| Description |
Low impact development (LID) is gaining popularity for its ability to revert developed landscapes to their historical hydrology and thus enhance sustainability. Utilizing a case study of a low impact development in the Salt Lake City Valley in Utah, a comparison of the effects of centralized infiltration to different LID technologies was conducted. Stormwater simulated rainfall-runoff models were created using the U.S. Environmental Protection Agency's Storm Water Management Model (SWMM). To evaluate several scenarios models with different features were developed: no controls (developed land with no stormwater control); centralized infiltration (large infiltration basins); rainwater harvesting (rain barrels); porous pavement; bioretention; and a comprehensive model with all of the LID features together. The results of the models show statistically significant (p<0.05 and t stat>t critical) decreases in average annual total flow volume, average annual mean flows, and average annual peak flows from the no controls model. For all reductions, a comparison of model performance in wet and dry years (a classification based on precipitation amounts) was completed. This revealed that the centralized infiltration model performs better in dry years, the comprehensive LID, porous pavement, and bioretention models perform better in wet years, and finally that rainwater harvesting generates similar reductions in outflow regardless of the type of year. A cost analysis of the models was conducted in order to help quantify the use of the technologies. In terms of costs per volume reductions, bioretention proved to be the least expensive option, followed by rainwater harvesting, centralized infiltration basins, comprehensive LID, and finally porous pavement. Based on these results, the final recommendation is that projects should first consider bioretention and then rainwater harvesting as options for stormwater management. Porous pavement is an effective choice, however, its cost is a deterrent. Comprehensive LID model provides successful reductions but at a higher cost due to the inclusion of porous pavement. Centralized infiltration is still a good choice for new developments since it is shown to be very effective, however the land amount it requires for implementation may be a deterrent for using this type of stormwater management in retrofitting projects. |
