Gathering information is the first step for most projects and it is one of the most important steps when designing both sprinkler and drip irrigation systems. A mistake at this point in the process will affect everything else, so accuracy and care are important. Although the references here are to a residential yard, the principles apply equally well to other areas. Here are a few tips for getting started.
- Use a measuring tape or other accurate measuring device. Many irrigation system problems are traced back to inaccurate measurement of the area to be irrigated. Go ahead and round off numbers to the nearest foot. But keep in mind that a minor deviation of a couple of feet can result in dry spots! “Pacing off” the distance using your stride almost always results in errors. If you are being that sloppy at this point, chances are additional sloppiness later on in the design and installation will compound those errors. Remember that old shop class advise: “measure twice cut once?” You thinking having to replace a piece of wood cut the wrong length is bad? Try digging trenches twice!!
- Draw the area to be irrigated to scale on a piece of graph paper as you measure it. Use a scale of 1 square = 1 foot, or 1 square = 5 feet if needed. Drawing as you go allows you to quickly catch errors. For instance, say you measure the perimeter of the yard. Eventually you get back to the point where you started, but you find that the lines drawn on your paper don’t meet like they should! Now you know there is an error in one of the measurements, and you can go back and find it quickly, while it’s all still fresh in your mind.
- If there is a building adjoining the irrigated area, start by measuring the building’s perimeter. Most buildings are built with square corners and straight sides, which gives you a good, accurate base for the rest of your measurements.
- Use the straight sides of the building as a guide for establishing the perimeter of the area to be irrigated. Measure in a straight line the distance from each corner of the building to the edge of the irrigated area or property. (Locations to measure are shown in red on the sample drawing below.) Use the straight edge of the building to line up your measurements. Now you can draw in the property lines on your graph paper using these measurements. Double check everything by measuring the length of each property line. It should match exactly what you have drawn. Don’t be surprised if you find that an area you thought was “rectangular” is actually lopsided like the one in the sample drawing! Most pieces of property aren’t perfect rectangles.
- The final step is to draw in the other items that are present in the area. For example, if this is your house, you would need to show the edges of lawns, tree locations, the location of your pool house, the servant’s quarters, etc. (Okay, I realize most people with servant’s quarters don’t design their own irrigation systems.) With the building and property lines drawn it is easy to use the grid on your graph paper to establish the locations of these items.
Measuring Changes in Elevation
Changes in elevation are also easy to measure. Simply get a yard, meter stick, or long pole. If using a pole, make marks on it one foot or 10 cm apart, starting at the bottom. You will need a helper and some of those little wire flags used to mark sprinkler head locations. Now you need a long carpenters level, preferably one about a yard or meter long. Place your pole at the lowest part of the yard. Now place your level along the side of the pole, at the same level as one of the marks , such as 2 feet. Adjust the level so is level. Put your eye at one end and look across the top of the level. Now have your assistant place a flag in the ground at the spot you see aligned with the end of the level. Repeat with different levels and locations in the yard. When you are done you will have a row of flags at the points that are 2 feet above the place where you put the pole.
Measure Your Water Supply
Now it’s time to measure your water supply. Measure water? Sure! Water flow is measured in gallons per minute (GPM) and water pressure is measured in pounds per square inch (PSI).. (Okay, in most of the world the standard measurement is liters per second or cubic meters and pressure is in bars.) But hold on, don’t go grab your bucket yet! In most cases there’s no need to get wet. We have better ways to get this information. The method depends on where you get your water from.
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City Slicker Water. It’s like, you know, the water just gets here, like maybe in a really, really, big pipe, from somewhere else. You know? Like, I just get a bill each month and I pay for it, so, like duh, how would I know how it gets here? It’s like, I think my whole city gets their water from the same big pipe too. So like, I’m bored by all this… Let’s go to the mall!
Country Bumpkin Water. You pump yer own water, partner. It may come from a well or maybe a pond or the creek. It’s the rural lifestyle, self sufficient. Anyhow, key thing here is you use a pump to git it done. You may share a pump with a few of the neighbor’s or kin folk with places nearby. Yee ha!
Backwoods Water. Doggonit, that there water ain’t comin’ from none of them fancy contraptions. It done flows from a tank, a crick, or pond up on da hill without no help from nutin’ but gravity. Now get yer butt off ma porch b’for I fill it with a coupler barrels o’ rock salt!
(Ha ha! My spell checker is sure unhappy about those paragraphs above!)
This article is part of the Sprinkler Design Tutorial Series
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