To prevent pest infestation of an outdoor dumpster, ensure that the dumpster has a tight-fitting lid and that it remains closed when not in use. Line the dumpster with heavy-duty bags to prevent leakage and odors, and schedule regular cleanings to remove food residue and waste buildup. Place the dumpster away from the building and ensure the area around it is free of debris or standing water. Regular inspections and pest monitoring can help identify and address any issues promptly.