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Lightweight aggregates are providing new, consistent and cost effective options to address environmental concerns about the threat of stormwater to our clean water supply. Lightweight aggregates from Arcosa Lightweight provides design flexibility for stormwater management programs in meeting this environmental concern.

For stormwater applications, Arcosa Lightweight expanded shale and clay aggregate is environmentally inert, generally neutral pH, and absorbs water. Lightweight aggregate is a ceramic material made by calcining clay at temperatures in excess of 2000 degrees Fahrenheit.

As a filter medium, lightweight aggregate is very durable, and coupled with its porous structure and increased surface area, it is an exceptional filtering material for metalloids, suspended solids, oil and grease.

Arcosa Lightweight offers low-maintenance solutions that meet existing and proposed government regulations without the use of chemicals, specialized equipment or major facility upgrades. On-site stormwater management contributes toward LEED green building certification credit. The use of expanded shale and clay in such designs offers improved performance and longevity.

As a replacement for sand, lightweight aggregate raises the bar for stormwater treatment performance to new heights. The effectiveness of this new application is currently being tested by treatment unit manufacturers across the country. Lightweight aggregate has the long-term ability to absorb nutrients and maintain hydraulic flow to ensure that water treatment is effective and sustainable.




There’s a meadow five stories above the busy city streets of Nashville complete with green grass and rolling hills. This green space in the sky is actually the roof of a new convention center in the Music City.


The downtown development is part of the city’s green infrastructure program created to manage Nashville’s urban storm water challenges. The building boasts a 175,000 square foot green roof containing rooflite®, a certified green roof media manufactured by Skyland USA.

Ordinarily, rains pouring over the massive 1.2 million square foot building would drain into the city’s storm water system. But rather than tax the already strained system, some of which dates back to the 1880’s, most of the storm water landing on the new Music City Center will be retained by its specially designed roof.

“Storm water management is a huge problem and that’s why there’s a push for more green roofs,” says Skyland USA’s Managing Director Joe DiNorscia. “They allow 60 to 80% of rainwater to stay on a roof to be absorbed by the plants or evaporated. What’s left comes down slower and that gives the sewer system a chance to better handle the runoff,” he says.



One of the central features of a revitalized Atlanta landmark is the building's greenroof, which serves as a gathering spot and recreational area for tenants and visitors.


One of the central features of a revitalized Atlanta landmark is the building's greenroof, which serves as a gathering spot and recreational area for tenants and visitors.

The newly renovated historic property, now known as Ponce City Market, has a beautiful, natural space atop its downtown rooftop made possible by expanded shale and clay from Arcosa Lightweight.

A unique soil mixture, designed to ensure this roof always stays green, is a blend of Arcosa lightweight, sand, and organic compost. Scott King, of ERTH Products in Atlanta, says HydRocks works well in this type of application for two reasons: weight and absorption.

"Expanded shale and clay is the lightest material of its kind, and that really helps reduce the loads on the roof structure," says King. "It also has a very high absorption, which helps the plants in the green roof survive Georgia's hot summers and long periods between rain events."

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