Improvement of Non-point Source Pollution Reduction Performance Evaluation Method for Infiltration Trenches

The Low Impact Development (LID) method is drawing attention as a way to minimize negative changes in the hydrologic and water quality environment, such as the increase of stormwater (runoff) and non-point pollutants discharge by rapid urbanization. In Korea, LID facilities are classified as a type of Non-point Pollution Reduction (NPR) facilities and their performance has been evaluated using the simple formula presented as a central government guideline. However, since LID facilities are installed on a relatively small scale and are composed of materials such as gravel and soils unlike NPR facilities, which are normally installed on a large scale and have empty detention volume, it is expected that there will be limitations in evaluating two facilities with different characteristics in the same way. Therefore, this presentation presents a new performance evaluation method suitable for LID facilities to minimize errors in performance evaluation of LID facilities (especially focusing on infiltration trenches). Fist of all, SWMM was used to reproduce the behavior of stormwater and TP in our study area which represents the hydrologic and water quality phenomena of a typical Korean urban area, and SWMM-LID module was used to simulate stormwater and TP interception performance by installing a infiltration trench, one of the major LID facilities, under various conditions through long-term simulations. Finally, from the simulation results, the Stormwater Interception Ratio (SIR) and Load Capture Ratio (LCR) empirical formulas based on the ratio of facility area and contributing area were derived in the same form as the existing formulas provided by the guideline. As a result of estimating the performance of the infiltration trench using the existing formula and the formula derived from this study, it is very likely that the existing formula overestimates the stormwater interception performance of the infiltration trench and underestimates the load capture performance of the facility. Finally, limitations of this study will be presented.

Acknowledgment

This work was supported by Korea Environment Industry & Technology Institute(KEITI) through Public Technology Program based on Environmental Policy Project, funded by Korea Ministry of Environment(MOE)(2016000200002).