Hi Lou,

Here is an interesting idea that may work for you without knowing the flow you are dealing with.

Place cups with as vertical sides as possible all around the park. As many as you want to deal with. Locate them on a map. Since this area is irrigated with impulse/rotary sprinklers attach a spike to the bottom to anchor them in place or some form of anchoring system. Turn on the sprinklers for a specified time and measure the depth of each plotted cup. Do this as many time as you like over a period of time. You can do zones separately if you like. The cups do not have to be placed in the same spot each time. Just place the new locations on the map. This map will give you patterns of equal watering intensity(in/hr). It will show over and under watered areas. If you get a copy of the irrigation plans for the park. You can check designed flow and timing needed to provide 1" inch per week. This is an audit of what is going on irrigation wise at the park. Also record runoff from the park and where. Soil porosity is a big part of scheduling frequency of irrigation. Do they aerate and mow the park regularly? This an important part of allowing the irrigation to work properly and get to the grass roots instead of running off.

GL Aloha

Generally speaking, a well designed system comprised of rotor heads will apply ~1/4-1/3" of water in 30 mins. but it all depends on the design and the nozzle size. As Lehua suggested, do a simple water audit to determine what the precip rate is. Remember that precip rates will vary from zone to zone even with the same type of heads, so check each area covered by the respective zones.
Also as previously recommenended, see how long it takes to achieve soil saturation/runoff. Any time spent watering after saturation is wasted water unless you implement a cycle/soak method of scheduling. Soil will largely dictate how long saturation takes.

All Wet

A cheap and easy to determine how deep a given irrigation has penetrated the soils is with a simple probe. My probe is a piece of 3/8" x 3 1/2' long steel rod with a 1/2" ball welded on one end and a t-handle welded on the other. To use it, simply push it into the soil and pay attention to the force you exert on it as it goes in. When the ground is very dry it should require noticably more force to push it down to the bottom of the root zone. When the ground is saturated after an irrigation it should go in much easier until you reach the bottom of the saturated zone at which time the resistance should noticeably increase where the water hasn't made it yet. I you go probing and notice the soil wet way beyond the root zone on a regular basis, they may well be overdoing it DEPENDING ON THE SOIL AND IRRIGATION WATER QUALITY. Just had to put in that disclaimer. A pickier way of doing it would be to use a soil sampling probe and looking at the cores when you pull them out. BTW, I don't think prodding would work on sandy soils, probing would.

Probing and watching runoff is the way to go since you don't control the system and record the data since it is for a bureaucratic organization that might be resistive to change or actually not paying attention but wants to appear like they do(CTA). JMHO. Aloha

There really isn't any good way to know without doing direct measurements similar to what lehua13 has suggested.

all_wet's estimation of 1/2" per hour is a rough estimation given the type of equipment you have. It gives you a ball-park figure to start with, and lets you know that you are NOT going to get 1" of water in only 20 minutes. Beyond that, the precipitation rate depends upon placement of the heads, types of heads being used, water pressure at the heads (much differant that what the water pressure started at before flowing through valves and pipe).

Thank you. I've used screwdriver (8inches long) in the past but wasn't sure how effective it was. The ground is clay so obviously, slowly soaking over period of time is required. I don't know why 3 times a week for 20 minutes is so prevalent everywhere. I can understand if you're trying to establish new grass but it does absolutely nothing for established lawn and trees except growing million of weeds. I did ask for access to the system to find out how long it takes to fill up 1 inch of tuna cans but never heard back from HOA. I had recommended bi-monthly of deep watering at 2 inches of water to thoroughly saturate 12 inches of ground to benefit trees and bermuda grass (can grow roots foot deep). It may be a lost cause anyway.

Hi Lou,

If nothing else talk to them about aerating the soil and placing a organic sand mix right after. This will start improving the water penetration and condition of the soil, but they may be resistive because of $$$. If the soil is improved you need less water in the long run with less runoff. After heavy use in the park the soil characteristic changes for the worst without aerating. This is what they do for golf courses. GL and Aloha.