As most of you may have seen, the Coors Events Center has been under construction for the new Basketball/Volleyball Practice Facility. Along with construction always comes a little bit of destruction of existing landscape. This is not always a bad thing, by consistently working to upgrade buildings and infrastructure on campus we help to prevent becoming stagnant and work towards continuous imporovement. At a previous employer I learned a saying that seems to fit perfectly, " You have to crack some eggs to make an omelet." I constantly remind myself of this during construction projects.
Many other locations where landscape is installed there tends to not be much in the way of constant construction or change. When they designed the irrigation system 20 years ago they had no idea where buildings would be constructed or how funding would ultimately change those master plan ideas. Sometimes with those changes come major impacts to the irrigation delivery system. I consider major portions of the delivery system to be 4" mainlines and larger.
Recently during the later stages of the practice facility design it was determined that there needed to be an area which would allow large semi-trucks to be able to back into the new loading dock. A relocation of the existing 6" mainline would have to be undertaken.
In the above picture you will see the 6" PVC mainline. Since this is a change in direction there needs to be concrete poured behind it to prevent it from moving. This is known as a "kicker" and must be poured up against virgin soil to make sure that it stays in place. The "kicker" is technically called a thrust block and is used to handle a phenomenon called "Water Hammer." The best way to describe what water hammer is to talk about the banging noises you may hear in old houses as you quickly shut of the faucet. The hammer is actually the force of the water rapidly stopping, because as with many things, once the water is in motion there is a certain amount of force behind it in motion. To have it stopped suddenly or change direction suddenly it will tend to apply forces which must be counteracted. In a home situation this hammer is normally not of sufficient force to cause a break in the pipe. However with large pipes the forces are easily great enough to cause breaks in the pipe.
In this picture you can see the actual pipe fitting prior to the plastic and concrete being applied. Also in this picture you will notice some control wires. These are the wires that run from the irrigation clock to the individual zones and allows for the operation. Relocating the mainline itself is not too much of a problem, it is pretty straight forward.
However, the main issue comes with control wires. In the ground the control wires are just that, wires. But each individual wire goes to a station and is associated with a designated station in the controller and also the Network 8000 computer. The real challenge comes during the operation of the stations from the computer, each station has its own identity in the Network 8000 and along with that identity is the amount of heads on that station, the type of heads, the amount of water those heads put out, etc. As with any computer system it is only as good as the information you put in it, so if a station is not put back in the correct sequence it may run that station thinking it is a rotor zone but is incorrectly hooked to a pop up zone. Pop up zones generally run anywhere from 5-10 minutes during a cycle where as rotors can run up to 45 minutes, obviously there are going to be some serious flooding concerns if those stations end up running for that long.
We work extremely hard with contractors to make sure they understand this risk and take all necessary measures to iensure that there are not mistakes during this portion of the job. Of course once things are buried it becomes extrememly difficult to make repairs to the wire and thus we do extensive testing before the pipe is buried to make 100% sure everything is correct.