Porous Pavers for Temporary Parking

Jan. 4, 2017
7 min read

Editor’s note: This article first appeared in the July/August 2015 edition of Erosion Control.

Christ Chapel in Fort Worth, TX, is a growing church with expanding space needs: in particular, the need for more parking spaces to accommodate more congregants. During the summer of 2014, Concrete Paver Systems wrapped up a seven-month project that included providing erosion control for a temporary parking lot.

Concrete Paver Systems in Duncanville, TX, installs paver systems using concrete, clay, sand-set, mortar-set, and flagstone pavers as well as segmental retaining walls.

Editor's note: This article first appeared in the July/August 2015 edition of Erosion Control. Christ Chapel in Fort Worth, TX, is a growing church with expanding space needs: in particular, the need for more parking spaces to accommodate more congregants. During the summer of 2014, Concrete Paver Systems wrapped up a seven-month project that included providing erosion control for a temporary parking lot. Concrete Paver Systems in Duncanville, TX, installs paver systems using concrete, clay, sand-set, mortar-set, and flagstone pavers as well as segmental retaining walls. [text_ad] The company has used Grasspave² from Invisible ­Structures (ISI) in previous installations; the engineering specifications called for Grasspave² in this project. Grasspave² porous pavement is designed to function similarly to asphalt or concrete pavement with the aesthetics of a lawn. It provides a pervious load-bearing surface, filters and treats stormwater, reduces airborne dust, and reflects heat. “The church had three parking lots and wanted to put in Grasspave² so they could actually have grass in the parking lot,” notes Roger Henjum, partner with Concrete Paver Systems. The engineer’s plans had called for a 20-mil liner on the bottom. “Then we put in a drain core system, which is actually Grasspave² turned upside down,” says Henjum. “We put a six-ounce filter fabric on top of that. We put in 12 inches of a sandy gravel mix for a base, then we came in with the Grasspave² on top and filled the cores with sand. After that, a landscaper came in and put grass on top.” Runoff that doesn’t flow across the surface into the curb and gutter goes down through the rock to the drain core system at the bottom, hits the liner, and flows to the lowest end of the lot, where Concrete Paver Systems has set up a sump pump. Some 70,000 square feet of Grasspave² was used on the surface area and another 70,000 square feet of the product was used in the lower layer. The project provides temporary parking for the church. “They don’t open it up full-time,” says Henjum. “They don’t want people driving in there for the heck of it, so they put bollards up at the entries, and on the weekends when they need the additional parking they take the bollards out and let the people in there.” ISI specializes in site-development products that help with stormwater management such as porous pavements, underground stormwater storage, erosion control, and drainage and conveyance, says Dustin Glist, ISI’s media and information director. Six of the company’s seven products are manufactured from 100% recycled content. “Since Grasspave² has real grass as the surface course, we treat maintenance like any turfgrass system with the exception of aeration,” Glist notes. Grasspave² does not need to be aerated because of its sand-based root zone and because the roots are protected from compaction by the structure. Maintenance includes irrigation—if needed for climate and grass type—mowing, and fertilization with NPK fertilizers. Permeability holds up in cold climates, says Glist. “Tests have shown that porous pavements melt ice and snow faster, freeze water slower, and allow for better traction,” he adds. “Grasspave² comes in rolls that flex with freeze-thaw cycles and normal undulations in the terrain.” [text_ad use_post='27664'] Salt, magnesium chloride, and other snow and ice melting agents cannot be used on the system, Glist says. “Grasspave² has real grass, and chemicals will kill the grass. Snow removal should be done with skids or rollers attached to the bottom of the blade to ensure the blade does not make contact with the structure itself. Or a snow removal operator can raise the blade three-quarters of an inch above the surface.” Grasspave² is often used when LEED points are desired as it is manufactured with recycled content and offers urban heat island mitigation. For site development, it is designed to protect and restore habitat and maximize open space.

The company has used Grasspave² from Invisible ­Structures (ISI) in previous installations; the engineering specifications called for Grasspave² in this project. Grasspave² porous pavement is designed to function similarly to asphalt or concrete pavement with the aesthetics of a lawn.

It provides a pervious load-bearing surface, filters and treats stormwater, reduces airborne dust, and reflects heat.

“The church had three parking lots and wanted to put in Grasspave² so they could actually have grass in the parking lot,” notes Roger Henjum, partner with Concrete Paver Systems.

The engineer’s plans had called for a 20-mil liner on the bottom.

“Then we put in a drain core system, which is actually Grasspave² turned upside down,” says Henjum. “We put a six-ounce filter fabric on top of that. We put in 12 inches of a sandy gravel mix for a base, then we came in with the Grasspave² on top and filled the cores with sand. After that, a landscaper came in and put grass on top.”

Runoff that doesn’t flow across the surface into the curb and gutter goes down through the rock to the drain core system at the bottom, hits the liner, and flows to the lowest end of the lot, where Concrete Paver Systems has set up a sump pump.

Some 70,000 square feet of Grasspave² was used on the surface area and another 70,000 square feet of the product was used in the lower layer.

The project provides temporary parking for the church.

“They don’t open it up full-time,” says Henjum. “They don’t want people driving in there for the heck of it, so they put bollards up at the entries, and on the weekends when they need the additional parking they take the bollards out and let the people in there.”

ISI specializes in site-development products that help with stormwater management such as porous pavements, underground stormwater storage, erosion control, and drainage and conveyance, says Dustin Glist, ISI’s media and information director. Six of the company’s seven products are manufactured from 100% recycled content.

“Since Grasspave² has real grass as the surface course, we treat maintenance like any turfgrass system with the exception of aeration,” Glist notes. Grasspave² does not need to be aerated because of its sand-based root zone and because the roots are protected from compaction by the structure.

Maintenance includes irrigation—if needed for climate and grass type—mowing, and fertilization with NPK fertilizers.

Permeability holds up in cold climates, says Glist.

“Tests have shown that porous pavements melt ice and snow faster, freeze water slower, and allow for better traction,” he adds. “Grasspave² comes in rolls that flex with freeze-thaw cycles and normal undulations in the terrain.”

Salt, magnesium chloride, and other snow and ice melting agents cannot be used on the system, Glist says. “Grasspave² has real grass, and chemicals will kill the grass. Snow removal should be done with skids or rollers attached to the bottom of the blade to ensure the blade does not make contact with the structure itself. Or a snow removal operator can raise the blade three-quarters of an inch above the surface.”

Grasspave² is often used when LEED points are desired as it is manufactured with recycled content and offers urban heat island mitigation. For site development, it is designed to protect and restore habitat and maximize open space.

About the Author

Carol Brzozowski

Carol Brzozowski specializes in topics related to resource management and technology.
Sign up for Stormwater Solutions Newsletters
Get the latest news and updates.