Case Study: City of Atlanta Permeable Paver Retrofit

In 2015-16, the Atlanta, Georgia, Department of Watershed Management partnered with Belgard Hardscapes to install over four miles of permeable interlocking concrete pavement (PICP). The largest permeable paver retrofit project in North America, the installation includes several miles of roadways across neighborhoods near Turner Field, home of the Atlanta Braves. Phase I of the project started during the spring of 2015 and concluded in late 2016.

The Issue

As cities across the world grow, they give rise to more concrete, paved parking lots and miles of asphalt roads. During a large rain event in urban areas, these impervious surfaces cause runoff, which empties directly into drain systems that struggle to perform as infrastructure demand increases. In Atlanta, heavy rains repeatedly caused flooding problems in the neighborhoods of Summerhill, Peoplestown and Mechanicsville—areas adjacent to the huge parking lots at Turner Field and directly centered where Interstates 20, 75 and 85 convene. The shared singular draining system combined with these impervious areas contributed to regular flooding. In 2012, a particularly fierce storm sent runoff and raw sewage into people’s homes and backyards, causing the city to take action.

The Solution

Atlanta’s Department of Watershed Management started working on the Southeast Atlanta Green Infrastructure Initiative, which sought to develop a holistic approach to managing stormwater runoff and reduce flooding while promoting sustainability and enhancing community amenities. A key aspect of green infrastructure is that it provides an alternative to traditional pipe replacement by incorporating elements designed to mimic nature to more effectively manage urban stormwater and reduce flooding, erosion and sewer overflows. One of the immediate projects undertaken by the Department of Watershed Management was the decision to install approximately four miles of permeable pavers in the Peoplestown, Mechanicsville and Summerville communities.

Permeable Interlocking concrete pavement systems consist of concrete pavers with joint openings filled with permeable aggregate that allows stormwater to flow into layers of crushed stone that support the pavement while providing water storage and runoff control. As the rainwater sinks through the four feet of aggregate under the pavement, the rocks act as a filtration system to clean oils and chemicals from the street above. Geomembrane dams and the aggregate detain the water and slowly release it into the existing stormwater sewer system. Since the water does not run directly to the curb gutter, flooding is significantly deterred during heavy rain.

After funding for the $16 million project was secured, the team leaders chose Belgard’s Aqualine™ L-Stone permeable paver—in the appropriate color of Georgia Blend. Economically sound and surpassing all EPA stormwater requirements, Aqualine is designed to withstand vehicular travel in high-traffic areas. The pavement also delivers results in both cost-effectiveness and longterm durability in harsh climates, particularly those with extreme freeze/thaw cycles.

Installation of the permeable pavers was a three step process. First, the asphalt was removed. Second, the street was excavated and filled with stone along with a terraced dam system that detains the water and eventually carries it to the proper drainage area. Finally, the individual pavers are put into place on top of the stone and installed 12 square feet at a time using a machine. The unique “L-shape” of the stone allows for minimal waste during installation and provides optimal interlock for vehicular traffic.

The Belgard team worked closely with Amec Foster Wheeler to help plan the design build portion of the project. Using in-depth product knowledge and experience gained on past projects, Amec Foster Wheeler was able to better navigate challenges that occurred during installation such as unexpected utility cuts. In addition, Belgard worked with the City of Atlanta to develop a Permeable Interlocking Concrete Pavement Operations and Maintenance Guide. The document provides in-depth details on short- and long-term maintenance ranging from replacing pavers to winter inspection. The guide will ensure that the city saves time and money, and maximizes its investment for years to come.

The Results

Atlanta has adopted one of the most far-reaching post-development stormwater management ordinances in the nation, laying the groundwork for a robust green infrastructure program both for private development and the city’s capital improvement projects. Under the ordinance, new and redevelopment sites are required to treat the first inch of stormwater runoff with green infrastructure, such as bioretention (rain gardens) and permeable pavement. Over 2,000 construction projects that incorporate green infrastructure have been permitted in Atlanta since 2013, which equates to the removal of approximately 350 million gallons of polluted runoff from local streams and combined sewer systems each year.

As of June 2016, Belgard’s new PICP system is providing over two million gallons of storage capacity giving residents extra flood protection during heavy rain events. The city’s plan is to reach seven million upon project completion.

In June 2016, the Metropolitan North Georgia Water Planning District awarded Watershed Management with a STREAM Award for its Post-Development Stormwater Management Ordinance in a celebration held at the Loudermilk Conference Center. The STREAM Awards recognize the outstanding sustainability achievements of Metro water utilities and local governments.

Permeable interlocking concrete pavement systems continue to become an extremely popular choice for streetscapes and parking lots for municipalities and in the private sector. One of the biggest drivers for this technology is not just flood prevention, but also the Environmental Protection Agency’s Clean Water Act requiring builders to address their water quality impacts from stormwater runoff as well as neighborhood and street flooding. “A PICP system is the best of both worlds,” stated Aaron Faubli, Belgard Hardscapes Sales Manager. “You’re not just getting a pavement, you’re getting a pavement and a stormwater management system all in one.”