switch that controls the well pump as well as a chemical injector. The chemical injector is injecting a mix of chlorine and potassium bicarbonate. The water/chemical mix is then held in a 80 gallon galvanized air over water pressure tank. It then flows through an iron filter --> T20 everpure filter (~3GPM max based on manufacturer specs) --> 80 gallon pressure tank --> water softener --> domestic use.

I have had several irrigation contractors come through and there was concern about using the chemically treated water to irrigate the lawn as this contains pool shock and potassium bicarb and may damage the lawn (and is also an expensive mix) and they have suggested tapping into the well line before the chemical injector. I'm not sure if this is true, but nonetheless from a cost perspective (to avoid making chemical mix to treat irrigation water) it makes sense. However I am not sure it is truly simple to do this.

Can anyone think of a way to have the irrigation upstream of the check valve such that 1)the chemical injector is not called for when the irrigation system is called for, 2) the well pump could be called separately for irrigation (I would guess a separate pressure switch or relay?), 3) when the irrigation or domestic water is being used it doesnt overpressurize the leg of the system not in use (solenoid valve on the not in use system) as the check valves would not prevent this?

Thanks in advance.

Hand drawn diagram below.

 

[LLigetfa]

The water/chemical mix is then held in a 80 gallon galvanized air over water pressure tank.

The HP tank is likely to complicate things since there probably is a bleeder/snifter to make air for it. Tapping into the line prior to the check valve could affect the air making for the HP tank.

 

[Sponsor]

 

[LLigetfa]

Also note that irrigating with water that has not been iron filtered will leave iron stains on sidewalks and walls that catch any overspray.

 

[Valveman]

If you can make all your sprinkler zones exactly 12 GPM at 50 PSI that pump will not cycle itself to death and you won't even need a Cycle Stop Valve. The easiest thing might be to just tee the irrigation where you show and use the pump start relay in the sprinkler controller to turn on the pump. An extra relay after the pump start relay could cut the connection to the chemical injector pump anytime the irrigation is on. Water to the house would not be treated at this time, so running irrigation during off peak hours would be best. Adding a little 75 PSI pressure relief valve at the well head would protect the pump in the event the wires to the sprinklers got damaged and the sprinklers did not come up when the pump start relay started the pump.

 

[Orion141]

The HP tank is likely to complicate things since there probably is a bleeder/snifter to make air for it. Tapping into the line prior to the check valve could affect the air making for the HP tank.

I am not sure if there is a bleeder (I dont think there is as I do know when the well company comes they add air to both of the pressure tanks using an air compressor). Picture is below if that helps.

Regarding the iron, I definitely realize that I will have rust stains on anything that catches the overspray. Thankfully, the only thing that will be close to the sprinklers is the asphalt road (as otherwise there is mulch perimeter around house/fence/sidewalks that would keep water away). Seems to be common with the systems installed around my area. I would not have flow (GPM of 3 or less) through the everpure T20 filter to run irrigation anyways.

 

[LLigetfa]

I am not sure if there is a bleeder (I dont think there is as I do know when the well company comes they add air to both of the pressure tanks using an air compressor). Picture is below if that helps.

Sometimes they put the snifter inside the well so that picture is not conclusive. If there is no air maker, there should not be an above ground check valve as it is illegal in many jurisdictions.

The fact they manually add air to both tanks suggests no working air maker and a bad diaphragm in the captive air tank. If there really is no air maker (and not just a malfunctioning air maker), you could consider a CSV so as not to have to match the sprinkler system to the pump's GPM. Matching the sprinkler system to the pump's GPM can be iffy.

Also of note, you mention the well recovery rate which could differ from the pump's GPM rate at a given pressure and water table level (seasonal variation), so drawing at the max rate the pump can produce to prevent cycling, could in theory overdraw the well. With a CSV, you could reduce the GPM draw and still avoid cycling.

 

[Valveman]

I also do not like a check valve prior to a pressure tank that has no bleeder or air maker. However, if that line going into the tank right after the check valve is the injection line, a check valve in that location is common and even recommended. In this case it would be called a "Chem Check". They are used to keep the chemicals being injected from being able to go back towards or down the well.

Injecting chemicals at the base of the nipple to the pressure switch is not a good idea either. You can tell from the look of the nipple there is corrosion at that point, which could clog up the line to the pressure switch.

The first tank doesn't even need air as it is being used as a retention tank. The diaphragm tank is the one being used as a pressure tank. The diaphragm does need to be good as adding air regularly is not good. Water on the wrong side of the diaphragm gets contaminated and shoots into the house. You need a tank with a working diaphragm, and it is best to have the pressure switch close to the diaphragm tank, not the retention tank.

 

[Valveman]

Sometimes they put the snifter inside the well so that picture is not conclusive. If there is no air maker, there should not be an above ground check valve as it is illegal in many jurisdictions.

The fact they manually add air to both tanks suggests no working air maker and a bad diaphragm in the captive air tank. If there really is no air maker (and not just a malfunctioning air maker), you could consider a CSV so as not to have to match the sprinkler system to the pump's GPM. Matching the sprinkler system to the pump's GPM can be iffy.

Also of note, you mention the well recovery rate which could differ from the pump's GPM rate at a given pressure and water table level (seasonal variation), so drawing at the max rate the pump can produce to prevent cycling, could in theory overdraw the well. With a CSV, you could reduce the GPM draw and still avoid cycling.

Thanks and I agree with you. But I did not mention a CSV because of the chemicals being injected. The injector pump comes on when the pressure switch makes. The amount the injector puts in is in proportion to the amount the well pump produces. With some things like just chlorine you can adjust the injector to the average flow rate of the house instead of the max flow of the pump and it will work fine with a CSV.

In this case I think it important to have the right proportion of chemicals injected. This means that a CSV should not be used unless the chemical injector pump is changed to one that varies the flow according to a flow meter in the main line.

Without the CSV every zone does need to be 12 GPM as that is how much a 1HP, 10 GPM pump produces at 250' of total head.

 

[Orion141]

Thanks for the comments. I guess I am a little confused about the pressure tanks. My understanding is that they are both old school galvanized "air over water" tanks that do not contain any diaphragm as such it is completely necessary to introduce air manually to maintain pressure in these tanks? Is that not the case with galvanized air over water tanks that contain no diaphragm?

I should mention it is possible there is a snifter in the actual well casing. Supposedly this, was all done to state code.

 

[Valveman]

Pictures please! Even if there is a bleeder in the well there is no Schrader on that check valve to let air in. If they are having to add air with a compressor the air maker system isn't working even if it has one. Without a working bleeder and Schrader on the check valve, using a compressor to manually add air is the only other way to get air in the tank. That manually added air will need to be replaced every few days or the tank will be waterlogged. "State code" is only as good as the person enforcing it, and most have no clue what they are looking at.

 

[LLigetfa]

Pictures please! Even if there is a bleeder in the well there is no Schrader on that check valve to let air in.

Sometimes they will install two bleeders a few feet apart and the top bleeder acts as the snifter. Those only make a small amount of air per cycle provided the off cycle is long enough to drain all the water between the two bleeders. If the pump does not cycle often enough or the off cycle is too short, the air maker might not make enough air so needs to get topped up now and then.

 

[Unlimitednbvi]

I didn’t know about iron filtering before. I use water from the well near my house to water the entire lawn and all the plants in my small garden. I did notice some stains on concrete sidewalks, but I didn’t know the reason for that. The lawn was installed by Landscape Designers, but I installed the irrigation system myself because I thought it would be easy. I bought a specialized computer to control the watering schedule and tree sprinklers. It’s been fine ever since I installed it, but now, I want to add some filters to make the water quality better.