Permeable Paver Projects Increase Useable Area

Dec. 20, 2016

As the use of green infrastructure becomes more widespread, and more properties need to manage as much stormwater runoff as possible onsite, the use of permeable pavers is increasing—on both new and retrofit projects.

Case in point: some 43,000 square feet of UniGroup’s UNI Eco-Stone pavers was installed in 2003 at Schmelz Volkswagen in Maplewood, MN. John Schmelz, the dealership’s owner, notes that in his community, one-third of property must be laid aside as a detention pond for a 100-year-storm.

“We park cars. We need to have the parking space,” he points out. “The challenge was you have to have a hard surface, either cement or asphalt. If we asphalted that, we figured that would cost. We would never cement it.”

But the city’s requirements would have taken nearly half of the parking spaces Schmelz needed for his dealership inventory.

The project’s contractor, the Rehbein Companies, suggested using permeable pavers, which freed up space for 900 parking stalls. The Uni-Group permeable interlocking concrete pavers were manufactured by Borgert Products and installed by LPS Pavement Company.

The pavers are 3 and 1/8-inch thick, and measure 9 by 4.5 inches, and were installed atop a 2-inch-thick bedding of ASTM No. 8 aggregate on a 20-inch base of No. 57 stone.

The county offered a stormwater credit for the project, which serves as a demonstration tour for the Minnesota Erosion Control Group.

The dealership’s owners have been impressed with how long the permeable interlocking concrete pavers have lasted without presenting typical pavement issues—for example, there is no puddling as a result of torrential rains.

A Street Upgrade
In New Albany, OH, city officials sought to replace a worn-out asphalt street with more durable material. They chose StormPave permeable pavers from Pine Hall Brick Company.

Doug Turney, project manager and green infrastructure practice leader for EMH&T, a Columbus, OH-based firm of engineers, surveyors, planners, and scientists, says the project replaced an old street with a curb. There were some flooding and water-quality concerns involved as well. The street had no storm sewer and, thus, did not drain well.

“We looked at the cost comparison of doing pervious pavement versus doing traditional rehab,” says ­Turney. Choosing the pervious paver system turned out to be cost-neutral.

Turney says the city architect’s original choice was concrete, which he believed would be less expensive. However, StormPave permeable pavers offered a more traditional—and more attractive—appearance, notes Turney. Some 15,000 square feet of the product was installed in 2011.

The permeable clay pavers are designed to allow rainwater to filter down through a specially constructed system, with pollutants dissipating into the soil rather than being carried into the storm drain system.

“The city and some watershed groups were trying to get better water quality on Rose Run, the stream that it drains to,” explains Turney. “This is something that was done to help that.”

The project offered some lessons going forward with the use of any type of pavers, he points out.

“The soil compaction was visual, and, at the time, we rolled it pretty good,” he says. “There has been some rutting of the pavers—a half inch, a quarter inch. You really can’t tell unless you walk on it.” He says he is uncertain of the cause of the rutting but it could be because the base material has shifted.

Since that project, Turney’s firm has been involved in larger installations with concrete pavers, and has worked with David Smith, technical director of the Interlocking Concrete Paving Institute, on issues of compaction. Whereas on the New Albany project, compaction was done on a visual basis, Turney is now working with Smith on the use of a lightweight deflectometer, which presents “a quantitative way to measure how many times you have to roll it to get it tight,” he says. “It’s something more quantifiable than just visual.”

Marc Barnes, spokesperson for the Pine Hall Brick ­Company, points out that snow removal on clay pavers such as StormPave should be done with a rubber-tipped shovel or plow to reduce the chance of chipping, something that many other companies and installers also recommend for their products.

Credit: AQUA-PAVING CONSTRUCTION
North County Transit Center

North County Transit Center
With the success of already-established projects evident, ­current stormwater mitigation projects are increasingly incorporating permeable surfaces.

In Ferguson, MO, officials sought to incorporate green infrastructure into a bus terminal—part of the North County Transit Center—that would serve as a pilot project for the Metropolitan St. Louis Sewer District (MSD). Stormwater mitigation is one of the district’s responsibilities.

Permeable pavement was chosen for installation in an area for vehicle parking that is surrounded by a raised concrete platform where buses pull in, pick up passengers, and move on.

Credit: OPN ARCHITECTS
Cedar Rapids’ Greene Square

The work was done in spring 2016, when Aqua-Paving Construction mechanically installed 21,000 feet of Advanced Pavement Technology’s Romanstone Aqua-Bric Type 4 and Aqua-Bric Type 1. Both were manufactured for that job by Midwest Block and Brick.

Derek Schneider, vice president of Aqua-Paving Construction, notes that MSD wanted the transit site to be permeable, with all water processed onsite. Water is channeled through the pedestrian area onto concrete pavement and then onto the permeable area.

The Aqua-Brics are used as part of the Bio-Aquifer Storm System (BASS). Runoff from the site drains into an aggregate-filled space beneath the pavers, and bacteria contained in the aggregate help to break down pollutants. The system is designed to support heavy vehicles and can be used in parking lots, driveways, and similar areas.

The project is serving as a test site to determine how St. Louis metropolitan authorities will proceed to “green” the area, notes Schneider, adding that green infrastructure could help reduce erosion and water-quality problems, especially in areas adjacent to the Mississippi River.

“They did a lot to make sure this had a smaller footprint carbon-wise than you would normally see,” says Schneider. “This is the first facility they had done for the metro area. There are some permeable pavement projects there, but all of them are private. They wanted to create a new design so the Metropolitan St. Louis Sewer District can use that for other municipal projects throughout the St. Louis area.”

Schneider says the transit site encompasses a number of observation wells so MSD officials can constantly monitor how much water is being taken in and held, and how fast it is going out.

In terms of the permeable pavers’ maintenance and performance in winter months, Mike Corteen of Advanced Pavement Technology says that freezing temperatures do not reduce the permeability of the pavement system. “The open-graded aggregate structure of the system allows the melted water from ice and snow to pass through it,” he says. “It is not held below the pavers to allow it to freeze. Road salt does not affect the permeability either.”

Many users report they are using less deicer, as the ice that is initially melted by the salt drains from the surface instead of refreezing in pools as it would do on asphalt or solid concrete, Corteen says.

“You can plow permeable pavers, and as long as they are properly installed, there is minimal risk of any damage,” he says. “A steel plow blade may scratch the surface and leave rust marks as it does on asphalt or concrete. But on a commercial application the pavers are not always pigmented, so it is usually not an issue to the owner.”

Some snow removal companies use acrylic plow blades or a rubber boot on steel plow blades that reduces the rust and scratching that may occur from a steel blade, Corteen points out.

“The rust is an aesthetic issue, not a functional one,” he adds.

Greene Square
In Cedar Rapids, IA, the city and several public and private entities banded together to redevelop and revitalize the city’s only downtown green space—Greene Square—bringing urban sophistication to the space while honoring the park’s history.

After working with these groups on a vision for the park, OPN Architects of Cedar Rapids was hired to design the project, working with a steering committee of city representatives and stakeholders representing the organizations adjacent to the new square, such as the art museum, the library, a church, and a daycare center.

Credit: JOE BAZEY
Pavers increased building space and help keep the site cooler.

The final design removed one of the park’s pathways, redirecting traffic through the core and activating the ­relationship between the library to the south and the museum to the north. OPN also incorporated ample seating, with traditional park benches, café tables on a new patio, new planters around the edges of the space, and five curved seat walls.

“We devised an elegant design that was urban and modern, and yet fun and whimsical,” notes Stacey Hanley, associate AIA, ASLA, LEED-AP, of OPN Architects. “One of our primary objectives was to incorporate elements for families and children, bringing a wide variety of people to engage with the square and park space.”

Central to that goal, is the new fountain designed to be both aesthetically pleasing and accessible for play, lit at night, and covered with durable orbs that create visual interest in the winter. The fountain has been a hit since the park reopened in spring 2016. With children playing in the fountain from sunrise to sunset, running on and off the pavement area, though, a muddy area started to form.

Hanley notes that it is a “good problem to have,” because it shows that the structure is being well received. What wasn’t so desirable was the wear and tear in some areas. In an attempt to mitigate that, the city added an additional hardscaped area around the fountain. “We weighed in with some ideas of how we could incorporate a drain and went through several iterations,” notes Hanley.

The idea of going with a stainless steel drain presented concerns over slip issues and costs.

“We looked at doing an open trench with gravel, but then we were concerned that children would trip,” says Hanley.

In the end, the team chose to use ­permeable pavers.

“The pavers worked well with the park’s design, and we thought that was a good way to capture some of the runoff from the fountain and provide a nice non-slip material for the children to run on,” she adds.

Ultrablock Xeripave Super Pervious Pavers were installed around the perimeter of the water feature in mid-June 2016.

Xeripave requires periodic maintenance, with the frequency determined by the contaminant profile of the area in which the pavers are installed. Xeripave is maintained by using a pressure washer, shop vacuum, or city sweeper.

“A vehicular application would need to be maintained more frequently than a pedestrian area,” notes Debra McNamara of Ultrablock.

Xeripave is freeze and thaw resistant, due to a void capacity that exceeds 35%, creating an open-celled system, she says.

“These voids allow room for water to expand and condense during freeze and thaw cycles without affecting the integrity of the paver,” says McNamara, adding that Xeripave is not affected by road salt.

The pavers can be plowed over, but would require a rubber-tipped blade on the snowplow.

Mark Walker, business development director at Kuert Concrete, notes that the Chicago Department of Transportation (CDOT) began using Xeripave more than three years ago to satisfy stormwater management needs within the Chicago Green Alley project.

“Chicago snowplows have no issues with the pavers as long as rubber blades are used,” he notes. “The only issue caused by using steel blades is an occasional paver getting caught on the corner, thus flipping it out of place, but the same could be true with a typical brick-paved surface. Twice a year, the Chicago street maintenance department maintains these alleys with their street vacuums. This BMP was adopted for maximum infiltration.”

“Man Caves”
Joe Bazey runs a business in Columbus, MN, called Garage Solution Condominiums. The garages, or “man caves,” as he likes to call them, are intended for those who do not have such space on their own property.

Unlike a typical storage unit rental business, Bazey offers storage condominiums for those who have recreational vehicles, campers, boats, snowmobiles, trailers, and, as he puts it, other “toys” for storage and care.

For example, some people use the space to build a model plane, do hobby woodworking, or refurbish a vintage vehicle. It’s also become somewhat of a hangout for the unit owners, Bazey notes.

The complex has three separate buildings. Each unit is heated, plumbed for water, and wired for electricity. The site also has fencing and security.

With a business like this, it is important for Bazey to protect the facility as an economic investment. He had LCI Landscapes install 46,000 square feet of Borgert permeable pavers. The installation was done in three phases, with the last section finished in October 2015.

“We went with the pervious ­pavers mainly because of the beautiful look, but also you gain all that square ­footage,” he points out. “My land was 50% pervious and 50% non-pervious surface. By doing the ­pervious pavers, I was able to add on another 20,000 square feet of building to be able to sell, which offset the cost of the pavers.”

Additionally, the pervious pavers prevent potential flooding that might compromise the contents of the units.

Bazey says his business sits on sandy soil and that there is only 15 inches of rock underneath the pavement.

“It drains very well,” he says. “I absolutely love it. I love the looks of it. I got lucky because I had stone on my building and they had a color that matched the stone, so it went very nicely together.”

Bazey says he favors the environmental benefits of the pavers enabling water to go back into the soil.

“For me, it made total sense, because I can offset the cost with adding more units,” he says. “But you can also offset the cost by doing less pond work and less piping. You don’t have to do a lot of drain pipes.”

He also appreciates that the pavers don’t generate the same amount of heat as asphalt. “In the parking lot, we’d be 10 degrees warmer,” he says. “In the winter, snow would start melting and then refreeze at night. Now, the water has a place to go when the snow melts. It doesn’t sit on top and refreeze. When it starts melting, the water goes into the pavers and they seem to clear off a lot quicker than concrete does.”

Bazey says he’s had no special maintenance issues during the winter weather. “You can put road salt down, although we don’t,” he says. “There’s road salt falling off from the cars when they drive in and nothing has been affected by that yet because of the sealer that’s on the pavement. You can seal it even more if you want to, but I choose not to.”

As for snowplowing, “as long as you install them correctly, you’re not going to have any issues,” notes Bazey. “We use a poly blade on the snowplows so as to not scratch the pavers up with a steel blade.”

Bazey also finds the pavers to be durable. “We’ve had ­tractor trailers, garbage trucks, and sewer trucks come through,” he says. “There are no issues at all.”

About the Author

Carol Brzozowski

Carol Brzozowski specializes in topics related to resource management and technology.