Although spill incidents at loading and unloading facilities account for only 4% of the chemical accidents that occurred in Korea during the last four years, the increase is incremental each year. Loading and unloading facilities are equipped with trenches in preparation for mass drainage because transports by vehicle are frequent and physical blocking is difficult when a release accident occurs. Particularly, in the case of a chemical release with a high vapor pressure, the trench is effective to mitigate accidents by reducing the liquid surface to primarily prevent dispersion. This study proposes an improved trench system that can effectively and rapidly withdraw large amounts of chemicals spilled from transport vehicles. Assuming a total volume leakage of a 55% hydrofluoric acid (HFA) solution from a transport vehicle, the study confirmed the risk-reducing effect by comparing using the consequence analysis program (ALOHA) and Probit analysis. The results show that minimizing the time that the released chemicals stay in the trench using control system (pH meter and automatic valve) can reduce the amount of chemicals vaporizing, thereby minimizing the effect distance of the release incident.