Drainage Solutions inModern Sports Field Applicationspresented by

Hank BellSales Manager/Airfield Systems, LLC.Edmond, OK

USTC&TBATechnical Meeting and Trade ShowDecember 3-7, 2004

With the dramatic rise in annual sports field construction, designers and builders are faced with a myriad of challenges.

The following all factor into the final design of a project:

1. The specific use or uses of the site.2. The regional climate.3. The availability and cost of materials.4. The financial resources available.5. The time restraints or requirements.

As the health, safety and usability of a field is directly related to the efficiency of the drainage system, understanding the available options is critical to success.

There are basically three distinct methods used in sports field drainage:

1. Surface Drainage2. Gravel Drainage3. Synthetic Drainage

Each of these systems have advantages and disadvantages.

Surface Drainage is the simplest and one of the most common methods of drainage. It is typically built with an eighteen to twenty-four inch crown and as the name suggests, water is drained across the surface of the field.

The main advantages and disadvantages of Surface Drainage are:

Advantages1. This is the least expensive method and may be the only method

some owners can afford.

Disadvantages1. Poor subsurface drainage results in a saturated field with standing

water.2. The health of natural grass fields can be compromised.3. The rubber infill of an artificial field will migrate from the crown of

the field.4. Safety concerns of playing on a saturated field.5. Games and practices are cancelled due to unfit field conditions.6. Lost revenue due to the cancellation of games or events.

Subsurface Gravel Drainage is far superior to surface drainage due to the efficiency of transferring water through the surface rather than across it. It is the most widely applied and accepted sports field drainage method used today, however that may change in the very near future.

Gravel Drainage is usually accomplished by precision grading the field cavity with a one percent slope from the center of the field to the perimeter. The cavity is then trenched in a herringbone design for a french drain piping system. The entire field is then covered with four to six inches of precision graded, washed gravel. Next, another layer (one to two inches) of smaller gravel is installed and precision graded.

In artificial turf applications the turf is installed directly on top of the smaller gravel.

In natural grass applications a twelve inch sand root-zone mix is installed on top of the smaller gravel and then precision graded. The field is then sodded or seeded.

The main advantages and disadvantages of Gravel Drainage are:

Advantages1. Drains much better than surface drainage.2. Gravel is readily available in most regions.3. Gravel can be cheaper than synthetic drainage in some areas.4. Most sports field contractors are familiar with handling gravel.

Disadvantages1. Quality gravel is not always available at an affordable price.2. Gravel drainage beds can settle and shift over time causing an uneven

playing surface. This can cause warranty issues for artificial turf applications.

3. New gravel drainage blankets do not drain as well as some synthetic applications and rain-outs still frequently occur due to sheer rain volume.

4. The installation process of the gravel drainage blanket uses heavy equipment and takes several weeks to complete.

5. Over time most gravel blankets become clogged and must be replaced.6. Until a clogged gravel system is replaced, all the disadvantages of Surface

Drainage will apply.

Synthetic Drainage is the newest form of subsurface drainage. It comprises a large variety of products that are assembled in a myriad of different ways. These include trays, mats, grids, flat plastic pipes, impervious liners, and geotextile filter fabrics.

Synthetic Drainage is the cutting edge of sports field design. The super efficiency of water transference through the surface (up to 13 times faster than gravel) makes synthetic drainage superior to the common gravel method.

The main advantages and disadvantages of synthetic drainage are:

Advantages1. Drains up to 13 times faster than the common gravel method. This makes

the cancellation of events due to rain a near impossibility and therefore revenue is not lost due to rained-out events.

2. Healthy natural turf is enhanced due to the following benefits; allows air and gases to circulate more easily through the soil profile, has a higher nutrient retention rate, promotes a greater root mass and reduces irrigation requirements.

3. Eliminates rubber migration in synthetic turf fields due to heavy rain.4. Has the ability to heat or cool fields more efficiently than current methods.5. The duplicity of price and application gives designers and sports field

contractors a distinct advantage regardless of the regional variables.6. Installs in a few days instead of a few weeks. This allows sports field

contractors to dramatically increase the number of installations they can achieve per season.

7. The rolled out drainage grid system is typically less expensive than the common gravel method.

Disadvantages1. The synthetic tray system is often too costly for most applications.2. Many systems do not have a satisfactory method to counteract the forces

of expansion and contraction.3. Sports field contractors may be hesitant to install a system they are

unfamiliar with.

Surface Gravel Synthetic

While the factors that help determine which kind of drainage system best suits the client haven’t changed; the recent evolution of drainage technology now provides many new options to sport field designers and installers. These new technologies are often superior and less expensive than the gravel method commonly used today.

The synthetic turf industry took several years before it saw the dynamic growth that it enjoys today. Synthetic drainage is posed to have that same kind of success if not greater.

For more information, contact Airfield Systems at (405)359-3775 or visit airfieldsystems.com

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