I Can Dig It - Welcome

I Can Dig It was Originally Posted on February 10, 2009 by lavarock

I found a guy who has agreed to trench my farm. Along the new driveway, I need a trench to hold the water line which will run up the property from the pump at the bottom to the three tanks at the top. He will arrive about 10am today with the equipment. I also need over 1,000 feet of PVC to lay in the trench to hold the valve control wires. The pipe does double duty and the valves will determine which particular function the pipe will have at any particular time. Part of the time, water is pumped up to fill the upper tanks. Later, the tanks are disconnected from the flow and the pump supplies water to irrigate the upper 2 acres. This is because the upper tanks are too close in altitude to the upper tanks to develop any kind of pressure. However, the upper tanks can supply enough water pressure to irrigate the bottom 3 acres. Thus, part of the time the pump is turned off, the tank drain pipes are connected to same pipe going up the property, and the water flows back down to irrigate the bottom 3 acres. The top 2 acres must be disconnected at that time.

I am also contracting with some local workers to lay out the new 1500 holes so the guy can punch (drill) them. The guy punching the holes wants to lay them out too, and I’m sure would love the extra money, but his cost was a lot higher than the workers and they can send 3 or 4 people here to quickly lay out the grid; a lot faster than the guy and I can and right now, time is of the essence.

One thing that a computer programming background helped me on the farm, was creating a truth table of which valves need to be on and off at what times. The valves are a lot like transistors in that they are either on or off. If a valve is normally closed (like for a sprinkler system) then putting a voltage across the wires of the valve makes it open and water flows through it. Remove the voltage and the valve closes again, shutting off the water. I found that I only needed a few wires and a few positions of a set of switches to make things work. In my design, some valves need to be open while other valves need to be closed. Normally that would take a wire to each set. However, if I find that some valves are always open when the others are always closed, I can use a mix of normally open valves and normally closed vales. When I supply a voltage on the wire, the normally open valves will close and the normally closed valves will open. Naturally you want the system designed that if the electricity fails, the valves go to the position that does the least damage, such as closing the correct valves so that all of your water does not drain out and flood things. You may notice this same type of failsafe in everyday use. Take traffic lights for example. If the controller fails but there is still electricity, the main road gets a flashing yellow light while the smaller cross street gets a flashing red light.

I need to finalize the truth table and buy the wires. I also need to hire someone to fuse the many pieces of pipe together so it can be laid in the trench. The PVC and with my wires inside will sit neat the water pipe in the trench. In about 5 places the PVC has to exit the trench and be connected to a wiring strip so I can attach it to the valves. Valves will control each acre, thus a connection each location. The PVC is an added cost and I have been asked why use it? Why not just bury outdoor wire? That was asked by someone who has never had to dig up a wire that has shorted. In a PVC pipe wires can be added or removed with ease.

I need to go cut some grass and I’ll start taking more photos, soon to be displayed on the farm page at http://ItsKona.Com, along with my Pele’s Passion Coffee.