Dry spots in the lawn

[G Burton]

I have dry spots in the lawn. More watering would overwater the rest of the lawn. Spot watering does not work well with my work schedule. The dry spots are about 3 feet from sprinker heads, so it may be that much of the spray goes over them, but that doesn't seem to be a problem with other sprinker heads. I don't see how I can manipulate the sprinkers to improve the spray.

I have a way of dealing with the dry spots, but I am an amature, and I'm not sure my method is the best

[G Henslee]

yes. don't post in a non-binary group using html.

[G Burton]

There are a couple of things I forgot to mention.

I live in Western Garden zone 14

My soil is clay with a wimply layer of topsoil.

I have used Gypsom (in the form of Soil Buster) in the past, and (like the Kellogs Topper) I don't know how much it is helping. I would like comments on that too. I now have some pure Gypsom instead of the Soil Buster.

I will monitor this posting for a while to see what I can learn before I do anything, but unless I get some better ideas I plan to:

1) Put down more gypsom

I have a way of dealing with the dry spots, but I am an amature, and I'm not sure my method is the best

[Tom Jaszewski]

Sprinklers work by "heads to head coverage" Meaning the next head over from the dry spot is providing the water !!!

Check your nozzle sizing. For example if the nozzles are 12' they should not be spaced more than 11-12 feet apart!

the lawn. Spot watering does not work well with my work schedule. The dry spots are about 3 feet from sprinker heads, so it may be that much of the spray goes over them, but that doesn't seem to be a problem with other sprinker heads. I don't see how I can manipulate the sprinkers to improve the spray.

not sure my method is the best -- or is even working, for that matter.. What I have done in the past is pour some spongy soil on top of the dry spots in the expectation that it will retain the moisture. I have used Kellogs Topper to pour directly on top of the dry spots. It seems to work, but I'm not sure. I have seen improvement in some spots, but not the worst ones. That may be because I didn't put enough on.

Screwdriver only goes in about 1.5" in the dry spots, but I can push it in to most of my lawn fairly easily to about 6"

Acts of creation are ordinarily reserved for gods and poets. To plant a pine, one need only own a shovel.

-- Aldo Leopold

[G Burton]

I've checked that, and I am within spec. In fact, the problem is just a few feet from the head.

[Tom Jaszewski]

Once more....you have problem with uniformity. After hundreds of homeowners consultations over 20 years I'm stilling willing to bet you have a coverage and not a soil problem!!! Put some tuna cans out in brown and green spots, run your irrigation for 5 minutes and measure depth> then report back! Acts of creation are ordinarily reserved for gods and poets. To plant a pine, one need only own a shovel.

-- Aldo Leopold

[G Burton]

I only had 2 tuna cans, but I ran the experiment twice.

The first time, there wes no discernable difference in depth. I put one can in the dryest spot and another in one of the greener spotts about 2 ft away. I used the depth gage on my verniers, and measured 3 places in each can. In both cans, I measured .120-.135 in in 3 places. I didn't take and average, because the range was within the margin of measuring error.

The second time, I ran the sprinklers for 10 minutes instead of 5. I compared another "dryest spot" (where the screwdriver stops at about 1.5") with one of the greenest spots in the lawn only about 2 ft away and where the screwdriver goes in 6" easily. I took the average of 4 readings in both cases. In the dryest spot, the average was .263 and the average in the greenest spot was .276.

I did this in the afternoon, and there is always wind here in the afternoon, so that could be goofing up the data. The wind today is mild, but it's here. I water at 4 am, when there is seldom wind. I will repeat the measurement after tomorrow's first (12 minute) watering, with the cans in the same place.

In the meantime, I would sure love to hear anything you have to say on using gypsom and topper soil. You may have missed my second posting about that. If so, please check my "More Info" posting.

[G Burton]

The wind made a difference, and it appears that you were absolutely right. In 12 min of sprinkling, I collected .132" at the bad spot and .305" in the good spot.

Several of the bad spots are about 3 ft from a 12 ft spray nozzle, which makes me suspect overspraying. I just measured my pressure, and got 62 psi upstream of the solenoids. I set the pressure high because I have 16 sprinklers each in 2 of my sections. It would be very difficult to add more sections.

I am using the better Rainbird sprinklers -- not the Home Depot version. What would be the best approach?

a. Reduce the pressure? If so, what to? b. Change the sprinkler nozzles? If so, what to? c. Something else.

[Tom Jaszewski]

Increasing pressure does NOT solve inadequate flow! Please review the chat from RB and calculate flow demand.

've created a misting system!!!

At 30PSI if all were half sprays you'd have a 20GPM demand. I'm approximating and not taking into account friction loss etc.

Not to bad, what you need to add is another valve.....

Have you confirmed head to head coverage? There are heads within 11-12' of the head with the dry spot....sorry to repeat, but it's another one of the MOST likely problems with installation! (I have seen both flow and distribution uniformity problems)

Congratulations, most don't realize that HD sells crap!!!

Optimum charted pressure is 30PSI

series heads are capable of 70PSI but are foggers at that pressure even with adequate flow!

Here our calciferous high dissolved solids level in city water DOES distort spry nozzles after a few years.

Acts of creation are ordinarily reserved for gods and poets. To plant a pine, one need only own a shovel.

-- Aldo Leopold

[G Burton]

I still believe the head-to-head coverage is OK, but I will check it again.

You have undoubtedly helped me a great deal, and I really appreciate it.

I now have all the information I need to get it right.

Thanks!!!

[Steveo]

Good job, Tom Jaszewski. Nice to know we have an irrigation guy on board.

"G Burt> I still believe the head-to-head coverage is OK, but I will check it > again. >

[G Burton]

Please bear with me just a little bit longer.

I put a pressure meter between my pressure regulator and my solenoid valves. If I set the pressure to 30 psi when the sprinkers are on, then turn the sprinklers off, the meter jumps up to 65 psi and stays there. I am thinking that my pressure regulator is bad. My pressure regulator is a Watts 35B, but I can't find flow rate information on it.

Does it sound like a bad regulator to you?

Where can I find flow rate information on it.

BTW, I have 17 heads, not 16. The total flow should be about 22 GPM per the RB chart.

[Tom Jaszewski]

I'm clueless here...but here's what watts writes...

System Pressure If the downstream system pressure is higher than the set pressure under no flow conditions, the cause could be thermal expansion, pressure creep or dirt/debris on the seat. Thermal expansion occurs whenever water is heated in a closed system. The system is closed when supply pressure exceeds 150psi, or a check valve or backflow preventer is installed in the supply piping. You must make provisions for pressure relief protection of your plumbing system and components. The use of a relief valve such as the Watts 530C, BRV, Governor 80, or 3L or potable water expansion tank such as the Watts DET, PLT or DETA may be required. To determine if this is the result of thermal expansion, try briefly opening the cold water tap. If the increased pressure is caused by thermal expansion, the pressure will immediately be relieved and the system will return to the set pressure. Watts offers a pressure test gauge, model 276H300 to assist you in determining if you have high water pressure. The 276H300 when attached to a hose bibb registers the highest pressure reading over the period of time it is left on the system. USA: 815 Chestnut St., No.Andover, MA 01845-6098; Canada: 5435 North Service Rd., Burlington, ONT. L7L

5H7;

1. Ordering Code 3. Type Number
2. Size of Valve 4. Model shown on Nameplate Watts 276H300

Simple google search....

Acts of creation are ordinarily reserved for gods and poets. To plant a pine, one need only own a shovel.

-- Aldo Leopold

[G Burton]

Thanks again! I will do more investigation about the regulator. I may have an obstruction coming into the house. The inlet pipe is 3/4", so I don't think I should be having this pressure problem. I am clueless now too, but I will get it figured out.

I think I allowed myself to get distracted by the regulator. It's a problem that should be addressed (or at least understood), and I will do that. However the fact remains that when the sprinklers are on, I have 30 psi into the solenoid. Obviously I have no pressure regulation, but I have

30 psi. I know I don't have overpressure at the time the sprinklers are operating because the heads don't pop completely up if I reduce the pressure any more. Therefore, I think you still can help me -- in spite of my goofy regulator..

What would cause the coverage gaps about 3 ft from the sprinkler heads? I have 12 and 15 foot nozzles? The spray looks normal.

[Ulrich M. Reich]

Ideally what you are trying to do is to get an even spray from one head to the next. If you have too many heads on a zone, too much water going through the nozzles, your pressure may drop just enough not to reach the next head to it. A 15' half circle nozzle uses about 1.8 gallons per minute at 30 psi. (12' nozzles do about 1.3 gal. per minute at 30 psi) If you have 22 gallons per minute available you should use a max of 10 - 11 heads with 15' nozzles, and as many as 15 - 16 heads.. Anything above that and you suffer the consequences of inadequate coverage. One thing you may be able to do is make sure that all of the nozzles are the same size, all 12' nozzles. Then there are pressure compensating screens available that will limit the amount of water coming through and increasing the pressure a little bit. Another thing to keep in mind is that not all 3/4" pipe is made alike. Schedule 40 is thicker walled than class 200. Class 200 is a thinner walled pipe and as such will allow a little bit more water to come through allowing for more heads. Finally, depending on the shape and the size of the lawn areas you may be able to change from a spray head to a stream rotor. I have successfully used Rainbird 3500 series rotors. At 25 psi and a nozzle size of 2.0 you only use 1.4 gallons per minute, thus your pressure increases by using fewer heads. The down turn is that your precipitation rate also drops dramatically. To get the same amount of water to cover the larger area you will need to water longer. In general the sprinklers will run from 1/2 to

3/4 hour per watering. But with your trusty tuna can you can dial in the watering time pretty accurately.

Good luck

"G Burton" wrote in message news:o [e-mail]...

[G Burton]

Thanks!

You made some good suggestions.

I have some piping that is class 200 (or 100), and I have had horrible experience with it breaking every time I touch it with a shovel. I replace it with class 40 whenever I can.

I don't think I can convert to the rotors, but I will look into it. It wouldn't make sense unless I could do my whole lawn that way, and I'm not sure the shape of the lawn will permit that.

I will also look into the pressure-reducing screens, and reduce the spray diameter wherever I can.

You gave me some good homework, but I'm sure there is a solution in it.

[Tom Jaszewski]

Acts of creation are ordinarily reserved for gods and poets. To plant a pine, one need only own a shovel.

-- Aldo Leopold

[G Burton]

That lowers the level!

I don't think the rotors will work for me, but I disagree that Ulrich is an idiot. I intend to check out all his ideas, and I appreciate his help very much.

I'm sorry I bothered you. I hope you find peace.

[Ulrich M. Reich]

Since you seem to the know it all, but trust me do not to have all of the answers. Too many narrow minded people have to resort to foul language to make their point, and it was only a suggestion, not a solution. You obviously don't use rotors otherwise you would know a little bit more about their applications. While I agree, they are not the head of choice for every application, but they do work and if their are faults built into the system, they can overcome some of those problems.

successfully

spot....sorry

pine, one need only own a shovel.

[Ulrich M. Reich]

Thanks Gary,

successfully