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The Downers Grove Sanitary District (DGSD) operates a wastewater treatment facility providing service to residential, commercial, industrial, and institutional customers. Donohue provided engineering assistance to the DGSD to analyze alternatives for utilizing a portion of a building that houses outdated and unused filtration equipment referred to as microstrainers.
As part of this study, Donohue evaluated the loading capacity for a proposed "green roof". Three types of green roof assemblies were available, each with different capacity requirements. Basic designs, called Extensive assemblies, require little maintenance and induce little extra load on roof supports; Intensive assemblies, on the other hand, require irrigation and maintenance and introduce a substantial load on the roof. The third option, Shallow-Intensive, fell in the middle in terms of maintenance and load requirements. A structural assessment was performed and determined that the Extensive assembly was the best candidate for the Microstrainer Building and DGSD's purposes. The roof has not yet been built.
Green roofs, such as the ones pictured above, provide a host of benefits for both the environment and owners. For our clients, green roof assemblies protect the roof membrane, prolonging the life of the roof. They also reduce stormwater runoff and delay drainage during peak flows, reducing pressure on wastewater treatment plants and the sewer system.
Green roofs also improve the thermal properties of the structure, providing an insulating effect that keeps the building cooler in summer and warmer in winter. In addition to indoor climate control, in large, urban areas, green roofs tend to mitigate the "urban heat island" effect, which is cause by considerable amounts of heat-absorbing materials such as concrete and asphalt. |
