New Albany, Ohio, replaced an asphalt street with clay brick permeable pavers set on top of a 13-inch to 52-inch sub-base drainage layer of coarse aggregate.

At first glance, the question about what to do with Third Street in New Albany, Ohio, had a simple and straightforward answer: Re-mill it and lay down another layer of asphalt. When further inspection showed that the 12,200-square-foot street was in such bad shape that resurfacing would be a temporary fix at best, the conventional wisdom was to go in, dig everything up and start over. Once the old asphalt and storm drains were dug up, new drains would need to be set in place beneath fresh asphalt.

However, runoff would need to be re-directed somehow to address persistent stormwater problems near the bottom of the street, close to where it runs into the Rose Run stream. New Albany found that by going with a green, aesthetically pleasing solution that uses clay brick pavers in a permeable pavement installation, the costs were actually less than putting back a version of what was there before.

New Albany, about 15 miles northeast of Columbus, Ohio, is a classic American village — miles of white horse fencing and beautiful brick homes lead to a downtown city center. Brick buildings and pathways are steps away from the surrounding residential neighborhood. It's a place where it quickly becomes clear that both aesthetics and concern for the environment hold sway. The town directed Columbus-based engineering firm EMH&T to design a green street, especially as it related to where the water went after a rainstorm.

"Working with the stormwater master plan associated with this project, we generated some concepts to explore the best methods to deal with stormwater drainage," said Franco S. Manno, ASLA, LEED AP, and a senior landscape architect with EMH&T. "Our design options included bioretention, rain gardens, pervious pavement, and other green infrastructure options. Pervious pavement was the one that made the most sense for this project."

Stormwater filters through the 1/4-inch to 3/8-inch aggregate between the pavers where it is captured and held in the coarse-grade aggregate sub-base until the water infiltrates into the underlying soil.

The choice was to go with segmental paving, using a clay brick paver. "It was important to the design team that the end result would be a street that complemented the area and, clearly, the clay brick made the most sense," said Manno. "The village staff, planners, and the community wouldn't have accepted any other kind of material when it came to the aesthetic of the brick."

Several mockups were made onsite to show how they would look in daily use. StormPave in the Ironspot color, by Winston-Salem, N.C.-based Pine Hall Brick Company, rose to the top. Next to the street, a conventional English Edge paver, also by Pine Hall Brick, was specified for the sidewalks.

Green construction costs
The project wasn't a done deal because cost had yet to be factored in. The cost to install permeable pavers came in at $424,389. Estimates for putting in asphalt, including five years of maintenance, was $427,718; maintaining it for 10 years raised the cost to $434,085.

New Albany used a "best practice installation" for a permeable segmental pavement. The street was first excavated, more deeply toward the end nearest Rose Run Stream. A 13-inch to 52-inch sub-base of 1-1/2-inch to 3-inch clean fractured open-graded aggregate (ASTM D448 #2) was added, followed by a 4-inch choker course of 3/4-inch aggregate (ASTM D448 #57), and finally a 2-inch setting bed of 1/4 -inch to 3/8-inch aggregate (ASTM D448 #89). The clay pavers were laid on top of the setting bed and additional 1/4-inch to 3/8-inch aggregate was swept into the joints to provide interlock between the clay pavers.

Stormwater filters through the aggregate between the pavers where it is captured and held in the void area of the coarser-grade aggregates until the water seeps into the earth below, where it is filtered naturally as it recharges the water table. In heavier rains, water filters through the aggregate between the pavers and then downhill along the subgrade, where it is held in the deeper section of course-grade aggregate. It then passes through a sand filter before being released into the Rose Run stream.

As a result, no stormwater drains need to be installed with the permeable clay paver system, which provides a cost savings compared with a traditional asphalt or concrete street. The only maintenance needed is to regularly sweep or vacuum debris from between the pavers — and perhaps sweep more aggregates in between them, as needed. That's in marked contrast to regularly fixing potholes and resurfacing the entire street every five years. The cost savings was estimated at 75 cents to $1.25 per square foot.

 Paver advantages

In addition to the factors related to cost savings and aesthetics, use of permeable pavers means less land needs to be set aside as drainage ponds to address stormwater issues, which means more land is available for development. Therefore, businesses planning to build new developments near the village center will have fewer stormwater issues to engineer.

"It is no small feat to simultaneously improve our Rose Run stream and enable redevelopment," said Village Administrator Joe Stefanov. "We're accomplishing both."

The installation also means that the area will be safer. "These new pavers will drain better, producing less ice on the surface," said Public Service Director Mark Nemec. "Plus, because brick streets usually slow traffic, we expect a safer environment for motorists and pedestrians alike."

And streets made of modern clay brick pavers won't suffer the same fate as the asphalt they replaced. The American Society for Testing and Materials has several requirements for pavers (ASTM C902 and C1272) that are used in severe freezing and thawing conditions, such as those found in an Ohio winter. Requirements include:

• No more than 8 percent water absorption — Pine Hall Brick pavers have 4 to 6 percent water absorption, on average, which means that the product is fired to a temperature that produces a durable, long-term product without being over-fired to the point where chippage can be a major issue.
• A maximum cold to boiling water absorption of 0.78 — This measures the ability of the paver to withstand water expansion in freezing conditions to avoid spalling, the clay paver equivalent of a pothole. Pine Hall Brick pavers have an average of 0.58.
• Compressive strength of at least 8,000 psi and breaking loads in excess of 475 pounds per inch (lbs/inch) to withstand traffic loads — Pine Hall Brick pavers have a compressive strength greater than 12,000 psi and average 1,253 lbs/inch in breaking load.

Green benefits
Permeable clay brick pavers are green in several ways. They're made out of dirt and water, two of the most abundant building materials on the planet. Clay bricks cost less to manufacture than many other building materials — and they have countless recycling options. And the pavers themselves are the definition of sustainability, given that they will last for centuries.

Next to the street, a conventional brick paver was specified for the sidewalks.

In addition, Pine Hall Brick clay permeable pavers can enable architects to obtain LEED credits in four ways, including stormwater design, heat island effect (non-roof), recycled content (both of which depend on the color chosen), and use of regional materials.

Once installed, permeable pavers enable rainwater to take pollutants into the ground, where they are naturally filtered, instead of having them wash across the pavement and depositing them in a nearby stream. They also open up more land for development, because less land needs to be set aside as drainage ponds. Third Street is a pilot project and is the first of two brick streets planned in New Albany's historic Village Center.

"When we found out Third Street needed to be totally reconstructed, we wondered if we could do something more sustainable and environmentally friendly than traditional asphalt," said Stefanov. "It turned out we could, while staying under budget. Initial brick construction was only slightly more expensive than asphalt, and we expect maintenance and operational costs to be significantly reduced over the lifetime of the project. I am glad we were able to complete such an aesthetically pleasing project that is also very environmentally friendly."

Source: CEnews.com