Bell Middle School stabilizes slope with PROPEX Pyramat 75

Problem

The Bell Middle School campus is located on a hill in the Paradise Hills community. The school’s intermural fields are located in an area that was formerly a sanitary landfill. The south landfill slope was initially stabilized with geocell, but due to the steepness of the slope, lack of vegetation and erosion from precipitation events, the geocell began to fail. As a result, eroded soil was deposited in the backyards of several homes located at the toe of the slope.

Solution

The school district determined that the geocell needed to be removed and replaced with a more durable and long-term solution. PROPEX® Pyramat® 75 high performance turf reinforcement mat (HPTRM) was selected because it delivers superior erosion protection of slopes for up to 75 years and is designed to promote root development and vegetation. PROPEX Pyramat 75 has been proven to greatly improve hydraulic resistance limits by reinforcing vegetative root structure and providing greater stability during and beyond vegetation establishment.

Performance criteria for channel stabilization materials have traditionally focused on hydraulic parameters like shear stress and flow velocity, but field performance is also highly dependent on non-hydraulic factors including UV resistance and tensile strength. This is especially true for arid and semi-arid environments where vegetation can be sparse. PYRAMAT 75 features a proprietary ultraviolet stabilizer package, high tensile strength, and superior hydraulic performance, to provide up to 75 years of slope protection and erosion mitigation in environments with limited vegetation and direct exposure to sunlight. Phase one of the slope renovation included removal of the geocell, regarding the slopes, installing 3,700 yd² of PROPEX Pyramat 75 and establishing vegetation. The woven structure of the HPTRM allowed for existing cacti and scrubs to be saved because the HPTRM can be cut to fit around existing plants.

Outcome

PROPEX Pyramat 75 was installed in 2018 and continues to successfully stabilize the slope. Since installation no erosion has occurred, mitigating sedimentation deposits into the yards of nearby homes. The HPTRM system also helps reduce pollutants and encourages infiltration of water back into the groundwater table. These are two reasons why the EPA has identified systems that utilize HPTRMs like PROPEX Pyramat 75 as a Best Management Practice (BMP) for improving water quality. Due to the successful results, the school district is planning additional Phase two and three of the slope renovation to replace existing geocell.