MODELING LOW IMPACT DEVELOPMENT HYDROLOGY: CASE STUDIES USING THE LIFE™ MODEL

This paper presents applications of the Low Impact Feasibility Evaluation (LIFE™) model, a model developed by CH2M HILL from basic hydrologic principles to simulate Low Impact Development (LID) hydrology. The LIFE™ model is a continuous-simulation model, based primarily on physical processes that occur with bioretention facilities, vegetated swales, green roofs, and infiltration devices, as well as the effects of site fingerprinting and soil compaction. The LIFE™ model accounts for runoff generation from all categories of land cover including roadways, landscaping, and buildings over a variety of land uses and soil types, for new development and re-development. The model allows for precise definition of planning and engineering measures implemented to control stormwater; for example disturbance avoidance, soil amendment, pavement replacement, and street narrowing. In addition, the model includes an evolutionary optimizer for maximization of project benefits.The LIFE™ model has been applied in a number of projects in the US and Canada. This paper describes four applications in Washington State, Virginia, North Carolina, and British Columbia. The applications cover a range of geographical locations, soil types, land uses, and stormwater management objectives, including stream protection, water quality improvement, combined sewer overflow (CSO) reduction, rainwater reuse, and sustainable land development.