Epic Battle

By: Aaron Reynolds, P.E.

Irrigation problems are not unique to California. When the Coast Unified School District (CUSD) sought to irrigate 130,000 sq ft of all-season, multi-use grass fields at an elementary school, it turned to an innovative subsurface irrigation system that reduces irrigation water usage by more than 50%.

Cambria Elementary School is located in Cambria, Calif., a seaside village nestled among the dramatic rocky cliffs and beaches between San Francisco and Los Angeles. Faced with limited water resources, erosion challenges and an elevation rise, which prevents adequate volume and pressure of irrigation water from reaching the 12-acre site, CUSD was unable to use conventional delivery systems.

To help design a plan to meet stringent water quality and erosion mitigation demands of the California Coastal Commission, CUSD contracted RRM Design Group for architecture and civil engineering services and Earth Systems Pacific for soil engineering. The team chose a water management solution that collects and stores more than 2 million gal of water from all available storm water and hardscape runoff.

The Environmental Passive Integrated Chamber (EPIC Chamber) system, available from Indianapolis-based Firestone Specialty Products, provides the school with a source of free irrigation water during the long, dry summer months by simply harvesting rainfall during the two-month wet season.

The system was fully customized for the site and includes two main components: The EPIC Chamber, which is an injection-molded, arched chamber that can be used individually or in series to provide a highly effective, clog-resistant drainage system; and the EPIC Pan, which is used as a water barrier for the chamber, allowing a certain amount of filtered runoff to infiltrate and recharge the groundwater table. The chamber system is non-pressurized with no moving parts, using the strategic placement of holes to control water flow through and out of the chamber. The transfer of water is a natural function of gravity.

The water management system designed for Cambria Elementary included six EPIC profile sections with a combined turf area of 130,000 sq ft. A storage capacity of 2.5 gal per sq ft provided 325,000 gal of initial storage. A secondary storage was created underneath an 87,000-sq-ft soccer field in an array of 5-ft-diameter linear sealed pipes that store another 1.7 million gal.

The soccer field is surrounded by a 6-in. berm to provide temporary storage in case of torrential rains. A 5-in.-deep profile over the field also provides an additional capacity of 269,000 gal. In all, the system can store approximately 2.2 million gal of irrigation water. With each pan/chamber cell covering approximately 25 sq ft, the project utilized 5,200 chambers.

For added durability across the school’s multipurpose field, the sand profile was reinforced with EPIC Netlon Advanced Turf System (ATS), which consists of small interlocking, three-dimensional polypropylene mesh elements. When integrated into the sand base profile, Netlon creates a reinforced layer that resists compaction and increases load-bearing capacities, while enhancing infiltration properties. This allows the grass to spring back to shape quickly, enhances student safety and helps resist the creation of ruts.

Heavy rain events and standing water can wreak havoc on parks and fields, especially during peak utilization periods. When the Firestone EPIC system is installed beneath a park or field, such as the Cambria school application, the system’s substantial drainage and filtration capabilities promote efficient land and water use and mitigate turf issues.

In addition to freeing up prime land space, the subsurface storage system is not subject to evaporation and does not promote algae growth. The system uses local sand and gravel in the profile to filter, collect and store runoff for reuse. This pre-filtration minimizes sediment accumulations in the reservoir over the long term.

While the EPIC pan/chamber cell application proved successful for the Cambria school, another effective alternative for capturing storm water runoff is to install an EPDM geomembrane beneath the EPIC system. When using the cured single-ply liner, water does not recharge the ground water table, and it can be stored and reused for subsurface irrigation.

“While the U.S. infrastructure struggles with a growing urban footprint, effective storm water management solutions are a focal point,” Firestone Specialty Products General Manager John Goers said. “However, the conventional curb and gutter system design treats storm water as a waste product to be moved from one location to another as quickly as possible. Comprehensive water management solutions, such as the EPIC chamber system, represent a significant paradigm shift and offer a true onsite water management and reuse system.”

On the Cambria campus, the EPIC system collects enough water to meet all landscaping needs year after year, delivering a sustainable and economically sound solution.

Aaron Reynolds, P.E., is water management solutions manager for Firestone Specialty Products, Indianapolis, Ind.

Firestone Specialty Products
250 West 96th St.
Indianapolis, IN 46260
800-428-4442
info@firestonesp.com
www.firestonesp.com/ispp