Keeping Stormwater Out of the System

Chattanooga’s use of permeable pavers solves a flooding problem and sets an example

Keeping Stormwater Out of the System

After street work resulted in flooding issues near an intersection in Chattanooga, Tennessee, local business owners teamed with the city to install permeable pavers that alleviated the problem. 

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The problem of excessive storm runoff has a lengthy history for the city of Chattanooga, Tennessee. The antiquated water drainage system, which combines the city’s sewer system with its storm drains, poses ongoing challenges for city planners and engineers.

Common in many older municipalities, the simple system does its job until a torrential downpour, which overstrains the capacity of the treatment plant and causes overflow of raw sewage into the Tennessee River, a haven for outdoor enthusiasts and a source of drinking water for communities across the Southeast.

Due to updated 2014 mandates by the Environmental Protection Agency to reduce overflow, Chattanooga instituted multiple stormwater management programs, including a requirement for all new builders to capture rainwater before it enters the sewer. One of the ways they’re doing that is through the use of permeable interlocking concrete pavement.

The role of PICP in water abatement reflects an industry paradigm shift. It’s a solution to water management that works with the existing system. Realistically, cities across the country will have to replace outdated sewer systems in the decades to come, but the time and cost involved is astronomical and will most likely have to be done in increments. PICP systems offer viable long-term options that not only solve water runoff problems, but alleviate the strain on besieged sewer systems.

Improvement plans

In 2011, Max Poppel and Dan Rose opened The Crash Pad, a boutique hostel for adventure travelers located on Johnson Street’s south side. In 2013, as the travel refuge became increasingly popular, the pair decided to expand their enterprise by building a restaurant/bar on the adjacent property. But before finalizing plans for the restaurant, dubbed the Flying Squirrel, the partners had to overcome a major obstacle. Chattanooga’s old-style sewer system, along with recent repaving efforts, had resulted in a temporary flooding problem that created ankle-deep pools at the intersection of Johnson and Passenger streets.

The partners asked city officials for some possible solutions, one of which was a straightforward partnership proposal: Poppel and Rose would pay for PICP to completely resurface Johnson Street. In turn, the city would handle the entire installation. The proactive plan would eliminate the flooding, address the intersection’s structural issues and meet the city’s stringent stormwater management requirements for new construction.

“The cost of the pavers roughly corresponded to the amount of street improvements we were going to have to do anyway,” Poppel says.

After a careful vetting process, Belgard permeable pavers manufactured by Adams Products in Rockwood were chosen for this pilot project. The pavers are specifically designed to manage water runoff while creating an aesthetically pleasing road surface with a herringbone pattern and curb-free design.

“The stylish look gives it a European feel,” Poppel says. “We had always envisioned an active, approachable street with plenty of room for pedestrians and bikers.”

Stopping the flood

Mark Heinzer, engineering manager for drainage and flood control for the city, has been at the forefront of implementing environmental changes for water management.

He was involved in the Johnson Street retrofit project from its onset and recalls that the endeavor was a launching point for the city’s PICP initiative. Heinzer notes that the Johnson Street project delivered a dual service to the area by creating an appealing and versatile new road surface that solved an existing drainage problem.

“It captures that excess water at its peak, reducing the potential for overflow, and the road structure has maintained its integrity,” Heinzer explains. Nearly six years after installation of the pavers, the engineer reports, “There have been zero problems with rainwater. The water goes right through the surface of the pavement, gets underground and is held there. We’ve had absolutely no problems since the project with any kind of flooding.”

Darryl Sapp, Adams Products’ commercial consultant, explains the structural ingenuity that has allowed the Johnson Street makeover to remain in top condition and flood-free years after construction.

“The permeable pavers allow for rainwater to be captured before entering the sewer system,” Sapp says. “The water passes directly through a wearing surface into an underlying stone reservoir that temporarily stores the surface runoff before infiltrating into the subgrade soil.”

This is a stark contrast to the street’s previous traditional blacktop, which allowed no water absorption and created runoff problems during heavy rainfall.

“The use of PICP helped meet the redevelopment stormwater requirements and avoid the cost of installing stormwater management infrastructure directly on the proposed site,” Sapp says.

In addition, the paver system has proven much more cost-effective than traditional blacktop pavement. Potholes are now a thing of the past, and underground maintenance issues are vastly simplified. Heinzer cites the example of a recent waterline break that occurred beneath Johnson Street. “The Belgard PICP pavers were removed, the broken line was fixed and the pavers were repositioned.” If the road had still been blacktopped, jackhammers would have been required to tear up the pavement and the road surface would have had to be repaved after the fix. The permeable pavers saved time and money and avoided a noisy, messy repair on the bustling street.

Award-winning design

The Johnson Street retrofit project has been widely acknowledged for its innovative stormwater design solution to address urban flooding. The Crash Pad became the first hostel in the world to attain LEED Platinum certification for implementing green building design. In addition, Rose and Poppel were awarded the Tennessee Governor’s Environmental Stewardship Award in 2014 for excellence in green building for their contributions to the project — a high honor for a pair who went into business with the goal of “supporting our climbing and sushi habits.”

Due to the success of the Johnson Street retrofit and similar projects, the city of Chattanooga has endorsed PICP as a low-impact development solution to capture stormwater before it enters the sewer system. In addition, the city has developed an incentive program for property owners who replace asphalt parking lots with PICP.

Belgard’s permeable pavers have played an integral role in Chattanooga’s Johnson Street retrofit project. Six years after installation, the roadway serves as a thriving prototype for future designs.


ABOUT THE AUTHOR

 Kevin Earley is Director of Commercial Belgard Pavers for Oldcastle APG, a CRH Company.



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