When the manufacturing of plastic drainage tile began in the late 1960s, the process was a little different than today’s standards. One of the primary differences was the method used to select and test raw materials. Pipe made with “virgin” resin was the only product available at the time. The tightly specified blends of reprocessed materials that we have today were not yet available. However, the industry jumped on the development of plastic tile because of the light weight design and ease of use compared to clay or cement tile that had to be hand laid.
Fast forward to 2015: You will be hard pressed to find a clay drain tile manufacturer and only one tubing manufacturer holds onto the notion that plastic drainage tile has to be made out of strictly virgin resin. Clay is gone not because of quality – there is A LOT of clay tile still working hard. It’s gone because it’s more difficult and costly to install. And now the vast majority of drainage tile for ag use is made from blends of reprocessed materials that meet the strict cell classifications of ASTM industry standards instead of virgin resin. Today’s industry standards and methods of testing and controlling raw materials allow for the production of a more consistent drainage tile – one that provides a longer service life than the old, widely varying virgin resin blends.
There are three major evolutions that have taken place with drainage systems, and they all boil down to one thing: Cost.
In a recent article, Good Isn’t Good Enough, we talked about splitting lateral spacings on outdated drainage systems to increase yield. During retrofit installations, we evaluate the condition of the existing materials in the ground. When installing new drainage systems or conducting a retrofit, we often run into older plastic drainage tile that was installed as part of an NRCS project or perhaps a random drainage effort. The careful evaluation of existing plastic needs to take place before it is used in a new system.
Here are some of the things we look for when evaluating existing plastic tile:
- Cracking: Some early plastic drainage tile can exhibit signs of environmental stress cracking. Environmental stress cracks may take place along manufactured seams, and in some cases, may become present around the circumference of the pipe.
- Installation Method: In some cases, installation methods may have been closer to a flat bottom trench rather than properly supporting the lower 1/3 of the pipe. Lack of proper support may have caused “ovaling” of the pipe. If this is the case, it may be necessary to replace this product with new.
- Proper Material Size: Obviously, if a new plan calls for an 8” pipe to achieve ½” drainage coefficient and the existing line is only 6”, a new line must be installed.