A field’s grade is its backbone, and a weakness in any one part of the system can cause the whole thing to fail. A failure that can leave you with flooding, puddling, washouts, unhealthy turf, and unsafe playing conditions. So whether the failure is severe enough to prevent field use or just inhibits play the bottom line is revenue loss from lost games and costs for repair.
If you’ve played golf you’re acutely aware of how the grade of a green affects the play of the ball. Tremendous time and effort goes into the design and construction of the best greens in the country where the architects must balance the play of the game with the needs of the turf. Placing the hill in location “A” may make a better game for the players but if it moves water too quickly from the green (surface or subsurface) the grass will need extra irrigation to stay alive. Indeed, placing a dip in location “B” can make the putt more challenging but if it also inhibits excess water flow then the green may be out of commission during much of the season.
The purpose of the grade on an athletic field is to move excess water as quickly and efficiently from the field of play as possible without also causing undue damage in the process. That is, we want to provide enough of a grade to move water without moving so quickly that parts of the field are washed out with it. Sports fields are not nearly as sensitive as golf greens, but they are much more sensitive than other build structures.
Good Grade versus Poor Grade
The Subgrade and Water Movement
A good grade starts below the surface. Whether you’re installing a high performance, sand-based field or working with natural soil it is important that the grade is consistent throughout the surface, especially the infield. When done properly, water not only moves smoothly across the surface grade, but that which filters into the soil will drain and move evenly as well. However, if the subgrade is hastily and mistakenly installed, water movement is uneven, some areas will retain excess water (causing puddling and flooding) while others will dry too quickly even following the strongest of precipitation evens (unhealthy for turf, dangerous for infields).
Other Subgrade Issues
Another subgrade problem occurs with winter freezing and the freeze-thaw cycles of the spring and fall. This can cause, cracking, heaving and sink holes in the field causing extremely dangerous conditions requiring immediate repair. An experienced contractor will have the base soil professionally tested and will work with you to provide the proper solutions for your field and budget.
The subgrade also affects sub-soil structures such as irrigation and installed drainage. The final shape of the subgrade is not critical for irrigation functionality, but any heaving or sink hole development around irrigation lines can be quite problematic. Installed drainage is quickly and easily disrupted by subgrade issues. If the proper pitch of the drain lines is inaccurate the water will not be able to exit the playing surface and will back up into the field.
The Final or Surface Grade
Many owners unwittingly hire road crews to grade their new fields and quickly learn that as flat as roads may seem when we’re driving on them in reality they undulate quite a bit. Having such undulations on a sports field is disruptive to water flow, turfgrass health, the play of the game, and of course is can be very dangerous for the players themselves.
The ability to use a laser grader (or GPS grading technology) on its own is not a sufficient qualification for the field installer. It takes a very skilled technician to correctly adjust the cutting blade of the grader at the right times and to do so at the approporiate speed. Tolerances for any sports field fall within 1/4″ and in order to provide such precision it takes extensive experience not only on the machinery but also on the fields themselves to learn the feel of a properly finished athletic grade.
Speaking of GPS Grading
Though many different applications have been developed for and using GPS technologies it has been only recently that it has achieved the appropriate precision for use in athletic fields. Because we know just how important the grade of the field is to its performance we have recently purchased our own GPS driven grading tools!!
GPS technology will provide H&K with the means to more quickly and accurately asses sites for development and measure the magnitude of grade issues on existing surfaces. We’ll also be able to generate auto CAD based maps which will aid us before and during the grading process. Upon completion of the job we’ll deliver to you the most accurate “as-builts” possible. We can even include irrigation, drain lines and electric wiring.