PRB Articles


Wringing Out The Water

The multiple-use sports field is the Swiss Army Knife in your sports-facility arsenal.

No matter what sport or event you're talking about--soccer, football, even festivals--that type of field has the flexibility to take it on.

No area has more use, no surface sees more foot traffic, and sadly, no facility gets less rest.

The fact that many fields see games scheduled back-to-back--and often end-to-end if the area is large enough--means the fields have to bounce back after a rainstorm and be ready for play.

Let's face it: A facility with games almost every day of the week doesn't have much wiggle room in terms of scheduling. It can't afford to stay muddy for days on end.

While many rec and park districts are starting to implement the use of one or more synthetic-turf facilities (which have the advantage of mechanical drainage systems, making them ready for play almost immediately after rain), the vast majority of the municipal multi-use fields are composed of natural grass.

Here's a little-known fact, though: Natural fields can still hold up to the weather. All they need are solid construction (including the right soil for the weather conditions and intended use), and regular maintenance.

From The Ground Up

All fields, no matter the type of grass, need the correct soil. There are two basic types of natural-grass fields:

1. Native-soil

2. Sand-based.

A native-soil field may be a true native field, in which only the soil found at the site is present, or a modified native-soil field, or a sand-cap field.

A sand-based system, on the other hand, is one in which the native soil is completely removed and replaced with an under-drain system and a drainage media layer (principally stone and rootzone material that is largely sand) to improve drainage.

Neither type of field is “better” per se; however, one may be better under certain conditions.

According to the book Sports Fields: A Construction and Maintenance Manual, “The main problem with native-soil fields is drainage. Most native soils absorb water quite slowly and cannot handle large amounts; therefore, without additional provision for drainage, these fields can easily become muddy, worn, and/or unusable.”

Unfortunately, over time, native soil can compact. Constant use (something all multi-purpose fields have), mowing, irrigation, and more will flatten the soil, making it tighter and harder. When water then falls on the field, it takes longer to migrate down through the soil and many times becomes trapped.

The result is a muddy field that is easily torn and scarred by athletes. The constant use creates a self-perpetuating cycle of damage, leading to a field where grass can’t grow.

Experts recommend that fields be closed and allowed to rest while soil is amended, and/or new seed or sod is put in. Unfortunately, cities and field managers are often at cross purposes because many municipalities--in order to generate the funds necessary to keep facilities upgraded--will allow park fields to be booked by out-of-town teams for regional and state tournaments.

This may result in back-to-back scheduling that covers not only weekdays but weekends, evenings or other times, and in turn makes it difficult--if not impossible--to set aside fields.

Drainage Principles

Want good drainage? Start by ensuring that any water on the field comes from either rainwater or planned irrigation. In other words, water shouldn’t be traveling onto the field after dripping off the roof of a storage shed or dugout, running down a nearby hill, etc.

Proper drainage around and under such areas will help lessen the potential of excess flooding from other sources.

Slope And Crown Requirements

Each field has a specific slope and crown requirement. These two elements of design and construction are essential to moving water off the surface and toward the sides of the field, where drainage mechanisms can take care of the water.

One area out of tolerance can make the field muddy, or at least soft, and prevent it from playing well. In general, water should be moved off the field by directing it the shortest possible distance.

Different governing bodies, such as the NCAA or the NFHS, will require varying degrees of slope for each sport. Since rules can and do change from year to year, be sure you are working with the most current version of the rules for the correct governing body prior to embarking on any grading work.

Drainage Techniques

Drainage is a field's best friend; however, because it's invisible to the untrained eye, it’s the one item many owners forego in place of a flashier improvement (better stands, electronic scoreboard, etc.). The long-term success of the field, as well as its day-to-day usefulness, is tied to its ability to drain water.

A subsurface drainage system (so called because it manages the water that makes its way underground) can help fields dry more quickly. Many factors must be considered in determining the correct drainage system, including (but not limited to) soil type, local precipitation, field use, budget, existing slope, and local regulations. Work with a design professional to choose the right type, with the correct specifications for the amount of water you want to move.

The traditional type of drainage system for a sports field has been the pipe drain, which uses perforated pipe placed in trenches in the subgrade, which is then surrounded by coarse sand or clean stone to within 4 inches of the surface of the subgrade and capped with sand. Water then drains through the rootzone and stops in the trench, where it enters the pipe from the bottom. Drains are typically placed 3 to 10 feet apart for native soil, and 10 to 30 feet apart for sand-based fields. They are surrounded by clean stone or coarse sand.

Another type of system includes flat drains, sometimes called strip drains, 6 to 18 inches wide and 1 to 2 inches thick, without a wrapping of filter fabric, and placed horizontally on the subgrade during construction. They also may be trenched in and placed vertically after installation of the rootzone, in either native or sand-cap fields.

Builders note that the sand-vein system, sometimes called a sand-silt system, is the least expensive (and still highly effective). This system works particularly well in a native-soil field, often lasting for years without problems.

Keeping It Up

Mowing, irrigating, fertilizing, and weeding. Everyone knows these basics, but few seem to add preventive maintenance into the mix. And these days, with shrinking budgets, maintenance is often the first item to go. This can be a real problem, particularly in rec and parks installations, which generally cannot pay the amount needed for the maintenance that would normally be required of heavily used fields.

Ultimately, regular upkeep is the one action that can keep a field on track, and help avoid large expenditures down the line. Ideally, maintenance should include fertilization, weed control, aeration, and topdressing, and, of course, the elusive rest periods needed to help the field recover from heavy use.

Do a regular walk-through of the field. Check for signs of weeds or pests, and take action quickly while any problem is still relatively minor. Check all aspects of the drainage system to make sure it isn't degrading over time. Head to the fields during or after a rain and check whether water is moving off the fields or standing on them. A field builder can help you check the sand- and silt-style drains and find whether they need an upgrade.

Drain lines and inlets should be inspected and cleaned as well. If a track encircles the field, check the adjacent drains routinely to be sure they have not become covered or clogged--something else that contributes to water ponding on both the field and the track.

There isn't any one secret to keeping a field in good repair; rather, regular upkeep and proactive care will ensure a better playing surface over time. Like the athletes who play on it, staying in shape is the key to long-term health for the field.

Note: The American Sports Builders Association (ASBA) is a non-profit association helping designers, builders, owners, operators, and users understand quality sports-facility construction. The ASBA sponsors informative meetings and publishes newsletters, books, and technical construction guidelines for athletic facilities, including indoor sports surfaces. Available at no charge is a listing of all publications offered by the Association, as well as the ASBA’s Membership Directory. Info: 866-501-ASBA (2722) or www.sportsbuilders.org .

Mary Helen Sprecher has been a technical writer for more than 20 years with the American Sports Builders Association. She has written on various topics relating to sports-facility design, construction and supply, as well as sports medicine, education, and health and industrial issues. She is an avid racquetball and squash player, and a full-time newspaper reporter in Baltimore, Md.

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