Application of Groundwater Modeling Tools to Evaluate Potential Impacts from Stormwater Infiltration in Philadelphia

摘要

The Philadelphia Water Department?s (PWD) Green City, Clean Waters program involves awidespread application of green stormwater infrastructure (GSI) across its combined seweroverflow area. The program is part of the proposed long term control plan update for combinedsewer overflow control in which GSI will be applied to more than 40% of the impervious coverover the next 25 years. A major concern regarding infiltration-type GSI is excessive groundwatertable mounding such that it infiltrates into neighboring basements. PWD has evaluatedgroundwater mounding using three-dimensional groundwater models and is applying the modelsto site-specific designs to help refine a set of design criteria for GSI projects. Transientgroundwater modeling to date shows that the water table could mound more than 1.37 meters(4.5 feet) immediately beneath infiltration trenches following significant rain events, however,the mounding is much less a short distance away from the infiltration trench and dissipates overseveral days.