Transportation facilities such as parking lots and maintenance yards often do not have provisions to treat storm water before discharge. Catch basin inserts can provide a retrofit alternative as a method to meet the new National Pollution Discharge Elimination System Phase II storm water pollution prevention regulations. Inserts produced by four manufacturers were evaluated for removal of suspended solids and petroleum hydrocarbons by using a pilot scale catch basin and synthetic storm water. In addition, the inserts were placed at operating transportation facilities and monitored for operational problems. At a flow rate of approximately 0.013 cu m/s (200 gal/min) and pollutant concentrations for total suspended solids (TSS) and total petroleum hydrocarbons (TPH) of 225 mg/L and 31 mg/L, respectively, the inserts were capable of removing 11% to 42% of TSS and 10% to 19% of TPH.