American Society of Civil Engineers

In Situ Bioretention Design Concept

by Michael Clar, (Department of Land Use, New Castle County, DE 19720 E-mail:
Section: Advances in LID BMP Design Methods—Lessons Learned, pp. 96-103, (doi:

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Document type: Conference Proceeding Paper
Part of: Low Impact Development 2010: Redefining Water in the City
Abstract: Since its initial development and application in 1993, the bioretention system also referred to as "rain gardens" has rapidly become one of the most versatile and widely used BMPs throughout the US and many parts of the world. It has recently become identified as a preferred site practice for green building design and LEEDS certification. The current practice in bioretention design largely follows the initial guidance developed by the author in 1993 and consists of excavating existing soils and replacing with either or natural or artificial "soil media". While this approach may still be necessary in some instances, there are many situations where the existing soils may not need to be totally removed but instead can be augmented in-situ to provide a more sustainable and low cost approach to bioretention design. This paper describes the procedure which is being developed in New Castle County, DE to facilitate the use of in-situ bioretention design. The design procedure is described and the benefits of this design approach are identified.

ASCE Subject Headings:
Biological processes
Water treatment