Yesterday morning was the Drip Irrigation Demonstration at Linda and Kurtis Colonna's lovely home in Manchaca. The plan was to install two irrigation systems, one at what I am calling the "Tropical Hook," and the other at the swale and berm they built at the corner of the yard where the driveway meets the street, which I'm calling the "Angle Berm".
I think this was my favorite Blitz so far because we actually had a workshop before implementing the plan, and I got to hear explanations about various permie features at their home. Also, this is the first Blitz that I actually was around, and not playing go-fer, while people were mingling, so I had a wonderful chance to talk to several people. I'm not even going to talk about the fabulous lunch afterward because I haven't had my breakfast yet.
We had a great introductory lecture by Kirby and Zach about Permaculture in general, and about drip irrigation specifics. We learned about all of the components of the drip irrigation system, and the purposes of each piece.
1. At the faucet, make sure there is an anti siphon/vacuum breaker component to prevent backflow from the irrigation system entering into the water source. Most modern plumbing systems have these already installed between the interior house water lines and the exterior faucets, but if you live in an older home, as I do, you may have to add this component yourself.
2. Next, you want a valve a manifold. We used a simple brass Y valve. The valve for the irrigation system must always be open, with the water always turned on. You can use the remaining valve for hand watering, bucket filling, etc, and this valve should be closed most of the time.
3. After the Y-valve, place the timer. It can easily withstand the high pressure of the water as it is designed to do.
4. Most drip irrigation systems operate at 25-35 PSI, so you need to install a pressure regulator immediately after the timer.
In general, for sandy soil, you want higher flow rate emitters spaced more closely together because the water tends to be absorbed quickly and deeply; for clay, you want lower flow rate emitters spaced further apart because the water tends to pool on the surface.
To determine exactly what you need in the way of emitters and length of irrigation lines, and how long to run the irrigation system, run a simple test. After you install the pressure regulator, time how long it takes to fill a 5-gallon bucket. Then use this formula:
60 minutes (per hour) * x gallons per minute to fill the bucket = y gallons per hour in the line
5. Next comes the filter to keep minerals and other particles from clogging up the system. Check and clean the filter regularly.
6. The faucet connects to a ¾-inch standard hose. Drip irrigation black feeder lines, which are solid plastic tubes, are typically ½-inch. After the filter, you need a ¾-inch to ½-inch reducer component.
7. Now you place the ½-inch black feeder line which runs from the faucet manifold to the site you are planning to irrigate. Before installing it, you should run water through it to both clean it out and to determine if there are any holes that need repairing.
8. At the head of the irrigation site, you need a T-connector. This allows you to split the water between two or more brown lines, which are ½-inch lines with pre-installed perforations at specific intervals. We used brown line that had 1 GPH (gallon per hour) emitters spaced at 1-foot intervals.
9. After the T-connector, cut small pieces of black line to create the space between the brown lines.
10. Use T- and L- connectors to create this manifold. Make it pretty, and measure the pieces to be the same length.
11. Measure the brown lines to length, and connect them to the black line manifold. Before installing them, again, you should run water through them to both clean it out and to determine if there are any holes that need repairing. If you find a hole. Cut the line, and reconnect them with a simple pressure coupling.
12. Depending on what type of planting is being irrigated, you can use one of two methods to finish off the brown lines.
a. If you are working with a perennial bed that will not be worked in the future, you can create a black line manifold to connect the ends of the brown lines. This will keep the pressure more constant across the various brown lines. The down side of this is that it is difficult to clean out the lines and almost impossible to move them out of the way to work the soil in the furute.
b. However, if you think you may want to work the bed or berm in the future, consider folding over the brown line and using a figure-8 connector to cap off the line. This makes it easy to clean out the lines at the end of the season, and to move the lines out of the way when you want to work the soil. CAVEAT: don't use wire to cap off the ends; it corrodes, and can even damage the plastic lines over time.
13. After installing the irrigation lines, cover them with mulch to reduce evaporation, and retain more moisture in the soil.
Two high-end brands of irrigation components are: Submatic and Netafim. Zach likes Netafim, and gets it at greatly reduced prices at http://www.irrigationdirect.com/.
After the lecture, we traipsed out to the "Tropical Hook," where Kurtis and Linda have designed a structure to catch the water coming off of the roof where the porch meets the main house. Kurtis explained the purpose and design. Before the Hook, rainwater collected at the southeast corner of their house, and then ran under the gate, crossed the front yard, and left the property at the entrance to the driveway at the street. Earlier this year, Linda designed the hook, and they built it.
The Hook, essentially a specialized berm, extends from the corner of the house toward the south fence, and loops back toward the house. The interior of the hook is a 4-foot pit that is a compost heap. Kurtis said that it's about 40% coffee grounds that Linda, as a member of the Compost Coalition, picks up weekly. Overflow is designed to follow the original path of the water to the low spot on the property, but it is caught there with a 90° berm and swale.
The Hook is planted with tropical trees Kurtis, as an employee, got for free after the Central Market's Brazil Week extravaganza early this spring. There are 3 cultivars of bananas, mangos, a Haas avocado, and two other trees with which I am completely unfamiliar. They have sweet potato growing as a ground cover over the berm. One of my favorite features about this system is the compost heap is right in the middle of the Banana circle, so it will keep the trees warm in the winter, and you don't have to move much, if at all, to compost anything that is pruned off of the trees. Linda was pruning the banana trees as we listened to Kurtis, and she just tossed the clippings into the pit. Marvelously efficient!
Next, we went out to the "Angle Berm," the lowest spot on the property, and where rainwater runoff once left the property. It was originally planted earlier this year with a small plum orchard, but a few trees didn’t make it through the summer. One was replaced with a peach tree. There is a beautiful Golden Leadball, Leucaena retusa, farmer's tree. There were asparagus, tomato, and various other plantings, as well.
Since the Tropical Hook and Angle Berms were built, Kurtis says the rainwater runoff now stays on the property. I like to think of them as catchers' mitts at two bases on the Colonna property.
I am hoping that the irrigation systems we installed on these two berms will allow the plantings to flourish in our hellish summer heat.
Zach showed us how to connect all of the various parts of the drip irrigation system manifold, how to check the lines for leaks and obstructions, how to build the black line "valve" system that connects the brown lines to the water line, where to run the brown lines, and how close together to install them. He was using reclaimed brown line that the City of San Marcos has dumped by the river after digging up an irrigation system at a location that I did not catch. So, not only did we learn how to install a new system, but how to repair one! I personally got to build the second drip irrigation manifold.