Performance

ClosureTurf™ has been extensively tested in the lab and in real-world applications for performance and durability. The goal was to produce a system that performs better than current Subtitle D rules require and can resist the many common failure modes of today’s closure covers. Over a period of several years, we evaluated many component combinations and tested them under very extreme conditions. After many trials, we developed the optimal combination of materials found in ClosureTurf™. Both research labs and independent professional engineers have tested the system.

The synthetic grass technology was originally developed for professional sport venues. Over the last decade the market has expanded while the technology has improved. The latest generation of polyethylene material now provides excellent residual strength and color durability against UV light.

By combining the newest synthetic turf technology, the stability provided by high friction coefficients, a “locked in” ballast system, and high flow transmissivity, ClosureTurf™ significantly outperforms current closure methods at a lower cost.

The driving performance criteria for ClosureTurf™ are stability, transmissivity and durability, while mitigating emissions and infiltration. The graphs and charts summarize some of the evaluation results collected for the product.

Stability

Of primary concern on landfills and mine piles is the soil cover’s sliding along steep side slopes, particularly after major storms. With ClosureTurf™, rainfall penetrates quickly through the sand infill and drains directly into the geocomposite drainage system below, avoiding sand erosion and maintaining sand infill stability. The infill, held in place by the synthetic grass’s unique structure, provides ballast that anchors the synthetic turf to the surface it covers. Note that:

• ClosureTurf™ can be placed on very steep slopes
• Friction tests indicate 43 degrees internal friction value
• The slope stability safety factor can be calculated from the chart and using the equation:

SF= tan φ/tan α

Drainage

ClosureTurf™ infill material is stable on steep slopes under severe weather conditions. Sand infill stability is controlled by the following product characteristics:

• Percolation/ Permeability
• Transmissivity
• Sand friction / grass interlocking
• Sand gradation

ClosureTurf™ was designed with the above characteristics in mind: the sand infill will handle more than 4 inches per hour of rainfall without any erosion. Rainfall penetrates quickly through the sand and into the AGRU drain liner below, which has large transmissivity. Erosion energy resides in the structure geomembrane and not in the sand surface.

Weathering

Life Expectancy

ClosureTurf™ demonstrated four times the required amount of residual strength at 30 years in an independent study of weathering and survivability. The strength required is based on applied loads of pullout forces from equipment operation and water runoff forces (approximately 3 to 4 pounds per blade). We conservatively evaluated only the exposed grass above the infill. The grass below the infill, which is mostly protected from UV, will have a much higher strength than that of the exposed grass.

Studies show excellent UV performance of the polyethylene yarns. Tested under extreme conditions in the Arizona desert for over seven years, the yarns still show a tensile strength reduction of less than 15%, and almost 60% (four times more than required) of retained strength after 30 years, making them extremely suitable for a long life of harsh exposures.

(FIFA) tests of solar radiation exposure on European fields indicate a reduction of less than 10% over 20 years.