Phillip Cesena transferred to San Franciscquito Canyon in February 1928 to work as a ranch hand, mucking out stalls and exercising ranch animals. The 15-year-old had just lost his father, Leonardo, and wanted to support his mother, Erolinda, and his 12 brothers and sisters by learning how to break horses and perform trick riding for Hollywood westerns. A month later, Cesena’s fate was sealed. The St. Francis Dam burst, sending 12.6 billion gallons of water 15 stories high racing through Santa Clarita, Saugus, Saticoy, Piru, Fillmore and Santa Paula. The water wiped out villages and killed about 450 people before reaching the ocean near Oxnard some 54 miles away. … Now, one community organizer is leading a push to build a memorial to remember Cesena and all the others who perished in what some call the worst civil engineering disaster in the country’s history.