Green Stormwater Infrastructure
Prior to the 1970's, many US cities managed stormwater through piped conveyance systems. Flooding was once considered the most significant risk associated with rainfall. System builders built water infrastructure to accommodate volume. Most cities in the US have what is called a combined sewer system (CSS). This system pipes stormwater and municipal wastewater together. The water is then treated and then released into receiving bodies. St. Louis is one of the rare cities (Baltimore, where my research is based is another) that has a municipal separated stormwater system (MS4). In a separated system, a system of pipes keeps stormwater separate from other wastewaters.
In the 1970's ecological research, some of which came from the EPA's National Urban Research Program, began to demonstrate that nutrients in runoff were responsible for environmental pollution. In turn, municipal engineers transitioned to thinking about tools and techniques for decreasing this nutrient load. In St. Louis, the separated system operates under a federal consent decree with the EPA where the city must reduce the overall percentage of nutrients (nitrogen and phosphorus) carried through runoff. The most recent strategy for managing this problem is Green Stormwater Infrastructure (GSI). Although the problems associated with GSI are of local relevance, they are managed through state and federal governance strategies.
While GSI is difficult to define, many times installations feature landscaped elements that aim to mimic the pre-development hydrological processes of a given site. In urban areas, these projects often utilize vacant lands or reduce existing impervious surface cover. Many planners and community groups also suggest that GSI provides additional social benefits through an increase in community green space, reduction in urban heat island, and improved property values.
This image from Missouri Coalition for the environment brings together the many suggested benefits of implementing these technologies. The diagram also provokes some questions that may interest us in our project; Does GSI represent a paradigmatic shift in techniques of stormwater management? Does natural or environmental mimicry in engineering projects act as a corrective to the anthropocene, or are these technologies merely a response? How are the social, economic, and technical benefits of GSI calculated and have attendent burdens been considered as well?