SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

You might be too far north to be able to consider the ground free from the danger of freezing solid, which is a shame, since that would exclude you from what could be an elegant design solution.

Just so you know, a professional install over the acre-plus of that airstrip could be an expense of ten thousand dollars or more. From the viewpoint of the do-it-yourself homeowner, it becomes something of a 'pick your poison' situation, as to how you get a larger supply of water to the runway area, and furthermore, how you allocate the water.

Offhand, I would state that unless you can get at least 20 gallons per minute at 60-70 psi from your supply, you are going to have a tough time covering that acre-plus, especially if the soil is sandy. If you had unlimited time and expense to make use of the existing 6.6 gpm supply, it would mean a double-row of rotor heads, with a head count of at least 70 and a zone count of at least 35.

The more elegant solution involves the sort of heads used on athletic fields and golf courses. Compared to residential sprinkler heads, these 'pro' heads are extremely expensive, but they have the advantage of longer throw, so less of them are required, and some of them have a built-in control valve that opens and closes by way of water pressure applied by a tube. These "hydraulic valve-in-head" sprinklers save the expense of valve wiring, as well as providing protection against lightning strikes, but the control tubing is generally not considered desirable for use where it can freeze.

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To extend the number-crunching, a design could be dumbed down to its simplest form, as a line of full-circle heads down the middle of the runway. Heads spraying 30-foot radii can be spaced 30 feet apart and they will cover a strip just over 50 feet wide, with a minimum head count of 39, in a minimum of 13 zones. With the controller at the house, over 1000 feet from the furthest valve, the wiring will be still be a significant investment.

I'm in the southeastern portion of TN in a rural area, about half way between Nashville and Chattanooga. It still gets pretty chilly in the dead of winter, so freezing is of a slight concern. Codes wise...I haven't checked on anything with this but building codes wise, there's not a whole lot of it around here.

Where is your location, by the way? I ask because of plumbing code variations and freezing concerns.

The power source is almost at the same location as where I have the spigot marked.

There is actually a well (hand dug) only about 10 feet from where the spigot is marked also. It is 30 feet deep and used to feed the house back in the day. I don't have a clue on what the capacity or anything is in it, but we sometimes use a small submersible pump in the summer to water a garden and have never ran out yet. That was using a pretty low flow rate, so probably not a good indicator of what could come out.

Also, from only being 30 feet deep, it probably wouldn't take much to drill another one out much closer to the runway.

You might want to look into drilling a well for this project (and maybe for supplying the house, too)

The water main crossing the area getting watered is going to be your best bet at doing the job in the optimal "big water" style. You might even be able to handle it with a single line of big heads off one side of the runway. Big Water means more expensive individual components, but less of them, so overall reliability increases.

What's your closest power source to the runway?

Sorry for taking so long to get back on here. I was able to get my flow rate and its right at 400 GPH, or 6.66 GPM.
There is actually a 6 inch water line running perpendicular across/through the strip right on the bottom side of the dried up pond in the previous photo. This would probably be my best bet but was trying to shy away from getting another meter installed, but that's not a showstopper.

Thanks again for your help so far in this!

I would be recommending against putting anything in the runway itself.

Strictly for cost reasons, along with improving system reliability, there are good reasons to look at installing a line of heads on either side of the runway. First, is that you can easily cover the 50-foot width with standard residential heads on either side spraying a 35 foot radius.
Second, is that with two mainlines on either side of the runway, the flow can be split between the two lines, making for less flow in each mainline, and lower flow will allow for smaller zone valves (two standard zone valves cost less than one larger-size valve) and also reduce the effect of water hammer, which is an important factor when there are many hundreds of feet between your source and your zone valves.

Another cost factor will be the control wire to the zone valves. Because of the distances involved, standard 18-gauge irrigation cable may have too much resistance for operating multiple zone valves at the distances involved. One can always increase the wire size, like using a single 14-gauge wire for a system common, but this may be a project that could be more economically done with what is known as "2-wire" control. That spends money on the controller and decoder modules, rather on lots and lots of copper wire.

This looks to be the work of several zones. If I were tasked to do this job, I might have a second water meter installed just as close as I could locate it to the tap on the water main, so that I could pull at least 30 gpm, and from there increase the pipe size to 2 inch.

This is no little job to be dashed off as a bargain with ho-hum equipment and installation. You are watering over an acre, with the most distant head close to a third of a mile from the source.

I haven't been able to get the flow numbers yet, as I won't be there to measure until Saturday or so. It's on city water. I know the meter is 3/4, but not sure about the main line. I think the main is only an inch, but could be wrong.

I wouldn't be against placing the sprinkler heads in the middle also if they were somewhat tough and flush with the ground. It's not like it's going to see that many operations on a frequent basis anyway. The weight of the tire is only around 300 lbs and would cross over in a split secondif they were ever ran over.

Thanks for the help!

Pressure is meaningless without flow. High pressure is good, and it gives you options.

To completely cover the 50-foot wide strip from heads off of one side puts you into the realm of big expensive athletic-field/golf-course heads, and you need a great deal of flow to make those work.

Is this on city water? If so, what are the sizes of the main and water meter?