Garden Variety

Saint Louis Retaining Wall Co., a supplier of masonry and precast landscape systems, is teaming up with energy provider AmerenUE, Southern Illinois University

Saint Louis Retaining Wall Co., a supplier of masonry and precast landscape systems, is teaming up with energy provider AmerenUE, Southern Illinois University Edwardsville, and Louisville, Ky., coal combustion products processor Charah, Inc., to investigate the use of bottom ash in landscapes. A by-product of burning coal to generate electricity, bottom ash as a component of precast retaining wall units will potentially contribute to the development of a significant ÎgreenÌ wall system.

Our vision for more than 16 years has been to transform conventional retaining wall manufacturing and construction methods into environmentally friendly and structurally sound retaining wall systems that enhance the natural environment and surroundings of each landscape project, affirms Mark Woolbright of St. Louis Retaining Wall, Bridgeton, Mo. Accordingly, years devoted to research, manufacturing innovation, and observation of 3 million-plus square feet of installed projects have enabled the producer to develop and patent a green retaining wall system utilizing a specialized, recycled bottom ash from electric power generation. The green wall system is similar in intent and function to green roofs currently used for many LEED [Leadership in Energy and Environmental Design]-certified projects around the country.


Evaluation of Saint Louis Retaining Wall’s new EcoWorks system is underway at Southern Illinois University Edwardsville (SIUE), a leader in research and testing for green roof technologies through the Green Roof Environmental Evaluation Network (G.R.E.E.N.). Once the study is complete, the producer asserts, its high-impact green materials will set a new standard nationwide for environmentally friendly retaining wall systems for both commercial and residential projects.

Dr. Bill Retzlaff, associate professor in the Department of Biological Sciences and the Environmental Sciences Program, and his graduate students have constructed and planted 18 test green walls in order to evaluate their plant growth, thermal benefit, and storm water performance over the next three years. Collection and analysis of data by Retzlaff, along with his colleague Dr. Susan Morgan of SIUE’s Civil Engineering Department, began shortly after Labor Day.

The SIUE research team will measure plant growth of five Sedum species in the wall systems with north, south, east, and west light exposures. Thermal performance of the same four aspects also will be monitored. The design of the 18 test walls permits all storm water flowing through each structure to be collected and quantified for comparison to a nonplanted ÎcontrolÌ wall. Retzlaff and the research team are implementing methodology and analysis protocols recently used for a similar G.R.E.E.N. research project that garnered a 2006 Environmental Protection Agency Phase I P3 Award.

Jost Greenhouses was the major supplier of all plant material for the research project; and, Ideal Landscape Group provided assistance and equipment to St. Louis Retaining Wall and SIUE for the installation of the test retaining wall systems.


Reviewing job performance, responding to customer feedback, and refining its fabrication process over the course of more than a decade and a half, Saint Louis Retaining Wall has produced the Hercules and Neptune product lines Û forerunners of the EcoWorks brand. Now, the EcoWorks line is touted as integral to furthering the evolution of green walls and, ultimately, constructed biosystems, i.e., engineered structures with living components.

Designed and fabricated with recycled fly and bottom ash, EcoWorks’ substantial green benefits derive as well from its constituents. Ash management specialist Charah processes the coal-combustion by-product on site at AmerenUE’s Labadie (Mo.) power plant, collecting, screening, blending and bagging the 100 percent post-industrial ash. Saint Louis Retaining Wall then purchases the ash for use in block production and module infill. Additionally, plant growth-promoting organic materials are mixed with the bottom ash to create a recycled ash blend media for testing as backfill on the SIUE project.

Concrete and cement production are among various construction and manufacturing applications for which Ameren recycles its ash, considered nonhazardous waste by the Environmental Protection Agency (EPA): blasting grit and structural fill; synthetic roofing shingles, lumber and bricks; and, snow and ice control through Ameren Energy Fuels and Services. With EcoWorks, landscape materials stand to incorporate bottom and fly ash for greater durability and more appealing aesthetics, while precasters consume by-products that would otherwise go unused. In 2006, over 500,000 tons of Labadie bottom ash were recycled in Missouri.

Saint Louis Retaining Wall anticipates that quantified test data from SIUE will advance sustainable retaining wall design, thereby abetting the national green movement and regulatory agencies. The company reports growing interest in the product line, as calls are received daily from architects, landscape designers, engineers and responsible developers expressing interest in the SIUE research. Also awaiting study data are Ameren and Charah, who expect that positive results will lead state regulators to more readily approve fly and bottom ash for use in public works projects like highway construction.
Û or 314/389-9255 for Saint Louis Retaining Wall Co.


During its 2007 Expo in San Francisco, the American Society of Landscape Architects (ASLA) announced development of a new rating system for sustainable landscape design. Taking a cue from the U.S. Green Building Council’s LEED rating system for a building’s environmental impact, the Sites Initiative will measure the sustainability of designed landscapes of all types, including public, commercial, and residential projects. The Council is lending its support to this project and plans to adopt Sustainable Sites metrics into LEED. This will provide the missing link for green building standards, said ASLA CEO Nancy Somerville. Developers, designers, owners and public officials will now have the tools at hand to significantly increase sustainability in the built environment.

In addition to ASLA and USGBC, program partners include the Environmental Protection Agency’s GreenScapes Program; National Recreation and Parks Association; American Society of Civil Engineers’ Environment and Water Resources Institute; National Association of County and City Health Officials; and, University of Texas Center for Sustainable Development.