Stormwater Quality from Gas Stations in Tijuana, Mexico

There are many potential sources of stormwater pollutants in urban areas; one of these sources is gas stations, which are numerous and spread city-wide. A study was conducted to evaluate the water quality of runoff from gas stations in the city of Tijuana, Mexico. Pollutant loads in runoff from gas stations in the study area were higher than in other published studies. The estimated loads from gas stations of oil and grease (OG), total suspended solids (TSS) and chemical oxygen demand (COD) were 39.9, 265.3 and 168.6 Kg/ha, respectively. These values of OG, TSS and COD were 57, 41 and 18 times higher than the values reported in another similar study conducted in the US. The possible reasons for these differences may lie in the different cleaning processes utilized in gas stations, in the mechanical conditions of the cars that enter the sites and the urban characteristics surrounding the gas stations. The results from this study show that runoff from gas stations can be a main contributor of pollutants such as suspended solids, heavy metals, oil and grease to stormwater and water bodies.