Stormwater Utility Fee Estimation Method for Individual Land Use Areas

In South Korea, a reasonable rate system that can be domestically applied to calculate sewage and stormwater separately from the domestic sewage fee system is needed. This study proposed a phased pricing scenario to separate sewage and stormwater in Bupyeong-gu, Incheon, and the rate changes were compared based on a simulated calculation of the stormwater utility fee. In this investigation, stormwater runoff cases from other countries and the current domestic system were analyzed. A stormwater utility fee introduction scenario was presented that considers the impervious surface area. Water and sewage usage statistics and hydrant spatial data were collected from the Incheon Metropolitan City Waterworks Authority, and the total amount of water and sewage fees from the land use area were calculated. The stormwater utility fee was calculated, and the rates of each step were compared. The total sewage fee of Bupyeong-gu during 2014 was KRW 21,685,446,578, and the phased stormwater utility fee was calculated, assuming that 40% represents the stormwater cost. The sewage fee for the residential area in phase 3 decreased by 0.77% compared to phase 1. For the commercial areas, the sewage fee decreased by 36.87%. Because the impervious surface ratio was high, the overall area contributing to the impervious surface area was small. In the industrial area, the sewage fee increased by 8.35%. In the green area, the sewage fee increased by 37.46%. The sewage fee for the apartment complexes decreased by 10.6%. Finally, the possibility of estimating the actual stormwater utility fee was confirmed.