15-0202 v2.1/Urban Agriculture and Freeway Proximity


The entire site of the project is within 500 yds. of a major urban expressway in an L5 transect area and is bounded by heavily traveled arterials. We are concerned with the accumulation of airborne pollutants in the garden soil specifically. We are exploring whether the proximity to the freeway to poses an immediate, yearly risk to crops intended for human consumption. Replacement of contaminated garden soil, on a regular schedule, perhaps every 5 years, is being considered but represents an ongoing maintenance expense for the owner.

Does the Institute have a standard for pollutant levels that would affect the urban agriculture component, either daily, yearly, or accumulative? If the project site exceeds acceptable levels of pollutants, is it acceptable for the project team to consider alternative agricultural strategies that would benefit the building residents, such as a market flower garden?


"The Living Building Challenge does not specify allowable contaminant levels for soils used for agricultural production; however, we appreciate your concern about the possibility of pollutants in crops due to proximity to a high traffic roadway. The US Environmental Protection Agency has published reports that indicate a causal relationship between a proximity to heavily trafficked roadways and a source of pollution for adjacent sites. Pollution can be transferred to the site in multiple ways, including via rain runoff, precipitation of substances onto the site, through the movement of groundwater and soil water and through wind. The potential impact, as well as the necessary mitigation, varies depending on the rate and transfer method. Each project team is responsible for determining appropriate urban agriculture solutions for a particular site, and should take into account exposure pathways for contamination (if present). Refer to the US EPA website, Growing Gardens in Urban Soils, for further information and resources, and consider adding a professional consultant to the project team if warranted. For Transect L5, there is a token amount of urban agriculture required - depending on the FAR, it correlates to 5%-10% of the total project boundary area (at a minimum). Please note that in-ground cultivation of produce is only one of numerous strategies that may be used to meet the requirements of the Urban Agriculture Imperative. Alternative options for produce include raised bed treatments and/or protective structures, such as a greenhouse. Project teams should keep in mind that the agricultural component of the project is not limited to the ground plane, but can also be located vertically, on rooftops, or in a combination of spaces. In addition, cultivation of produce such as vegetables is not the only means for achieving the Imperative’s requirements. Refer to a post in a related thread, “Definitions and Calculations” dated February 8, 2010, for other acceptable means. Though a market flower garden may provide other benefits, it does not meet the intent of this Imperative. Flowers grown for ornamental value do not establish ties between humans and our nourishment. "

Post ID 2128

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