The Practical Permeable Paver

Nov. 10, 2015

Cliff’s Cottage at Furman University
One of the goals set down by Furman ­University and Southern Living magazine when they began brainstorming the showcase home called Cliff’s Cottage was sustainability on an everyday basis. They wanted to demonstrate total sustainability while educating people on how to put the technology and practices to use in their everyday lives.

Scott Johnston, landscape architect and owner of Johnston Design Group in Greenville, SC, explains the original goals for Cliff’s Cottage, located on the university’s campus in Greenville. “There were three areas of importance to Southern Living magazine and Furman University. One was related to the occupant’s health and wellness. The second goal was economics though energy and water conservation. Designs included geothermal, low energy use and smart power, and rainwater that was collected in a cistern for use in the gardens. And finally,” he adds, “the materials had to be manufactured or obtained locally.”

In an almost unheard-of goal, they also specified the designs had to use materials that would make the entire home and outdoor space permeable. “Except of course, the roof,” clarifies Johnston. “That entire job site, from the time your feet leave your car, is 100% permeable.”

Johnston’s design firm is nationally recognized for designs in sustainable landscape architecture. He followed along and worked with the design and landscape architect on the project, Mark Byington. Byington is part of the Innocenti & Webel firm, based in the Carolinas office in Tryon, NC.

Johnston acknowledges that, with designs that include permeable surfaces and water storage onsite, a lot can go wrong. He stresses the importance of communication. “You have to really commit to working closely with your architect to make it successful.”

The 3,400-square-foot house had the potential for many challenges, but instead met each of the three goals. Seven years in the making allowed for the designers to carefully select the appropriate materials and incorporate them into sustainable technology and house and garden design. The designs for the walkways and gardens used permeable clay brick pavers, permeable concrete, and reinforced pea gravel.

“Each product was selected for infiltration and aesthetics,” says Johnston. “Both were important, as all permeable surfaces onsite drain into landscaped areas.”

Credit: Johnston Design Group
Cliff’s Cottage on the campus of Furman University

The walkways and terraces are made with Pine Hall Brick Company’s StormPave pavers. Approximately 1,000 square feet of the pavers were installed. It was also important that the pavers met the goal of being aesthetically compatible with the university’s Georgian style on campus. The Pine Hall open clay brick paver system helped achieve that goal. The system satisfies sustainability goals by allowing water to infiltrate, but also to be collected and used for garden irrigation. The system helps decrease stormwater runoff and controls, or eliminates erosion.

“Water is collected in perforated pipes, and then some is stored and some released to the garden areas,” explains Johnston. “In the ornamental gardens, they’re using native plant species in ornamental ways. They’re using the water from the permeable areas there.”

Additionally, he says, Furman has a large horticulture department that teaches sustainable, organic gardening. “They have a large organic vegetable garden there, and receive water from the building and from Furman Lake for irrigating the vegetables. And just in case there was some emergency overflow, it would move from the ornamental garden down to the Furman Lake. It’s designed that way.”

Credit: Eagle Bay
Parking area at the Coca-Cola bottling
plant in Charlottesville, VA

Cliff’s Cottage was later renamed the David E. Shi Center for Sustainability, and it has become a leading think tank where students, educators, and community members can gather to learn and teach about how to implement sustainable practices into daily living.

The project received Leadership in Energy and Environmental Design (LEED) Gold certification. “All of the permeable features had a lot to do with that Gold certification,” notes Johnston.

LEED was developed in 1998 by the US Green Building Council as a means of providing voluntary strategies to reduce energy and wasted resources from building construction and site designs. The Interlocking Concrete Pavement Institute lists permeable interlocking concrete pavements (PICPs) as being eligible for LEED credits. PICP limits runoff and water pollution by managing stormwater, thus helping to meet the LEED criteria for a sustainable site. Finally, because the third goal of the project limited the distance from which resources to be obtained, the project met LEED requirements under for construction in which at least 20% of building resources are manufactured within a radius of 500 miles of the project.

In terms of challenges on the Cliff’s Cottage project, Johnston says they found the reinforced pea gravel tends to move around some, but when it’s all finished, it settles itself out. So, the only real challenge turned out not to be much of a challenge.

Coca-Cola Bottling in Charlottesville
When developers talk of remodeling large stretches of industrial space in Virginia, chances are they’re looking at Richmond’s warehouse district. But when Riverbend Development construction manager Joe Simpson spoke of having a vision for an expansive Coca-Cola building, his project was located in Charlottesville, where industrial space is meager and historic sites well protected.

The Coca-Cola bottling factory, designed by Washington DC architect Doran Platt, was originally built on Preston Avenue in 1939. It was designed to be an Art Deco-style, two-story reinforced concrete ­factory that was faced with brick. In 1955, the factory got an additional one-story brick warehouse that served as bottle and crate storage; in 1981, a cinder block warehouse was added. The result for Riverbend Development when it purchased the property was 38,000 square feet of historical industrial space. Additionally, the famed architecture of the Art Deco era had earned the building a place on the National Register of Historic Places, which made the renovation work much more sensitive for planners.

Riverbend pushed right on through with the purchase at $2.7 million, with plans for offices, retail stores, and a rambling area for a beer hall, to encompass 6,000 square feet including a bar and seating for 250 occupants indoors and 150 more seats outdoors with ping-pong tables and bocce courts. A 28,000-square-foot parking area was included in the plans, using PICP.

Bob Bridges of Eagle Bay USA explains how the plan fit with Virginia’s requirements for runoff reduction measures. “A level 1 design treats one inch of rainfall, which satisfies the water-quality portion [of the stormwater requirements]. And with a Q10 rain event [a storm with a ­probability of occurring once in 10 years], when 51⁄2 inches of rain in a 24-hour period is treated before release—it satisfies the quantity treatment or volume treatment requirements. So in Virginia, PICP is a standalone BMP. It satisfies both quality and volume.”

He adds, “This project was just robust with LEED credits, of course.”

Eagle Bay’s SWM Pave system was selected, and Aqua-Bric 4 “L” pavers were installed. This system meets Virginia’s level 1 and level 2 design requirements. The L-shaped bricks interlock and meet requirements of the Americans with Disabilities Act as well. The bricks can be installed by machine or hand set.

The permeable pavement portion of the Coca-Cola parking lot took the Eagle Bay crew five days to install, Bridges says. “On average, we should be able to do 8,000 square feet of permeable pavement a day,” he says. “On this job we really didn’t have any challenges of any kind, so it went very smoothly.”

Credit: Credit: Country Landscapes
Iowa fairgrounds

Iowa’s State Fairgrounds
What began in 1854 as a small state fair in Fairfield, IA, has grown into the largest single event in the state. Currently located in Des Moines, the Iowa State Fair draws a million fairgoers annually from around the globe and is considered America’s most famous state fair.

The park-like fairgrounds include 450 acres and an adjoining camping area with an additional 160 acres for RVs and tents. In an effort to provide parking for fairgoers and vendors, along with a grass and lawn area for events at fair time, the ISF board decided to install Grasspave2, a porous flexible paving system, in one of the area’s trouble spots.

Credit: Country Landscapes
Placing the aggregate layer

“The space was designed to give the fairgrounds a multipurpose space for events and parking without compromising the grounds in the process,” explains Trever Ewalt. “The previous space was sparse grass due to the heavy fair traffic and would turn into a very messy area with any precipitation.”

Ewalt is a project manager and commercial project designer in the Commercial Landscape Division of Country Landscapes in Ames, IA. “The biggest problem was the overall aesthetics and functionality of the space,” he notes. “There was a very sparse stand of grass, and in a rain event, the space was practically unusable.”

Credit: Country Landscapes
Installing Grasspave in the parking and camping area

Since 1981, Country Landscapes has been designing and installing custom landscapes across the state of Iowa. With locations in central, eastern, and northern Iowa, it has provided landscape design for residential, public, and commercial sites.

Installing Grasspave2 from Invisible Structures, Ewalt says, provided an attractive solution and eliminated the stormwater problem. The system provides a stable surface for parking, driving, and walking while preserving a lawn-like, grassy landscape. It has load-bearing strength and protects the vegetation’s root systems from severe compaction. High void spaces throughout allow root development and storage capacity for rainfall. This was the kind of system the fairgrounds needed.

Credit: Country Landscapes
Laying sod

The 44,150 square feet of Grasspave2 is only a portion of the overall project. In addition, Ewalt says, roughly 7,000 square feet of Aqua Roc II permeable pavers from Belgard were installed in a roundabout area, all part of the fair’s movement toward more ecofriendly grounds. The Iowa State Fair is known for having the world’s largest livestock shows and the largest art show in the state. In the grandstand area alone, entertainment and outdoor concerts bring in nearly 600 exhibitors. All of this fun, unfortunately, generates a lot of waste and trash. The fairgrounds maintains an aggressive recycling operation and in 2014 alone recycled more than 54 tons of waste.

“The project is being installed in two phases,” says Ewalt. “The first phase was roughly two-thirds of the total and was installed in about two weeks—aggregate, irrigation, Grasspave2, and sod. The next phase will take a little less time to install. But the fair wants to add more Grasspave2 to the project if the budget allows.”

During installation, the project was blocked off by construction fence and treated as a construction site. The fair remained fully functional and weekly events continued as normal, which made vehicular traffic and site access difficult for workers at times.

Ewalt says some of the events were so popular and heavily attended that ISF officials asked that construction activities cease for a few days, at ­intervals. “We were able to work with the fair on these requests and still get the project done in a reasonable timeframe.”

The largest environmental challenge the system will face is the hot and dry Iowa summers. The system has an underground irrigation system to help the grass survive under these conditions.

“This particular system will be put to the test in mid-August when the Iowa State Fair is in full swing. Aside from heavy pedestrian traffic, the system will also experience traffic from a number of different vendors.”

He adds, “The fair has plans to use this open space to showcase its ag equipment and RV vendors. During other events—concerts, trade shows—the site can be used as parking for event goers. In between events, the fair will have an attractive green space. The Grasspave2 system will also keep the area drier during rain events.

“The turf areas will receive the routine maintenance as a normal lawn would, like mowing, fertilizing, and irrigation. This will be enough to keep this area looking great for years to come.”

Credit: WHPacific Inc.
Road improvements in Bend, OR, include
a bicycle and pedestrian corridor.

Oregon Bicycling and Pedestrian Program
Bend, OR, with a population of 76,693, is located in Deschutes County along the Deschutes River and on the eastern side of the Cascade Mountain range. Tourism is one of Bend’s largest economic engines, generating revenues of $570 million in 2011 and employing roughly 16% of the area’s workforce. With 23.8 inches of annual snowfall, the area is popular for downhill and cross-country skiing. Bend is also known for rock climbing, fishing, hiking, camping, and especially biking.

Assisted by an Oregon Department of Transportation (ODOT) grant, the city has completed roadway improvements to vital downtown corridors. The project that runs along NW ­Riverside Boulevard and NW Franklin Avenue is part of an ODOT Bicycle and Pedestrian Program designed to showcase state-of-the art, multimodal transportation safety. The project will increase the number of people walking and bicycling within the corridor while also providing additional stormwater management for the area.

Jeff Potts, P.E., with WHPacific Inc. of Bend explains some of the problems the project helped correct. “Bend is very bike-friendly, and this is a very popular park area. But previously it was uncurbed. So stormwater was sheet-flowing into the grassed lawn of the park, resulting in ponding on park walkways,” he says. “This project was funded by the ODOT grant to increase pedestrian and bicyclist safety within the Riverside Road Corridor along Drake Park.”

The Riverside Franklin Pedestrian and Bicycling Infrastructure will serve an important east-west connection across Bend’s downtown area and provide access to Drake Park, the Deschutes River Trail, and the Galveston Corridor. Drake Park is a 13-acre park, and the scenic Deschutes River, known also for white-water rafting, runs its north-south course through the city. Bend has more than 300 miles of mountain bike trails, with 51 of them being “in town” trails. The tracks and river routes are home to multiple running and biking clubs and competitions and have earned Bend the title of “Top Bicycling City” by Mountain Bike Action magazine.

One aspect of the project was to add curb extensions with permeable pavers, buffered bike facilities, shared arrow lane markings (“sharrows”), enhanced lighting, and landscaping that unites the parks and nearby neighborhoods. Some of the bicycle amenities, including buffered bike lanes, green bike lane markings, covered bike parking, and floating vehicle parking, was provided by Kittelson & Associates.

WHPacific proposed using Xeripave pavers from Ultrablock, which fit the project’s specific infiltration and durability requirements, Potts says. “The city of Bend, in conjunction with Bend Metro Park and Recreation, made the final selection based upon how they would complement existing and proposed features of the park.”

He explains, “Our design allows for local storage of runoff within rock galleries, up to a two-year storm event. In the event that rainfall exceeds the rock galleries’ storage capacity, runoff will flow along the curb line until it’s collected at the downstream catch basin.”

The city chose Xeripave Super Pervious (SP) pavers to use along the curbs. Each paver is 300 millimeters, or just under a foot, square and 90 millimeters thick. The pavers were placed in a 3-foot-wide curbside application. Sloping the asphalt toward the curbs allows stormwater to flow to the pervious pavers. Kevin Spencer Masonry installed approximately 1,000 square feet of the pavers. In total the project should infiltrate approximately 10,250 square feet of stormwater for the city.

“The city’s initial scope of services required investigating both permeable pavers with rock galleries, and conventional pavers with catch basins and dry wells,” says Potts. “As the design and review process unfolded, pervious pavers became the favored option because of their overall cost savings and ability to minimize damage to local root systems.”

Trees located nearby were an important consideration during the excavation of the rock galleries, Potts notes. “Ensuring that the rock gallery excavation did not damage the root system of nearby trees was a priority. We reviewed all root exposures onsite to determine the best course of action and reduced the rock gallery depth or width if necessary.”

Preparation for the pavers to be installed included a native soil sub-base, a geofabric impervious layer, a sub-base layer of 33⁄4 inches of open-graded rock, a base layer of 11⁄2 inches of open-graded aggregate, and a bedding layer of 1⁄2-inch open-graded aggregate.

“This layering configuration was selected to provide a suitable foundation for the pavers, while also allowing the necessary infiltration rate,” says Potts.

About the Author

Linda Robinson

Linda Robinson is a journalist specializing in agriculture and land-use planning.