Of the many debates held and decisions made when designing a sports field, the durability of synthetic turf versus the immaculate look, feel and maintenance of natural turf is one of the most divisive for parks and rec officials. Maintenance budgets are being cut, the cost of water is rising, and participation in sports is increasing. As a result, many municipalities and schools are going with the more durable, less-maintenance option. Offering potential LEED points (Leadership in Energy and Environmental Design) for water-efficient landscaping, reduction in potable water use, construction waste management and material reuse, recycled content and regional materials, the synthetic turf has become the common choice in green, sustainable design.
An Overlooked Component
Storm-water management, often overlooked within the construction of a synthetic-turf field, is one of the most critical design elements. Switching from a natural-turf field to a synthetic-turf field is the equivalent of switching from an open field to a parking lot. Natural vegetation is replaced with an impervious soil profile that relies on underground pipes to dispose of storm water. This widely accepted practice decreases natural filtration from soils, increases runoff quantities, and raises ambient air temperatures. The result has a detrimental effect on over-taxed storm-water systems, aquifers and even wildlife.
Making Runoff A Good Thing
With California preparing for its fourth consecutive year of drought, new solutions to water problems must be examined. Conservation alone is not enough. With proper design, runoff can be a valuable resource. Storm-water reuse and rain-water harvesting are concepts that have been used for years within parking lots and buildings, taking advantage of free water.
Rain-water harvesting and storm-water detention involve techniques to detain, filter, treat, and reuse on-site for potential irrigation, flushing toilets and maintenance, while reducing potable water consumption.
Too often, opportunities are missed to take advantage of potential storm-water mitigation simply by lack of knowledge. Sports fields are overlooked as potential mitigation areas for storm-water runoff, rain-water harvesting and elimination of potable water. Ninety percent of water that falls on synthetic turf is diverted into pipes and into municipal storm-water systems, whether it is rain or water used to cool or clean fields.
By combining proper design of the underlying drainage matrix of synthetic turf with holding tanks, filters, pumps and water treatment, parks can take advantage of the runoff from synthetic-turf fields. A typical soccer/football field has around 90,000 square feet (2.06 acres) of synthetic turf. One inch of rain per acre is equal to 27,154 gallons of water. With one inch of rain, it is expected that 50,343 gallons of water will be captured, and can now be used for irrigating surrounding landscapes that would have previously been supplied from municipal water systems.
27,154 gallons per acre x 2.06 acres = 55,937 gallons
55,937 x 90 percent runoff = 50,343 gallons of captured water
Wading Through The Process
In California, the Napa Valley Unified School District’s Memorial Stadium was slated for a retrofit to make it comply with modern standards. Part of the project included switching from living turf to a state-of-the-art synthetic-turf playing surface. However, the surrounding neighborhoods and storm-water system were prone to flooding prior to additional runoff from a synthetic-turf surface.
The district wished to pursue a rain-water harvesting system for the field. Upon completion of the master plan, very little landscaping existed within the stadium. After analysis of the landscaping budget and the amount of water needed, it was established that a 15,000-gallon tank would be sufficient to supply irrigation water to the landscaping. The distinctive attribute about this system from a traditional synthetic-turf installation is that the district can now run the water cannons to cool or clean the field for extended periods without wasting large quantities of water during a time of drought. It will be captured and reused within the landscaping.
Depending on the intended use of captured rain water, whether for irrigation or cleaning fields, there is typically a three-step process:
2. Primary filtration
There are many different types of holding chambers, internal tanks or cisterns that are capable of collecting large quantities of water. The type of installation will vary depending on the amount of water needed to be stored, budgets and locations. Typical installations include polyethylene tanks, concrete vaults, underground fiberglass tanks or even aboveground steel tanks. Underground tanks can be located under fields, parking lots and landscaping, while aboveground tanks can be used as focal points of buildings.
Filtering captured and stored rain water is an important preliminary step before treating or sterilizing water. Filters help eliminate any solids or contaminants that may have worked their way into drainage lines or storage tanks; this can potentially lessen or hinder the sterilization process. Typical filtration methods are:
3. Vortex filters.
Water quality and treatment are significant concerns for the safety and betterment of communities. Not knowing what virus or contaminates may be in rain water, treatment is of the utmost importance. There are many different types of water-treatment methods:
3. Reverse osmosis
4. Ultra-violet (UV) light.
Depending on the final desired application and budget, different standards for sterilization and treatment of water exist.
Another important and often overlooked component that can be installed is a smart EvapoTranspiration-based (ET) irrigation controller, which measures the amount of sun, rainfall and evaporation in an area. Since yearly water waste due to inefficient landscaping is significant, weather-based scheduling, as opposed to the typical “set it and forget it” irrigation, can save substantial amounts of water.
Regardless of the method to capture and reuse storm water, it is important to make the effort. The amount of water and money saved will be passed along to future generations of athletes.
Chris Chisam is a project manager and landscape architect for Beals Alliance in Folsom, Calif. For more information, visit www.bealalliance.com.