What you don't know about your synthetic turf project's base construction could cost you

Charlie Cook, senior vice president of operations, General Sports Turf Systems.

Hopefully, the installation of your new outdoor synthetic turf athletic field will be another pretty face. If it’s not, you know immediately you’ve got problems. But if you don’t have a properly constructed base and drainage system beneath it, your problems are going to be much worse than turf deep — and far more costly.

I can tell you that 15% of all synthetic fields have base failures due to settling and erosion of an improperly designed base. The turf mirrors what the base provides. That’s why it’s extremely important to hire experienced professionals who not only know what they’re doing, but will stand behind what they do.

Properly preparing the base takes much longer than actually laying the turf and, when done properly, is likely to far exceed the life of the actual turf.

The first step a conscientious turf company will do is review an existing or take a new topographical survey. The results will reveal a range of characteristics of your site including elements such as soil composition, utility locations and precise field elevations.

Then an infrastructure study will be conducted to evaluate the existing base conditions and load calculations, factoring in the average amounts of rainfall and climate conditions. At the same time, geotechnical soil borings will provide information on the existing soil layers of aggregates, topsoil, silts, clay and other composites that will yield an aggregate drainage profile. Civil engineers can then determine how thick the base and finish stone should be to determine if there should be additional excavation of native soils.

Geotextile fabric is the next consideration, specifically engineered to allow exact amounts of water to either seep into the subgrade or not permeate at all, depending upon the type of existing soil. At this point, make sure your existing storm drains are cleaned or jet rodded to ensure the new system will flow freely into the existing storm structures.

Next, a sieve analysis is conducted to gauge the gradation of aggregate. Mixtures of stone sizes, compacted by gradient levels, are critical to stabilize the base and also to provide the characteristics for adequate drainage. Improper compaction of the stone base can cause shifts and soft spots, both very expensive mistakes. Costs of preparation to this stage are likely to run about $5,000. That’s a small percentage of the total project, but is critically important to your investment.

Field slope is another important factor that can mean the difference between good drainage, as well as good looks, and an unsightly and potentially dangerous “corduroy” field. Many architects will allow a one-quarter-in. slope tolerance within a 10-ft. grid. While this is acceptable in the industry, it’s possible that this standard can result in 6 in. to 8 in. variances over the length of the field. I recommend instead that you choose a contractor who is able and qualified to use GPS-guided laser technology to measure a tolerance of no more than one-quarter-in. over the entire length of the field to ensure a completely flat, unwavering surface.

Finally, plan to have your field base tested by an independent testing agency for compaction, density and permeation. Don’t hesitate to check your turf company’s work. This is the time to discover if any alterations need to be made, not later. Competent turf companies welcome and expect this.

Field owners and managers new to the process should definitely check references and look at the turf company’s track record of successful installations, paying particular attention to the qualifications and experience of the architects, engineers and site-work contractors. Know your turf company’s standards well before you invest.

Consider carefully. The success, longevity and beauty of synthetic turf are never only turf deep.